Strand7 Software:  Release History:  Release 1.06

What's new in Strand7 Release 1.06

23 November, 2000

Comprehensive Verification Manual

This comes as a PDF file and documents numerous Strand7 benchmark models and results. Each benchmark is also included as a Strand7 file - over 300 Strand7 files are included.

Improved Solver Memory Usage

Under a multi-tasking environment like Windows, there is always an opportunity to improve an application's usage of resources such as memory. Further tuning of Strand7's memory usage has resulted in improved solver performance (about 20% faster than Release 1.05), particularly for large models.

Improved Bandwidth Minimizer

The bandwidth minimizer has been improved and now gives a new measure of the required memory, the "Maximum memory index". Minimize this value to minimize the amount of memory required by the solver.

New Tool: Adjust Mid-side Nodes

Sometimes, due to modelling operations, the mid-side nodes of quadratic elements (Plates and Bricks) are located at positions that are outside acceptable limits, possibly resulting in a singular element. This new tool automatically places the mid-side nodes at the geometric mean of the corner nodes. It also considers curved elements: in this case, the mid-side nodes are located on a cylindrical or spherical surface as appropriate.

Master-Slave Link in UCS

Master-Slave links may now be defined in any UCS. This greatly enhances the capability of the Link element. All the UCS types (Cartesian, Cylindrical, Spherical, Toroidal) are supported.

Select Free Entities

A new selection option, "Select Free Entities" is used to locate any entity that is not connected to other entities. The option is particularly useful for finding free-floating beam elements and contact elements.

Exclusive Toggles Button

The setting of the selection mode (Additive or Exclusive) is now easily accessible via a toggle button on the main tool bar.

Automatic Time Step

The Nonlinear Transient solver can now automatically reduce the time step to better capture the behaviour of contact problems.

Links Force Contribution to Reactions

Forces between nodes connected through links can now be included in the node reaction calculation.

Faster Brick Stress Averaging

This is particularly important for generating stress contours of automatically generated tetrahedral brick meshes.

New Grade Options

The two grade options shown may be applied to both plate and brick elements.

Automatic Superposition of Deformed and Undeformed Display

A single checkbox, "Add Undeformed" on the Displacement Scale Dialogue box now allows you to automatically superimpose both the deformed and undeformed meshes. With this option, you can also print the superimposed display.

New Shortcuts

The following shortcuts have been added:

Ctrl-Shift-A Show all entities (this is also available on the Right-Click Popup)
Ctrl-Tab Switch between open Strand7 models
Ctrl-G Show groups window
Ctrl-U Show units dialogue box
Ctrl-W Create node
Ctrl-E Create element
Ctrl-L Create link
Ctrl-Shift-W Show/hide whiteboard
Ctrl-R Open results file
Ctrl-Alt-T Attribute Display Options
Ctrl-Alt-E Element Display Options
Ctrl-Alt-V Screen View Options

New Configurable Log File Viewer

Previously, Strand7 launched Notepad or Wordpad as a way to view the solver log files. This approach was adequate for small files, such as those for linear static solutions, but for very long log files, such as nonlinear or transient solutions, it was often cumbersome. The new Log File Viewer provides a series of options allowing you to quickly show specific parts of the log file and hide others. In the example shown in the figure, only the convergence history for a nonlinear solution has been displayed.


Viewports define a new way to show and hide parts of the model. Viewports in Strand7 can be defined in any UCS, and any number of Viewports can be defined. For each Viewport, you can choose whether entities inside or outside the Viewport are to be Shown/Hidden. This mechanism provides a very powerful way to view different parts of the model at the same time. Viewports can be used in conjunction with or independently of Show/Hide by Group, by Selected, by Unselected and by Property.

DXF In / Out

In this release, DXF layers are mapped to and from Strand7 groups and DXF colours are mapped to and from Strand7 property types.

DXF Out Beam Sections

When exporting Strand7 beam models to the DXF format, a new option allows you to export the beam elements as Line, Section or Solid format. Section and Solid formats generate the full beam geometry so that it may be rendered in AutoCAD.

Negative Property Increments

All the tools that support a property increment (i.e. Copy, Extrude, etc.) now allow the property increment to be negative.

New Point Contact Type - Takeup Gap

The Takeup Gap can be used to simulate a takeup device. Such a device allows motion only in one direction, the free direction, as illustrated in the figure below.

This is different to the other contact types, such as Normal Gap where motion can occur in the fixed direction as long as motion has already occurred in the free direction. The Takeup Gap never allows motion in the fixed direction, irrespective of the amount of movement in the free direction. The fixed direction can be set via the Tension/Compression attribute. A more detailed explanation can be found in the online help.

Variation of Modulus, Stiffness and Conductivity with Time

All element property types now support the variation of modulus, stiffness and conductivity with time, in nonlinear transient (including heat transfer) solutions. This attribute can be useful for simulating the behaviour of structures where the material stiffness changes with time. An example is the curing of concrete.

Different Numeric Display Options for Pre-processing and Post-processing modes

You can now set two numeric display formats, one set for the pre-processing and another for the post-processing mode. This eliminates the need to continually change these settings whenever result files are opened and closed.

Friction Coefficient Behaviour

Whenever a friction coefficient greater than or equal to 1 is specified in the Point Contact property input, the frictional force transferred across the Point Contact is now not limited to the product of friction coefficient and axial force. This is a special mode that allows the modelling of contacts where once contact is established, no slip can occur.

New Beam Property Type - Connection

The new Connection beam type provides a simple mechanism to link any or all degrees of freedom between two nodes via a specified stiffness. This is similar to the Master/Slave link except that the connection is flexible not a rigid one. The Connection beam can be used in both linear and nonlinear analyses. For nonlinear analysis, each stiffness value may be coupled to a nonlinear Stiffness vs Displacement table. The element supports both nonlinear elastic and elasto-plastic behaviour. Note that this is not a beam element and therefore the relationship between shear and bending (i.e. V=dM/dx) does not apply.

Mass Participation Factor in Natural Frequency Analysis

The Natural Frequency solver can now calculate the mass participation factor of each mode in any specified direction. This information can be used in other modal analyses such as harmonic or spectral response.

Modal Damping Ratio in Natural Frequency Analysis

A new attribute on all the element property sets, the Damping Ratio, is now available. This is a dimensionless value (unlike Viscous Damping), that can be used to define the damping ratio for each material type. The Natural Frequency solver can use these values to determine the effective modal damping ratio for each mode. These data can then be used in other modal analyses such as harmonic and spectral response.

Normalize Graph Axes

The axes of any result graph can now be normalised.

New Preset Viewing Angles

The "Angles" dialogue box now includes additional preset angles so that each preset now has a Front and a Back option.

Change Graph Axis Titles

The axis lables of any result graph can now be changed.

Extrude Tool

The extrude tool now provides a list of available beam properties for selecting the target of extruded nodes.

Auto Assign Plate Offsets

Plate offsets can now be automatically assigned by an amount equal to half the thickness. This is particularly useful for offsetting the outer surfaces of adjoining plates of different thickness as is typical in molded components.

Laminate Lay-up Window

A number of improvements have been made to this window including:

* Undefined plies can now be inserted in the stack. These are ignored by the solver and the post-processing tools, but can be useful to insert so that a specific layer number is consistent across laminates with different number of plies.
* The engineering properties are dynamic and update automatically whenever a change is made to the lay-up. This allows easy checking and tuning of lay-ups.

* The lay-up display can be printed.

* Laminates now accept a user-defined transverse shear stiffness.

Select Entities from Result Listings and Online Editor

Both the Result Listings and Online Editor windows allow you to sort data in columns. It can be useful to be able to select entities with stress above a given value (say). By using the Results Listings window and sorting the data on the required column, you can then highlight the desired entities and automatically select them via the "Select Highlighted" option of the right-click popup. Upon closing the Results Listings window, these elements will be selected in the graphical display.

Show Node Offsets

When offsets have been applied, both beam and plate elements can now indicate the nodes to which the element is connected, by selecting the option in the Element Display dialogue box.

Show Ply Axes

In addition to the local plate (x-y) axes directions, the material axis directions of each ply can be displayed. This is available in both pre-processing and post-processing modes. Simply set the desired ply number and the corresponding material axes are shown for that ply.

New Display Option - Group Wireframe

All elements may now be displayed in wireframe mode, in the colour of the group.

Projection to Line - Equi-space Option

For all tools that project to a line, the "Equi-space" option can be used to ensure that the target nodes are equally spaced along the target line. This also works with extrusions generating quadratic elements - the mid-side nodes are correctly spaced.

Linear Static Solver - Select Load Cases to Solve

The Linear Static solver now allows you to select which load cases are to be solved.

Principal Stress Angle

The angle between the plate's local x-axis and the direction of the maximum principal stress is available in the Result Listings and in the element Peeking.

Displacement Scale - Relative to a Node

Deformed displays can now be relative to another node. This is particularly useful to visualize the local displacements that occur on a part of the structure that is undergoing a large rigid body displacement. In this case, greatly exaggerating the displacement scale is not useful, however, setting the movement relative to another node (the Reference node) clearly exaggerates the local deformations.

New Beam Property Type - Pipe

The new Pipe beam element allows the modelling of straight or curved pipes with circular cross-section.

The pipes support many new attributes including:

* Internal and external pressure.

* Internal and external temperature.

* Arbitrary radius, effectively modelling a curved beam.

In addition to the standard material properties, pipe element properties also support a "Fexibility Factor" that reduces the flexural stiffness of the pipe, and a "Fluid Density" attribute used in the calculation of the mass of fluid inside the pipe.

Plate Edge Release Attribute

Similarly to the beam elements, plate element edges may release their rotational stiffness along an edge, effectively generating a hinged edge connection. This simplifies the modelling of hinged connections.

Total Energy Summation

When contours of Strain Energy Density are requested, the total energy in the system is now also reported.

Show/Hide Links by Type

Similarly to showing and hiding elements by property, links can now be shown/hidden based on type.

Beam Axial Release in Nonlinear Analysis

The axial translational release of beams is now available in geometric nonlinear analysis.

Edit Links

Links can now be easily changed from one type to another or their attributes changed by using the "Edit Link Type" tool. The retrieve option, Ctrl-Click, also works here easily enabling you to extract the current attributes of any link, make changes and re-Apply.

Batch Solver

Any number of solutions can be placed on a batch queue for solving in sequence at a later time.

Graph of Relative Nodal Quantities

Nodal quantities such as displacement, velocity, acceleration, etc. can now be graphed relative to another node. This will make it possible to show relative displacement, velocity or acceleration between nodes.

New Hardening Rules for Beams

Beam elements, when used in elasto-plastic analysis can now conform to one of three different hardening rules: Isotropic Hardening, Kinematic Hardening and hardening based on the Takeda model. Previously only isotropic hardening was supported. More information about the differences between these can be found in the online help files.

Auto Intersect Beams

This tool is used to automatically split intersecting beam elements. It is very useful when importing frameworks constructed in CAD systems and the intersections have not been created. A single execution of the tool is able to detect and create multiple intersections occurring in any element.

Show Nodes by Group

Nodes can now be shown or hidden based on the visibility of groups.

Swap the Principal Axes on BXS Sections

The 11 and 22 axes can now be swapped to allow easier placement and orientation of BXS sections.

Harmonic Response Solver - Load can be a function of frequency

You can now assign a Frequency vs Factor table to each load case included in a harmonic analysis. This is used to scale the applied load as a function of frequency.

Increment Labels Available in Post Processing

The increment labels used to define the nonlinear load increments are now available in the Result Case drop-down list during post processing.

Easier Definition of Cylindrical Coordinate Systems

A new 2-point option allows the arbitrary orientation of the Theta=Zero direction of cylindrical coordinate systems located on the global Cartesian planes.

Termination of Eigenvalue Solutions

The iterations in the Natural Frequency and Linear Buckling solvers can now be terminated at the end of any iteration. The result files are created at the end of the current iterations even if all modes have not converged. This can be very useful in situations where the high-order modes cannot converge whilst the low-order modes have converged.

Thickness of Attribute Displays

The thickness of most attributes (e.g. node forces) can now be specified. This is particularly useful when printing to high resolution printers.

Automatically Interpolate Beam Sections

A new tool can be used to automatically create a series of beam elements where the section geometry is linearly interpolated between values specified at the ends. The tool will search the beam properties to find a beam section that matches the specific requirement - if the required section cannot be found, a new one is automatically generated.

Delete Unused Groups

Groups that do not contain entities can now be automatically deleted.

Launch Solver in Quiet Mode

You can now launch the solver with both the progress bar and the log file messages switched off. This is particularly useful for small models or models requiring iterative solutions where the screen update can significantly affect the run time

Enhanced File Browser

The file browser now gives more information about the available models, including information about available result files - this is shown graphically via a small contour legend symbol and also in the right-click popup/Information.

Customisable Defaults

All screen, entity and attribute settings can be stored to a defaults file so that each new model will utilize those defaults. You can configure the default colours, including the background, the size and type of element and attribute displays and other preferences you may like to set as defaults. Multiple configuration files can exists and you can select, modify or create a new one, at any time.

Displacement Vectors

In addition to the previously available velocity and acceleration vectors, you can now plot vectors of displacement.

Improved Animator

The Strand7 Animator has received a general overhaul. In particular, the animator is now less attached to Strand7 - you can animate multiple models simultaneously and the animator window can be resized on-the-fly. In addition, you can now save a self-running animation that can be run on any computer and does not need Strand7. This will make the distribution of results to clients even easier.

Cut and Paste is Groups-Aware

When you perform cut-copy-paste operations within Strand7's internal clipboard to paste entities and attributes, you can now use the "Match Group Names" option to ensure that elements are pasted into groups with the same name - even multi-level group hierarchies are correctly mapped.

Maximum Response in Transient Solutions

Although Strand7's general-purpose envelope function can be used to find envelopes of virtually any quantity, a new function in the Transient solver provides a summary in the log file, of result maxima over the specified time domain.

Rayleigh Factors Specification

Rayleigh damping can now be specified by directly entering the Rayleigh constants. The input of frequencies and damping ratios is still available.

Reduced Integration for 2D Plates

Plate elements (Quad8 and Quad9) in Plane Stress, Plane Strain and Axisymmetric solutions can now be under-integrated. This can be useful in Elasto-plastic analyses.

Plate Pre-Stress Attribute

This now allows the input of 3 components. In addition to the previously available x and y values, a z value can now be entered for plane strain and axisymmetric elements.
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