Strand7 Webnotes - ST7-1.50 Modelling

ST7-1.50 Modelling
ST7-1.50.10 Modelling / Automeshing
1.1 MB	ST7-1.50.10.1 Surface Automeshing Geometry and Hex Extrusion It is often optimal to use a combination of automeshing and manual meshing. This Webnote covers an example of a reinforced end detail of a steel pile, which is first automeshed then extruded into a solid hexahedral mesh. The given geometry consists of 6 faces. These faces partially overlap, which will have to be corrected before automeshing can be successful. The 3D mesh to be built is shown below. Open ST7-1.50.10.1 Cruciform.st7. Use Tools/Geometry Tools/Graft Edges to Faces. ...
1.4 MB	ST7-1.50.10.2 Surface Automeshing an Excavator Assembly The Strand7 automeshing module enables you to rapidly mesh imported CAD geometry. The geometry tools in Strand7 allow you to split and heal geometry to prepare it for automeshing when the initial imported geometry is lacking enough definition for FEA purposes. The geometry for this example is shown at right. The Webnote covers: Importing and cleaning CAD geometry Application of attributes to geometry Default automeshing Automesh quality assurance and common pitfalls The focus...
1.8 MB	ST7-1.50.10.5 Reducing Solid Geometry to Surfaces for Plate Meshing The document demonstrates geometry manipulation techniques within Strand7 which can be used to produce geometry suitable for plate meshing from solid CAD geometry. A model of a tank is used to demonstrate this reduction in geometric complexity. The solid geometry of the tank is shown below. Solid geometry essentially has more than double the number of faces needed to produce a surface mesh. In this example, the inner surface of the tank touches much less than the outer surface, so we will...
4.9 MB	ST7-1.50.10.6 Solid Automeshing Multiple Connected Bodies It is common when solid automeshing to have geometry which shares an interface with another part to which it is integrally connected. The model geometry is shown at right. It consists of an irregular stack of blocks, which could be bonded or just in contact. The overall modelling procedure will be to import the geometry, clean it up and mesh it such that there is a common node pattern at the interface between each body (compatible meshes). If each of the blocks is a fully enclosed solid which...
1.3 MB	ST7-1.50.10.7 Generating Geometry in Strand7 Strand7 offers a range of tools to help create and manipulate geometry in preparation for automeshing. These tools are not intended as an alternative to a CAD package, however, they offer sufficient functionality to generate various basic geometries from scratch, and more importantly, to make minor additions and modifications to imported CAD geometry - this can often avoid the need to go back to the CAD package to correct unmeshable geometry.
0.9 MB	ST7-1.50.10.9 Geometry Creation of a Cast-in Bearing Plate Bracket Often engineers must design custom components when detailing structural connections or member supports. As this bracket is fairly small in size and geometrically simple, manual meshing is certainly a feasible option, however given the speed at which three dimensional models can be produced in any number of available CAD packages, and the simplified modelling allowed by the Automeshing tool in Strand7, the latter approach will be outlined here. In order to simplify the model, rather than modelling...
0.9 MB	ST7-1.50.10.16 Overview of Geometry Tools Creating meshes to simulate complex geometry can be very time consuming. The geometry importer, geometry tools and automeshing tools make it possible to convert CAD created geometry into an FEA model. This Webnote focuses on the geometry tools and how they can be used to process the geometry imported from a CAD package to be suitable for automeshing. Some content of this Webnote is also covered in the Strand7 Online Help and Strand7 Tutorials, which can be consulted for extended description...
5.7 MB	ST7-1.50.10.20 Checking and Correcting Brick Faces Assessing the quality of a surface representation of a brick mesh can be achieved by creating plate elements on the surface. These plates can then be measured and inspected. They can also be left in the analysis if their properties are set such that they do not influence the solution (e.g. by setting their modulus or thickness to a very small value). The example model is from ST7-1.40.70.15 Engine Head Gasket Analysis, in which it is analysed using the nonlinear static solver for the contact...
ST7-1.50.20 Modelling / Manual Meshing
0.9 MB	ST7-1.50.20.1 Meshing a Conical Surface by Projection This Webnote shows how to create a high quality mesh on a conical surface by projecting a mesh from a flat surface. This procedure assumes that you have a high quality mesh on a quarter of a circular plate, as shown at right. The mesh can be found in ST7-1.50.20.1 Cone_Base.st7. Create a cylindrical coordinate system with the origin at the corner of the quarter circle model and the cylindrical Z axis parallel to the global Z axis. Create a node which represents the apex of the cone,...
0.6 MB	ST7-1.50.20.2 Meshing a Plate with a Hole This document steps through the procedure required to create the mesh for a plate with a hole in it. One method for refining the mesh around the hole will be discussed. The example will build a plate 600 mm long by 400 mm wide. A hole 100mm in diameter is located directly at the centre. Due to the symmetry of the plate, only one quarter of the full model needs to be created. The full mesh can be created later by mirroring the quarter model. Select File/New from the main menu and set the...
0.7 MB	ST7-1.50.20.3 Meshing a Solid Cylinder This Webnote provides an example of manual mesh generation. Strand7 meshing tools are used to create the mesh for a solid cylinder, show on the right. Only a quarter of the cylinder is modelled due to symmetry. Create a new file with length units of Nmm. Right-click the Show/Hide Snap Grid button and enter the parameters shown. Enter the Create tab, select Quad4 and click OK. Hide the snap grid. Select Tools/Grade Plates and Bricks from the main menu. Using the grade option...
0.7 MB	ST7-1.50.20.4 Meshing a Pipe Elbow and Flange This document outlines the procedure for creating a 90 pipe elbow using plate elements. This procedure could be adapted to model an elbow of any angle. It could also be adapted for use with beam or brick elements. The pipe geometry is shown on the right. A straight section of pipe mesh is provided and a 90 elbow is to be modelled. The flange is a 10 mm annulus on the end of the elbow. The initial straight section of the pipe has been provided in the file ST7-1.50.20.4 StraightPipe.st7. ...
0.6 MB	ST7-1.50.20.5 Intersecting Cylinders This Webnote presents a method for creating a plate mesh representing two intersecting cylindrical surfaces using advanced manual meshing tools available in Strand7. Irrespective of whether the two cylinders are of the same or different diameters, the complex geometry at the intersection requires some planning to avoid poorly shaped elements. The best approach is to initially generate as coarse a mesh as possible and to refine it after the geometry has been correctly adjusted. Fillets...
1.1 MB	ST7-1.50.20.6 Extrusion Meshing in Multiple Directions Some solid parts can be made of multiple intersecting extruded parts. In these cases it may be desirable to create an extruded Hexa8 or Hexa20 mesh instead of an unordered Tet10 mesh, because the number of nodes for a given accuracy may be greatly reduced. The geometry shown below can be extrusion meshed. It could be modelled using two extrusion directions, one for the stub and one for the supporting base. Firstly, it is important to plan out the extrusion sequence. Hold shift and hover over...
0.8 MB	ST7-1.50.20.7 Creating Cylindrical Features in an Existing Mesh This document describes a general method for creating features that have circular or cylindrical shape. Typically this can be achieved by performing mesh manipulation with reference to a Cylindrical UCS defined at a convenient location. Some mesh adjustment may be required after a feature is added to the mesh to ensure mesh compatibility. In this example a 100 mm diameter pipe, representing a nozzle, is added to the top of a tank. The creation of circular or cylindrically shaped features is...
0.5 MB	ST7-1.50.20.8 Forming Compatible Mesh via Extrusion to Surface In many real life structures, the connection detail between two components is not orthogonal, and may occur on a non-flat plane. This introduces some complexity into the modelling approach required to produce a compatible mesh. It is possible to produce a compatible mesh by using a variety of Strand7 tools. We will be examining an example of a connection between two pipes that meets at an angle. To simplify the mesh manipulation, the plate elements representing the main pipe and side pipe are...
0.4 MB	ST7-1.50.20.9 Modelling a Helix or Spiral Modelling a helix or spiral in Strand7 can be done using Tools/Extrude/By Increment with a cylindrical UCS. First, create a cylindrical UCS at the centreline of the helix. Create a new UCS using Global/Coordinate Systems. Choose Cylindrical under System. Choose ZX under Type, or choose the plane which appropriately aligns the Z axis with the axis of the helix. If you have a node at the centreline, activate the Origin node hotpointer and select the centreline node. Click Apply. Create...
1.1 MB	ST7-1.50.20.10 Advanced Grading Techniques This Webnote examines manual mesh refinement techniques using the Grade Plates and Bricks tool. An important part of building a finite element model is mesh refinement around areas of stress concentration, changes in geometry, or in other areas of interest. The Grade Plates and Bricks tool can be used to define the transition from a coarse mesh to a fine mesh, whilst ensuring that all elements are fully connected and retain acceptable aspect ratios. Strand7 offers many options to mesh these transitions, for example, to go from four elements to two or from three elements to one.
2.1 MB	ST7-1.50.20.11 Creating Interface Elements between Coincident Geometry This Webnote illustrates operations and tools for creating interfaces between component parts, such as is required for the analysis of contacting bodies, or simply for disconnecting parts that have been zipped together. Although the physical parts may actually be coincident and may have been modelled in that way in a CAD program, for FEA purposes it is often necessary to introduce a small physical gap between the parts so that contact or other interface elements may be inserted.
1.3 MB	ST7-1.50.20.12 Interfacing Different Element Types This Webnote examines the modelling considerations required to connect different element types - beams, plates, and bricks. In a mesh connecting different element types, simple element-to-element connection at the node may not transfer all load components correctly. Additional interface entities can be introduced to ensure compatibility of all degrees of freedom at the interface.
0.4 MB	ST7-1.50.20.14 Using the Points and Lines Tool to Build Models This Webnote examines the node and beam element creation tools available in the Points and Lines tool. The dialog corresponding to this tool includes a range of options for creating nodes and beam elements in geometric configurations such as parabolas, circular arcs, as well as features like fillets and tangent lines. The tool also offers options to create construction features based on existing entities, such as finding the centre of a circular arc, and extending existing lines.
1.1 MB	ST7-1.50.20.16 Advanced Extrusion Meshing This Webnote examines the Strand7 advanced extrusion options. Strand7 has the following extrusion options. by Increment; by Direction; by Projection; by Thickness; by Line; and to Absolute. The Extrude by Increment and Extrude to Absolute options are the most commonly-used options in manual meshing. This Webnote presents some applications of all the extrusion options and gives the user some modelling tips about using these options in modelling.
1.6 MB	ST7-1.50.20.18 Modelling Intersecting Pipes with Hexahedral Elements This Webnote illustrates techniques to manually create a mesh of intersecting pipes using 20-noded hexahedral elements. Tools such as extrude by projection, fillet plates and subdivide are used to produce the final mesh. Create two beam elements connected at right-angles. This represents a cut on the XY-plane where the outer surface of the branch pipe (vertical beam) meets the outer surface of the main pipe (horizontal beam), before the fillet is applied. Create a Cylindrical UCS aligned...
ST7-1.50.30 Modelling / Loading
0.5 MB	ST7-1.50.30.1 Wind Loads on Shell Elements Wind loads are often expressed in terms of force per unit length, and often vary with respect to height. It is quite easy to apply this sort of loading to a beam element using a distributed force, but applying equivalent wind loading to a shell element mesh takes some additional consideration. This document outlines how to apply an equivalent varying wind load to both beam and shell elements. A 1.5 m diameter tower is considered. Given a wind load of 30 kgf/m at a height of 4 m, and 100 kgf/m...
0.8 MB	ST7-1.50.30.2 Applying Moments to a Brick Mesh 3D solid elements (otherwise referred to as brick elements) do not contain rotational degrees of freedom in the element formulations. Each node in a brick element has only three translational degrees of freedom, meaning that the displacements DX, DY and DZ are calculated, while the rotations RX, RY and RZ (and corresponding moments) are not considered. If one were to apply a point moment directly to a brick mesh, it would be ignored as reflected in the solver log file Warning 6.
5.2 MB	ST7-1.50.30.3 Load Patches for Area Load Area Load (or Floor Load), as referred to by some other engineering software packages, is equivalent to Load Patches in Strand7. In this Webnote we look at how load patches can be applied to model these situations. However, since the patch plates in Strand7 are very flexible, they can also be applied to non-planar meshes in 3D space; some examples are illustrated in this Webnote. The following structure is provided: A floor live load of 30 kPa is to be applied to the structure. Open the...
1.6 MB	ST7-1.50.30.4 Using the Moving Load Module This Webnote outlines the use of the Strand7 Moving Load module for the modelling of transient loads moving along a path, the generation of load cases relevant to the possible positions of loads moving along a path, and to create static combination of loads moving along a path that minimises or maximises a specified response variable. Whilst each of these capabilities addresses different analysis types, central to them all is the definition of moving loads in a Load Path Template. In Strand7,...
0.7 MB	ST7-1.50.30.6 Using Normal Pressure to Fold a Box The plate normal pressure attribute updates the direction of applied load as the structure deforms in a geometric nonlinear analysis. This means it can be used to apply load which causes structure to fold or wrap around other structure. In this Webnote we examine the folding of a box from a flat creased aluminium plate. The load is then released and the spring-back effect is measured. The starting planform shape of the box is shown at right. The model needs to have contact elements defined...
0.5 MB	ST7-1.50.30.8 Global Pressure Attribute Projection Options This Webnote examines the load projection options for Global Distributed Force and Face Pressure attributes. The projection options dictate whether the total surface area or only the projected area of the element is used to calculate the total applied load. For area projection two methods are considered, namely projection in the direction of each load component, and projection in the direction of the load resultant.
9.3 MB	ST7-1.50.30.14 Balancing Load in Pressure Vessels with Openings When modelling contained pressure loads that act on the structure, it is important that the load be balanced to model the physical reality accurately. That is, if there is an opening in the pressurised body, the lack of applied pressure on the opening (due to lack of finite elements that cover up these openings) will result in a large force imbalance. This effect is analogous to that of a propelling nozzle.
ST7-1.50.40 Modelling / Contact
0.6 MB	ST7-1.50.40.1 Multi-Body Contact of a Rubber Bushing Assembly There are several ways to connect multiple bodies to form contact surfaces. We will cover the case where the bodies are completely separate and have meshes which do not necessarily line up across the gaps between them. A rubber bushing used to restrain a window pane is analysed. It consists of 5 parts, one of which is a co-moulded steel-rubber bushing. The analysis we will perform on the bushing assembly is Axisymmetric. Create a new file. Set the units to Nmm. Import the file Bushing...
2.4 MB	ST7-1.50.40.2 3D Solid Multi-Body Contact A sliding joint model is built by extrusion and automeshing methods. Contact is defined between the two bodies to determine the response of the multi-body system. Open ST7-1.50.40.2 Sliding Joint.st7. Note that there are two groups defined (Global/Groups). Turn off the group Stub and Base. Select the face which defines the cross-section of the track. Automesh the face with an edge length of about 2.4 mm using Tools/Automeshing/Surface Mesh. Extrude this mesh to 120 mm length in...
1.0 MB	ST7-1.50.40.4 Defining Contact Interfaces Contact between multiple bodies in Strand7 is achieved using contact elements, which are a type of beam element. Whenever possible, it is best to use node to node contact, which is simply a contact beam element connecting two nodes. This is generally done in situations where there is a regular mesh, or the mesh on either side of the gap is the same, facilitating extrusion of contact beam elements between them. In the model shown at right, contact has been defined between the nodes on the two...
0.5 MB	ST7-1.50.40.5 Determining Appropriate Contact Stiffness Contact is modelled in Strand7 using a special type of beam element. These beam elements react load nonlinearly, and in proportion to axial compression. The stiffness of these contact elements can affect the solution results accuracy and convergence. There are many physical situations that may be modelled with various configurations of contact elements. This Webnote aims to provide a guideline of what the axial stiffness value should be. Refer to ST7-1.57.20.8 Contact Element Fundamental...
1.2 MB	ST7-1.50.40.8 Sliding Contact This Webnote introduces a technique that can be used to model sliding contact with pre-strained cutoff bar elements. Examples including pedestrian step loading, sliding of an interference fit, and reeling of a cable onto a spool are presented. We will use the following example to introduce the idea: A person of mass of 70 kg walks across a simply-supported steel beam 8 m long with 1000x100x10 mm rectangular hollow section. Create a new model and choose Nmm as the unit system. Create...
ST7-1.50.50 Modelling / Details
1.9 MB	ST7-1.50.50.1 Bolted Joints Bolted joints can be modelled using Strand7 with varying levels of detail depending on the level of accuracy and local detail required in the analysis. Five options are presented, each with increasing levels of complexity.
0.6 MB	ST7-1.50.50.2 Beam End Releases Beam end releases are provided as a beam element attribute in Strand7. These attributes can be applied to one or both ends of a beam element. Both translations and rotations can be independently released to model a variety of joint configurations. Where no end release is applied, two beam elements that share a node are modelled as being welded together. Using end release attributes, ends of beam elements can be fixed (no end release), partially released (where a connection stiffness is specified),...
0.6 MB	ST7-1.50.50.3 Tapered Beams It is common to use beams which are tapered in engineering structures. One approach for modelling a continuous tapered beam is to use a sequence of untapered beam elements of varying size as shown below. This modelling approach could take considerable time for models with many tapered beams, as the accuracy of the solution may require many stepped beams. However, to reduce modelling time and solution time, and to improve accuracy, the beam Taper attribute may be applied to beam elements....
0.9 MB	ST7-1.50.50.4 Modelling with Cables This Webnote examines different modelling approaches for cables and slender members with only axial capacity. The modelling consideration of tension-only capacity is also examined. Such cables and slender members can be modelled using Cable, Truss and Cutoff Bar type Beam elements in Strand7.
0.7 MB	ST7-1.50.50.6 Using String Groups The Beam String Group attribute is used to model a continuous chain of truss type beam elements sliding through frictionless connections at nodes. The attribute ensures that a constant axial force develops in all the elements in the same string group. A common application of the attribute is to model massless cables (or strings) such as pulley systems, lifting sling cables, and pre-stressed steel tendons in reinforced concrete. This Webnote examines the Beam String Group attribute and its modelling applications.
1.5 MB	ST7-1.50.50.8 Simplified Spline Contact and Fatigue Analysis In this Webnote we model the end of a winch drum which has a 60 mm diameter spline with 50 teeth. The effect of the spline is all that is needed the local stress in the teeth of the spline are not of interest. Fatigue analysis of the hub is the primary concern. Thus, we can use a simplified approach which gives an accurate coupling of the input shaft and winch, while maintaining a reasonably small model size. The interface between the male and female parts of a spline is complex. The gap...
0.7 MB	ST7-1.50.50.18 Beam Element Orientation This Webnote discusses how beam elements are orientated in Strand7, together with methods for changing the orientation. The orientation of both Beam2 and Beam3 elements is presented. By default, Strand7 beam elements are aligned according to the principal axes of the cross section. Principal axes for an I-section, as shown in the Geometry tab of the Beam Property dialog, are illustrated at right. The orientation of the Beam2 element is fully specified by the definition of two non-coincident...
ST7-1.50.60 Modelling / Links
0.4 MB	ST7-1.50.60.1 Link Types The various link types available in Strand7 are summarized below, including example uses. ...
0.5 MB	ST7-1.50.60.2 Link Forces Links do not produce output like other FEA entity types (e.g. plate elements). We must instead extract the forces from links using one of two techniques, which are outlined below. The first involves Element Node Force, which is used to create free body diagrams at the link interface. The second makes use of Node Reaction output, which holds the forces due to restraints and can be modified to extract link forces as well. Consider the plane stress model below, which is included as ST7-1.50.60.2...
1.5 MB	ST7-1.50.60.3 Using Attachment Links Although it is generally preferable to have full mesh compatibility between connected parts, in practice this is sometimes very difficult, if not impossible. Attachment attributes offer a versatile way of joining dissimilar meshes so that displacement compatibility is enforced by multi-point constraint equations that are automatically generated.
0.6 MB	ST7-1.50.60.5 Using Master-Slave Links Master-Slave links are often misused, which can lead to non-physical behaviour. This Webnote outlines typical valid uses of the Master-Slave link, illustrates how the Master-Slave link differs from the Rigid Link, and summarises some of the common pitfalls of using Master-Slave links.
0.4 MB	ST7-1.50.60.7 Master-Slave Link Considerations Master-Slave links provide a method of directly relating the degrees of freedom of two nodes in the mesh. These link types are normally intended to connect small gaps. Since the length of the link is not considered, usage over large gaps can lead to some non-intuitive results. This Webnote outlines the behaviour of Master-Slave links in some specific situations. From the point of view of moment calculations Master-Slave links are effectively of zero length. Consider the top mechanism shown...
1.0 MB	ST7-1.50.60.8 Using Links to Model Rigid Diaphragms Certain structural members can be modelled as having infinite in-plane stiffness, and zero out-of-plane stiffness. This is typically done in the analysis of buildings, in which the floors are assumed to act in this way during seismic events. To achieve this, Strand7 provides a special type of planar rigid link cluster, in which the plane with infinite stiffness is specified by the user. A simple example is developed in which the floors of the six storey building from ST7-1.40.35.22 AS 1170.4-2007...
ST7-1.50.70 Modelling / Attributes
0.4 MB	ST7-1.50.70.1 Beam End Release and Node Displacement in GNL Analysis This Webnote describes the relationship between the beam end release results and nodal displacement for linear and geometric nonlinear (GNL) solution cases. The focus here is on the rotational end release attribute, but the discussion is also applicable to the translational end release attribute. The default joint condition for a beam element in Strand7 is that of a welded joint. Strand7 has two Beam End Release attributes: one is the translational end release and the other is the rotational...
0.6 MB	ST7-1.50.70.2 Beam Bending and Nodal Rotational Stiffness This Webnote illustrates the changing bending moment at the ends of beams subjected to uniformly distributed loads due to the effect of nodal restraints and joint connections. Consider a beam subjected to a uniformly distributed load as shown in the illustration. If the ends of the beam are pinned (nodes assigned zero rotational stiffness) then the bending moment at these ends is zero. If the ends of the beam are fully fixed (nodes assigned infinite rotational stiffness) then the bending...
0.7 MB	ST7-1.50.70.3 Modelling Soil with Support Attributes When modelling a structure which is supported by soil, it is often simpler to model the soil with a support attribute. These attributes model the linear elastic response of a supporting medium. This Webnote outlines the basic procedure to apply supports equivalent to that of the surrounding grade. Support attributes only represent normal support; shear stiffness is not possible using support attributes alone. Support attributes can be applied to all element types. When applying brick face...
0.5 MB	ST7-1.50.70.5 Contouring Nodal Attributes Strand7 allows the automatic contouring of element attributes, but not nodal attributes. However, there is a way to contour nodal attribute values on elements by using the Online Editor, Excel and a user defined nodal contour file. A complex nodal loading is applied to the nodes of some plate elements shown at right for the purpose of demonstrating nodal attribute contours. This method applies to any other nodal attribute, and also to brick or beam elements. The following general procedure...
1.0 MB	ST7-1.50.70.9 Assigning Attributes to Geometry After importing CAD geometry, attributes can be applied directly to the geometry. These attributes are then automatically inherited by finite elements after automeshing. Advantages of applying attributes to geometry include: Work is factored out when successive models are required (for example, as a part of a mesh refinement sensitivity study); and The geometry stage typically has far fewer entities and can therefore be easier to work with.
1.1 MB	ST7-1.50.70.10 Assigning Attributes using Equations Strand7 attributes can be applied using an equation which references the currently active coordinate system directions. Any UCS type (cartesian, cylindrical, toroidal or spherical) can be used. This functionality can be used to define non-uniform attributes on nodes and elements. Attributes which are applied with an equation only reference the equation at time of application. If the UCS is changed or the entity is moved the attributes will remain unchanged. Create a cylindrical UCS centred...
0.7 MB	ST7-1.50.70.12 Modelling Supporting Structure with Support Attributes Support attributes can be used to represent supporting structure which is not of interest aside from the stiffness contribution. Take for example a plate of glass resting on a rubber pad supported by a beam. Instead of modelling the beams with contact beneath the glass, a plate support attribute can be applied with an equivalent stiffness. This simplifies modelling and also allows the contouring of bearing stresses at the support points. A cross-section of a patch fitting holding two panes...
ST7-1.50.80 Modelling / Model Manipulation
0.4 MB	ST7-1.50.80.1 Model Manipulation Using the Online Editor This Webnote shows how a Strand7 model can be manipulated using the Edit/Online Editor tool. The Online Editor can be a very powerful way to modify attributes of a model in a tabulated format without the need to use the Graphical User Interface (GUI). The advantages are that a large number of parameters can be modified in a very short period of time as well as making element identification more efficient if the element number is known. The use of the Online Editor is best demonstrated using...
0.4 MB	ST7-1.50.80.3 Converting New Strand7 Models into Older Formats The latest release of Strand7 can open models from all previous Strand7 releases (i.e. there is backwards compatibility). However, older releases of Strand7 cannot directly open models created in newer releases. This document outlines how to open Strand7 models in older releases. Reverting a new model to an older release is simple. Open the model you want to revert in the new Strand7 release. Open File/Export, and select Strand7 Text File (*.txt) from the file type drop-down menu. ...
1.4 MB	ST7-1.50.80.6 Merging Two Models with Copy-Paste There are several ways to import one model into another. The simplest and most powerful is using the Copy-Paste functionality. Everything in one model is selected and copied to the clipboard. The target model is then opened and pasted into. There are options for what is to be pasted, and where (including orientation and scale). Open the source model ST7-1.50.80.6 SHB Abutment.st7. This model represents the masonry/concrete abutments of the Sydney Harbour Bridge. Set multi-select mode...
1.0 MB	ST7-1.50.80.12 Importing and Exporting Strand7 Model Data with Spreadsheets This Webnote examines the exchange of Strand7 finite element model data with a spreadsheet. This method is useful for exchanging model information between Strand7 and other structural analysis software packages for which Strand7 does not offer import/export functionality. The Online Editor is used for this purpose. This discussion focusses on the import of finite element model data into Strand7, although the discussion is also applicable to the export of models from Strand7.
0.8 MB	ST7-1.50.80.16 Removing Small Area Plates with the Online Editor This Webnote illustrates a method for detecting and removing plate elements with very small area. This is also applicable to brick elements with very small volume or beam elements with very small length. If these elements are sufficiently small, they can have a significant impact on the local stress field due to round-off or ill-conditioning.
0.9 MB	ST7-1.50.80.17 Aligning Beam Elements This Webnote examines the beam alignment tools. The beam axis system is used to define section properties, beam attributes, and beam result quantities such as force, moment, stress and strain results. The alignment of beams in a certain direction or in a consistent manner is a common modelling requirement. Strand7 provides several tools for changing the orientation of beam elements and alignment of their cross section.
ST7-1.50.90 Modelling / Restraints
2.7 MB	ST7-1.50.90.1 Modelling Symmetry Many structures exhibit some degree of symmetry. This can sometimes be exploited such that only a portion of the model need be represented in FEA, reducing the time to get solutions or freeing up resources for a more refined mesh. In order to exploit this symmetry, both the geometry and loading must be symmetric. Symmetry can be expressed as a fraction of the structure which remains once all redundant sectors are removed. / / / The resulting sector shown below is obviously much...

1.1 MB

ST7-1.50.10.1 Surface Automeshing Geometry and Hex Extrusion
It is often optimal to use a combination of automeshing and manual meshing. This Webnote covers an example of a reinforced end detail of a steel pile, which is first automeshed then extruded into a solid hexahedral mesh. The given geometry consists of 6 faces. These faces partially overlap, which will have to be corrected before automeshing can be successful. The 3D mesh to be built is shown below. Open ST7-1.50.10.1 Cruciform.st7. Use Tools/Geometry Tools/Graft Edges to Faces. ...

1.4 MB

ST7-1.50.10.2 Surface Automeshing an Excavator Assembly
The Strand7 automeshing module enables you to rapidly mesh imported CAD geometry. The geometry tools in Strand7 allow you to split and heal geometry to prepare it for automeshing when the initial imported geometry is lacking enough definition for FEA purposes. The geometry for this example is shown at right. The Webnote covers: Importing and cleaning CAD geometry Application of attributes to geometry Default automeshing Automesh quality assurance and common pitfalls The focus...

1.8 MB

ST7-1.50.10.5 Reducing Solid Geometry to Surfaces for Plate Meshing
The document demonstrates geometry manipulation techniques within Strand7 which can be used to produce geometry suitable for plate meshing from solid CAD geometry. A model of a tank is used to demonstrate this reduction in geometric complexity. The solid geometry of the tank is shown below. Solid geometry essentially has more than double the number of faces needed to produce a surface mesh. In this example, the inner surface of the tank touches much less than the outer surface, so we will...

4.9 MB

ST7-1.50.10.6 Solid Automeshing Multiple Connected Bodies
It is common when solid automeshing to have geometry which shares an interface with another part to which it is integrally connected. The model geometry is shown at right. It consists of an irregular stack of blocks, which could be bonded or just in contact. The overall modelling procedure will be to import the geometry, clean it up and mesh it such that there is a common node pattern at the interface between each body (compatible meshes). If each of the blocks is a fully enclosed solid which...

1.3 MB

ST7-1.50.10.7 Generating Geometry in Strand7
Strand7 offers a range of tools to help create and manipulate geometry in preparation for automeshing. These tools are not intended as an alternative to a CAD package, however, they offer sufficient functionality to generate various basic geometries from scratch, and more importantly, to make minor additions and modifications to imported CAD geometry - this can often avoid the need to go back to the CAD package to correct unmeshable geometry.

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ST7-1.50.10.9 Geometry Creation of a Cast-in Bearing Plate Bracket
Often engineers must design custom components when detailing structural connections or member supports. As this bracket is fairly small in size and geometrically simple, manual meshing is certainly a feasible option, however given the speed at which three dimensional models can be produced in any number of available CAD packages, and the simplified modelling allowed by the Automeshing tool in Strand7, the latter approach will be outlined here. In order to simplify the model, rather than modelling...

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ST7-1.50.10.16 Overview of Geometry Tools
Creating meshes to simulate complex geometry can be very time consuming. The geometry importer, geometry tools and automeshing tools make it possible to convert CAD created geometry into an FEA model. This Webnote focuses on the geometry tools and how they can be used to process the geometry imported from a CAD package to be suitable for automeshing. Some content of this Webnote is also covered in the Strand7 Online Help and Strand7 Tutorials, which can be consulted for extended description...

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ST7-1.50.10.20 Checking and Correcting Brick Faces
Assessing the quality of a surface representation of a brick mesh can be achieved by creating plate elements on the surface. These plates can then be measured and inspected. They can also be left in the analysis if their properties are set such that they do not influence the solution (e.g. by setting their modulus or thickness to a very small value). The example model is from ST7-1.40.70.15 Engine Head Gasket Analysis, in which it is analysed using the nonlinear static solver for the contact...

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ST7-1.50.20.1 Meshing a Conical Surface by Projection
This Webnote shows how to create a high quality mesh on a conical surface by projecting a mesh from a flat surface. This procedure assumes that you have a high quality mesh on a quarter of a circular plate, as shown at right. The mesh can be found in ST7-1.50.20.1 Cone_Base.st7. Create a cylindrical coordinate system with the origin at the corner of the quarter circle model and the cylindrical Z axis parallel to the global Z axis. Create a node which represents the apex of the cone,...

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ST7-1.50.20.2 Meshing a Plate with a Hole
This document steps through the procedure required to create the mesh for a plate with a hole in it. One method for refining the mesh around the hole will be discussed. The example will build a plate 600 mm long by 400 mm wide. A hole 100mm in diameter is located directly at the centre. Due to the symmetry of the plate, only one quarter of the full model needs to be created. The full mesh can be created later by mirroring the quarter model. Select File/New from the main menu and set the...

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ST7-1.50.20.3 Meshing a Solid Cylinder
This Webnote provides an example of manual mesh generation. Strand7 meshing tools are used to create the mesh for a solid cylinder, show on the right. Only a quarter of the cylinder is modelled due to symmetry. Create a new file with length units of Nmm. Right-click the Show/Hide Snap Grid button and enter the parameters shown. Enter the Create tab, select Quad4 and click OK. Hide the snap grid. Select Tools/Grade Plates and Bricks from the main menu. Using the grade option...

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ST7-1.50.20.4 Meshing a Pipe Elbow and Flange
This document outlines the procedure for creating a 90 pipe elbow using plate elements. This procedure could be adapted to model an elbow of any angle. It could also be adapted for use with beam or brick elements. The pipe geometry is shown on the right. A straight section of pipe mesh is provided and a 90 elbow is to be modelled. The flange is a 10 mm annulus on the end of the elbow. The initial straight section of the pipe has been provided in the file ST7-1.50.20.4 StraightPipe.st7. ...

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ST7-1.50.20.5 Intersecting Cylinders
This Webnote presents a method for creating a plate mesh representing two intersecting cylindrical surfaces using advanced manual meshing tools available in Strand7. Irrespective of whether the two cylinders are of the same or different diameters, the complex geometry at the intersection requires some planning to avoid poorly shaped elements. The best approach is to initially generate as coarse a mesh as possible and to refine it after the geometry has been correctly adjusted. Fillets...

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ST7-1.50.20.6 Extrusion Meshing in Multiple Directions
Some solid parts can be made of multiple intersecting extruded parts. In these cases it may be desirable to create an extruded Hexa8 or Hexa20 mesh instead of an unordered Tet10 mesh, because the number of nodes for a given accuracy may be greatly reduced. The geometry shown below can be extrusion meshed. It could be modelled using two extrusion directions, one for the stub and one for the supporting base. Firstly, it is important to plan out the extrusion sequence. Hold shift and hover over...

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ST7-1.50.20.7 Creating Cylindrical Features in an Existing Mesh
This document describes a general method for creating features that have circular or cylindrical shape. Typically this can be achieved by performing mesh manipulation with reference to a Cylindrical UCS defined at a convenient location. Some mesh adjustment may be required after a feature is added to the mesh to ensure mesh compatibility. In this example a 100 mm diameter pipe, representing a nozzle, is added to the top of a tank. The creation of circular or cylindrically shaped features is...

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ST7-1.50.20.8 Forming Compatible Mesh via Extrusion to Surface
In many real life structures, the connection detail between two components is not orthogonal, and may occur on a non-flat plane. This introduces some complexity into the modelling approach required to produce a compatible mesh. It is possible to produce a compatible mesh by using a variety of Strand7 tools. We will be examining an example of a connection between two pipes that meets at an angle. To simplify the mesh manipulation, the plate elements representing the main pipe and side pipe are...

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ST7-1.50.20.9 Modelling a Helix or Spiral
Modelling a helix or spiral in Strand7 can be done using Tools/Extrude/By Increment with a cylindrical UCS. First, create a cylindrical UCS at the centreline of the helix. Create a new UCS using Global/Coordinate Systems. Choose Cylindrical under System. Choose ZX under Type, or choose the plane which appropriately aligns the Z axis with the axis of the helix. If you have a node at the centreline, activate the Origin node hotpointer and select the centreline node. Click Apply. Create...

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ST7-1.50.20.10 Advanced Grading Techniques
This Webnote examines manual mesh refinement techniques using the Grade Plates and Bricks tool. An important part of building a finite element model is mesh refinement around areas of stress concentration, changes in geometry, or in other areas of interest. The Grade Plates and Bricks tool can be used to define the transition from a coarse mesh to a fine mesh, whilst ensuring that all elements are fully connected and retain acceptable aspect ratios. Strand7 offers many options to mesh these transitions, for example, to go from four elements to two or from three elements to one.

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ST7-1.50.20.11 Creating Interface Elements between Coincident Geometry
This Webnote illustrates operations and tools for creating interfaces between component parts, such as is required for the analysis of contacting bodies, or simply for disconnecting parts that have been zipped together. Although the physical parts may actually be coincident and may have been modelled in that way in a CAD program, for FEA purposes it is often necessary to introduce a small physical gap between the parts so that contact or other interface elements may be inserted.

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ST7-1.50.20.12 Interfacing Different Element Types
This Webnote examines the modelling considerations required to connect different element types - beams, plates, and bricks. In a mesh connecting different element types, simple element-to-element connection at the node may not transfer all load components correctly. Additional interface entities can be introduced to ensure compatibility of all degrees of freedom at the interface.

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ST7-1.50.20.14 Using the Points and Lines Tool to Build Models
This Webnote examines the node and beam element creation tools available in the Points and Lines tool. The dialog corresponding to this tool includes a range of options for creating nodes and beam elements in geometric configurations such as parabolas, circular arcs, as well as features like fillets and tangent lines. The tool also offers options to create construction features based on existing entities, such as finding the centre of a circular arc, and extending existing lines.

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ST7-1.50.20.16 Advanced Extrusion Meshing
This Webnote examines the Strand7 advanced extrusion options. Strand7 has the following extrusion options.

by Increment;
by Direction;
by Projection;
by Thickness;
by Line; and
to Absolute.

The Extrude by Increment and Extrude to Absolute options are the most commonly-used options in manual meshing. This Webnote presents some applications of all the extrusion options and gives the user some modelling tips about using these options in modelling.

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ST7-1.50.20.18 Modelling Intersecting Pipes with Hexahedral Elements
This Webnote illustrates techniques to manually create a mesh of intersecting pipes using 20-noded hexahedral elements. Tools such as extrude by projection, fillet plates and subdivide are used to produce the final mesh. Create two beam elements connected at right-angles. This represents a cut on the XY-plane where the outer surface of the branch pipe (vertical beam) meets the outer surface of the main pipe (horizontal beam), before the fillet is applied. Create a Cylindrical UCS aligned...

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ST7-1.50.30.1 Wind Loads on Shell Elements
Wind loads are often expressed in terms of force per unit length, and often vary with respect to height. It is quite easy to apply this sort of loading to a beam element using a distributed force, but applying equivalent wind loading to a shell element mesh takes some additional consideration. This document outlines how to apply an equivalent varying wind load to both beam and shell elements. A 1.5 m diameter tower is considered. Given a wind load of 30 kgf/m at a height of 4 m, and 100 kgf/m...

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ST7-1.50.30.2 Applying Moments to a Brick Mesh
3D solid elements (otherwise referred to as brick elements) do not contain rotational degrees of freedom in the element formulations. Each node in a brick element has only three translational degrees of freedom, meaning that the displacements DX, DY and DZ are calculated, while the rotations RX, RY and RZ (and corresponding moments) are not considered. If one were to apply a point moment directly to a brick mesh, it would be ignored as reflected in the solver log file Warning 6.

5.2 MB

ST7-1.50.30.3 Load Patches for Area Load
Area Load (or Floor Load), as referred to by some other engineering software packages, is equivalent to Load Patches in Strand7. In this Webnote we look at how load patches can be applied to model these situations. However, since the patch plates in Strand7 are very flexible, they can also be applied to non-planar meshes in 3D space; some examples are illustrated in this Webnote. The following structure is provided: A floor live load of 30 kPa is to be applied to the structure. Open the...

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ST7-1.50.30.4 Using the Moving Load Module
This Webnote outlines the use of the Strand7 Moving Load module for the modelling of transient loads moving along a path, the generation of load cases relevant to the possible positions of loads moving along a path, and to create static combination of loads moving along a path that minimises or maximises a specified response variable. Whilst each of these capabilities addresses different analysis types, central to them all is the definition of moving loads in a Load Path Template. In Strand7,...

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ST7-1.50.30.6 Using Normal Pressure to Fold a Box
The plate normal pressure attribute updates the direction of applied load as the structure deforms in a geometric nonlinear analysis. This means it can be used to apply load which causes structure to fold or wrap around other structure. In this Webnote we examine the folding of a box from a flat creased aluminium plate. The load is then released and the spring-back effect is measured. The starting planform shape of the box is shown at right. The model needs to have contact elements defined...

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ST7-1.50.30.8 Global Pressure Attribute Projection Options
This Webnote examines the load projection options for Global Distributed Force and Face Pressure attributes. The projection options dictate whether the total surface area or only the projected area of the element is used to calculate the total applied load. For area projection two methods are considered, namely projection in the direction of each load component, and projection in the direction of the load resultant.

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ST7-1.50.30.14 Balancing Load in Pressure Vessels with Openings
When modelling contained pressure loads that act on the structure, it is important that the load be balanced to model the physical reality accurately. That is, if there is an opening in the pressurised body, the lack of applied pressure on the opening (due to lack of finite elements that cover up these openings) will result in a large force imbalance. This effect is analogous to that of a propelling nozzle.

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ST7-1.50.40.1 Multi-Body Contact of a Rubber Bushing Assembly
There are several ways to connect multiple bodies to form contact surfaces. We will cover the case where the bodies are completely separate and have meshes which do not necessarily line up across the gaps between them. A rubber bushing used to restrain a window pane is analysed. It consists of 5 parts, one of which is a co-moulded steel-rubber bushing. The analysis we will perform on the bushing assembly is Axisymmetric. Create a new file. Set the units to Nmm. Import the file Bushing...

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ST7-1.50.40.2 3D Solid Multi-Body Contact
A sliding joint model is built by extrusion and automeshing methods. Contact is defined between the two bodies to determine the response of the multi-body system. Open ST7-1.50.40.2 Sliding Joint.st7. Note that there are two groups defined (Global/Groups). Turn off the group Stub and Base. Select the face which defines the cross-section of the track. Automesh the face with an edge length of about 2.4 mm using Tools/Automeshing/Surface Mesh. Extrude this mesh to 120 mm length in...

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ST7-1.50.40.4 Defining Contact Interfaces
Contact between multiple bodies in Strand7 is achieved using contact elements, which are a type of beam element. Whenever possible, it is best to use node to node contact, which is simply a contact beam element connecting two nodes. This is generally done in situations where there is a regular mesh, or the mesh on either side of the gap is the same, facilitating extrusion of contact beam elements between them. In the model shown at right, contact has been defined between the nodes on the two...

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ST7-1.50.40.5 Determining Appropriate Contact Stiffness
Contact is modelled in Strand7 using a special type of beam element. These beam elements react load nonlinearly, and in proportion to axial compression. The stiffness of these contact elements can affect the solution results accuracy and convergence. There are many physical situations that may be modelled with various configurations of contact elements. This Webnote aims to provide a guideline of what the axial stiffness value should be. Refer to ST7-1.57.20.8 Contact Element Fundamental...

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ST7-1.50.40.8 Sliding Contact
This Webnote introduces a technique that can be used to model sliding contact with pre-strained cutoff bar elements. Examples including pedestrian step loading, sliding of an interference fit, and reeling of a cable onto a spool are presented. We will use the following example to introduce the idea: A person of mass of 70 kg walks across a simply-supported steel beam 8 m long with 1000x100x10 mm rectangular hollow section. Create a new model and choose Nmm as the unit system. Create...

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ST7-1.50.50.1 Bolted Joints
Bolted joints can be modelled using Strand7 with varying levels of detail depending on the level of accuracy and local detail required in the analysis. Five options are presented, each with increasing levels of complexity.

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ST7-1.50.50.2 Beam End Releases
Beam end releases are provided as a beam element attribute in Strand7. These attributes can be applied to one or both ends of a beam element. Both translations and rotations can be independently released to model a variety of joint configurations. Where no end release is applied, two beam elements that share a node are modelled as being welded together. Using end release attributes, ends of beam elements can be fixed (no end release), partially released (where a connection stiffness is specified),...

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ST7-1.50.50.3 Tapered Beams
It is common to use beams which are tapered in engineering structures. One approach for modelling a continuous tapered beam is to use a sequence of untapered beam elements of varying size as shown below. This modelling approach could take considerable time for models with many tapered beams, as the accuracy of the solution may require many stepped beams. However, to reduce modelling time and solution time, and to improve accuracy, the beam Taper attribute may be applied to beam elements....

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ST7-1.50.50.4 Modelling with Cables
This Webnote examines different modelling approaches for cables and slender members with only axial capacity. The modelling consideration of tension-only capacity is also examined. Such cables and slender members can be modelled using Cable, Truss and Cutoff Bar type Beam elements in Strand7.

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ST7-1.50.50.6 Using String Groups
The Beam String Group attribute is used to model a continuous chain of truss type beam elements sliding through frictionless connections at nodes. The attribute ensures that a constant axial force develops in all the elements in the same string group. A common application of the attribute is to model massless cables (or strings) such as pulley systems, lifting sling cables, and pre-stressed steel tendons in reinforced concrete. This Webnote examines the Beam String Group attribute and its modelling applications.

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ST7-1.50.50.8 Simplified Spline Contact and Fatigue Analysis
In this Webnote we model the end of a winch drum which has a 60 mm diameter spline with 50 teeth. The effect of the spline is all that is needed the local stress in the teeth of the spline are not of interest. Fatigue analysis of the hub is the primary concern. Thus, we can use a simplified approach which gives an accurate coupling of the input shaft and winch, while maintaining a reasonably small model size. The interface between the male and female parts of a spline is complex. The gap...

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ST7-1.50.50.18 Beam Element Orientation
This Webnote discusses how beam elements are orientated in Strand7, together with methods for changing the orientation. The orientation of both Beam2 and Beam3 elements is presented. By default, Strand7 beam elements are aligned according to the principal axes of the cross section. Principal axes for an I-section, as shown in the Geometry tab of the Beam Property dialog, are illustrated at right. The orientation of the Beam2 element is fully specified by the definition of two non-coincident...

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ST7-1.50.60.1 Link Types
The various link types available in Strand7 are summarized below, including example uses. ...

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ST7-1.50.60.2 Link Forces
Links do not produce output like other FEA entity types (e.g. plate elements). We must instead extract the forces from links using one of two techniques, which are outlined below. The first involves Element Node Force, which is used to create free body diagrams at the link interface. The second makes use of Node Reaction output, which holds the forces due to restraints and can be modified to extract link forces as well. Consider the plane stress model below, which is included as ST7-1.50.60.2...

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ST7-1.50.60.3 Using Attachment Links
Although it is generally preferable to have full mesh compatibility between connected parts, in practice this is sometimes very difficult, if not impossible. Attachment attributes offer a versatile way of joining dissimilar meshes so that displacement compatibility is enforced by multi-point constraint equations that are automatically generated.

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ST7-1.50.60.5 Using Master-Slave Links
Master-Slave links are often misused, which can lead to non-physical behaviour. This Webnote outlines typical valid uses of the Master-Slave link, illustrates how the Master-Slave link differs from the Rigid Link, and summarises some of the common pitfalls of using Master-Slave links.

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ST7-1.50.60.7 Master-Slave Link Considerations
Master-Slave links provide a method of directly relating the degrees of freedom of two nodes in the mesh. These link types are normally intended to connect small gaps. Since the length of the link is not considered, usage over large gaps can lead to some non-intuitive results. This Webnote outlines the behaviour of Master-Slave links in some specific situations. From the point of view of moment calculations Master-Slave links are effectively of zero length. Consider the top mechanism shown...

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ST7-1.50.60.8 Using Links to Model Rigid Diaphragms
Certain structural members can be modelled as having infinite in-plane stiffness, and zero out-of-plane stiffness. This is typically done in the analysis of buildings, in which the floors are assumed to act in this way during seismic events. To achieve this, Strand7 provides a special type of planar rigid link cluster, in which the plane with infinite stiffness is specified by the user. A simple example is developed in which the floors of the six storey building from ST7-1.40.35.22 AS 1170.4-2007...

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ST7-1.50.70.1 Beam End Release and Node Displacement in GNL Analysis
This Webnote describes the relationship between the beam end release results and nodal displacement for linear and geometric nonlinear (GNL) solution cases. The focus here is on the rotational end release attribute, but the discussion is also applicable to the translational end release attribute. The default joint condition for a beam element in Strand7 is that of a welded joint. Strand7 has two Beam End Release attributes: one is the translational end release and the other is the rotational...

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ST7-1.50.70.2 Beam Bending and Nodal Rotational Stiffness
This Webnote illustrates the changing bending moment at the ends of beams subjected to uniformly distributed loads due to the effect of nodal restraints and joint connections. Consider a beam subjected to a uniformly distributed load as shown in the illustration. If the ends of the beam are pinned (nodes assigned zero rotational stiffness) then the bending moment at these ends is zero. If the ends of the beam are fully fixed (nodes assigned infinite rotational stiffness) then the bending...

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ST7-1.50.70.3 Modelling Soil with Support Attributes
When modelling a structure which is supported by soil, it is often simpler to model the soil with a support attribute. These attributes model the linear elastic response of a supporting medium. This Webnote outlines the basic procedure to apply supports equivalent to that of the surrounding grade. Support attributes only represent normal support; shear stiffness is not possible using support attributes alone. Support attributes can be applied to all element types. When applying brick face...

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ST7-1.50.70.5 Contouring Nodal Attributes
Strand7 allows the automatic contouring of element attributes, but not nodal attributes. However, there is a way to contour nodal attribute values on elements by using the Online Editor, Excel and a user defined nodal contour file. A complex nodal loading is applied to the nodes of some plate elements shown at right for the purpose of demonstrating nodal attribute contours. This method applies to any other nodal attribute, and also to brick or beam elements. The following general procedure...

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ST7-1.50.70.9 Assigning Attributes to Geometry
After importing CAD geometry, attributes can be applied directly to the geometry. These attributes are then automatically inherited by finite elements after automeshing. Advantages of applying attributes to geometry include:

Work is factored out when successive models are required (for example, as a part of a mesh refinement sensitivity study); and
The geometry stage typically has far fewer entities and can therefore be easier to work with.

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ST7-1.50.70.10 Assigning Attributes using Equations
Strand7 attributes can be applied using an equation which references the currently active coordinate system directions. Any UCS type (cartesian, cylindrical, toroidal or spherical) can be used. This functionality can be used to define non-uniform attributes on nodes and elements. Attributes which are applied with an equation only reference the equation at time of application. If the UCS is changed or the entity is moved the attributes will remain unchanged. Create a cylindrical UCS centred...

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ST7-1.50.70.12 Modelling Supporting Structure with Support Attributes
Support attributes can be used to represent supporting structure which is not of interest aside from the stiffness contribution. Take for example a plate of glass resting on a rubber pad supported by a beam. Instead of modelling the beams with contact beneath the glass, a plate support attribute can be applied with an equivalent stiffness. This simplifies modelling and also allows the contouring of bearing stresses at the support points. A cross-section of a patch fitting holding two panes...

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ST7-1.50.80.1 Model Manipulation Using the Online Editor
This Webnote shows how a Strand7 model can be manipulated using the Edit/Online Editor tool. The Online Editor can be a very powerful way to modify attributes of a model in a tabulated format without the need to use the Graphical User Interface (GUI). The advantages are that a large number of parameters can be modified in a very short period of time as well as making element identification more efficient if the element number is known. The use of the Online Editor is best demonstrated using...

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ST7-1.50.80.3 Converting New Strand7 Models into Older Formats
The latest release of Strand7 can open models from all previous Strand7 releases (i.e. there is backwards compatibility). However, older releases of Strand7 cannot directly open models created in newer releases. This document outlines how to open Strand7 models in older releases. Reverting a new model to an older release is simple. Open the model you want to revert in the new Strand7 release. Open File/Export, and select Strand7 Text File (*.txt) from the file type drop-down menu. ...

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ST7-1.50.80.6 Merging Two Models with Copy-Paste
There are several ways to import one model into another. The simplest and most powerful is using the Copy-Paste functionality. Everything in one model is selected and copied to the clipboard. The target model is then opened and pasted into. There are options for what is to be pasted, and where (including orientation and scale). Open the source model ST7-1.50.80.6 SHB Abutment.st7. This model represents the masonry/concrete abutments of the Sydney Harbour Bridge. Set multi-select mode...

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ST7-1.50.80.12 Importing and Exporting Strand7 Model Data with Spreadsheets
This Webnote examines the exchange of Strand7 finite element model data with a spreadsheet. This method is useful for exchanging model information between Strand7 and other structural analysis software packages for which Strand7 does not offer import/export functionality. The Online Editor is used for this purpose. This discussion focusses on the import of finite element model data into Strand7, although the discussion is also applicable to the export of models from Strand7.

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ST7-1.50.80.16 Removing Small Area Plates with the Online Editor
This Webnote illustrates a method for detecting and removing plate elements with very small area. This is also applicable to brick elements with very small volume or beam elements with very small length. If these elements are sufficiently small, they can have a significant impact on the local stress field due to round-off or ill-conditioning.

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ST7-1.50.80.17 Aligning Beam Elements
This Webnote examines the beam alignment tools. The beam axis system is used to define section properties, beam attributes, and beam result quantities such as force, moment, stress and strain results. The alignment of beams in a certain direction or in a consistent manner is a common modelling requirement. Strand7 provides several tools for changing the orientation of beam elements and alignment of their cross section.

2.7 MB

ST7-1.50.90.1 Modelling Symmetry
Many structures exhibit some degree of symmetry. This can sometimes be exploited such that only a portion of the model need be represented in FEA, reducing the time to get solutions or freeing up resources for a more refined mesh. In order to exploit this symmetry, both the geometry and loading must be symmetric. Symmetry can be expressed as a fraction of the structure which remains once all redundant sectors are removed. / / / The resulting sector shown below is obviously much...