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ST7-1.10 Linear

ST7-1.10.10 Linear / Statics

1.9 MB
ST7-1.10.10.3 General Model Troubleshooting
Before analysis, all the data in a finite element model should be carefully checked to ensure that:
1. it is representative of the structure being modelled;
2. it is applicable to the required analyses; and
3. the assumptions and approximations made are suitable.
At the completion of the analysis, and before in-depth interpretation of the analysis results, the solver messages should be studied. Finally, the results should be checked for reasonableness. This Webnote introduces the Strand7 features and tools that can be used for checking and troubleshooting finite element models, so that the above procedures can be more easily performed.
ST7-1.10.20 Linear / Dynamics

1.1 MB
ST7-1.10.20.9 Spectral Response Analysis
Spectral response analysis is typically used for calculating the linear elastic response of a structure subjected to random dynamic loading. In Strand7, random dynamic loading can be expressed in terms of either response spectrum or power spectral density (PSD) curves. Furthermore, the applied excitation can be either a base excitation (displacement, velocity or acceleration) or a dynamic load.  Suppose that an oscillator with a single degree of freedom (SDOF) is excited by an external action...

0.8 MB
ST7-1.10.20.12 Vibrational Analysis of a Wine Glass
The harmonic oscillation of a wine glass is a familiar phenomenon to many people. In this Webnote we recreate the harmonic behaviour of a Riedel Vinum Shiraz / Syrah glass. The natural frequency solver is used to recreate the tone generated by rubbing a moistened finger around the rim of the glass, and the linear transient solver is used to recreate the frequency spectrum seen in response to an impulse load. In both cases Strand7 results are compared with experimental results.

1.6 MB
ST7-1.10.20.13 Response Spectrum and Power Spectral Density
This Webnote compares two common techniques of dynamic analysis for stochastic inputs, Spectral analysis with a known Response Spectrum, and Spectral analysis with an input Power Spectral Density, against full transient solutions. The Spectral Response solver in Strand7 takes two different types of input to determine the response of the structure to random excitations: a Response Spectrum, or a Power Spectral Density function. In this Webnote, we demonstrate these different approaches...

0.6 MB
ST7-1.10.20.20 Static and Dynamic Stiffness
A common transfer function measurement is the Frequency Response Function (FRF). The aim of this Webnote is to give a brief overview of some of these functions, and to take a more detailed look at dynamic stiffness, which is a particular FRF.

2.0 MB
ST7-1.10.20.22 Compression-Only Footfall Harmonic Response Analysis
Footfall analysis on pedestrian-loaded structures is often performed using the Harmonic Response solver, which is used to determine the steady-state response of a structure to a given sinusoidal forcing load. Whilst it is tempting to simply apply the peak footfall load in such an analysis, this approach assumes that the footfall load acts in tension as well as compression, when in reality the step load is more like a half-sine wave.
The assumption that the load acts in both tension and compression is not necessarily a conservative one. There is more to the difference between a half-sine wave and a fully-reversing sine wave than the load magnitude. Whenever a discontinuous acceleration is applied, it can excite higher frequency modes than the frequency of the applied footfall load. Thus the footfall, while nominally acting around 2.0 Hz, can also excite natural frequencies with harmonics around 4.0 Hz, 6.0 Hz, 8.0 Hz, 10 Hz etc. (n x fstep).
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