Structural analysis is the most common application of FEA simulation software.  Engineers have been using FEA (finite element analysis) software for well over thirty years to solve structural models.  Beginning in the early 1970’s, ANSYS, Inc. is one of the oldest and highly respected developers of FEA software in the world.  ANSYS software is the most widely used FEA software worldwide and is used just about every industry that employees mechanical engineers.

When selecting the appropriate structural FEA package from ANSYS, there are a number of structural analyses that need to be considered.

Static Structural Analysis

Flexible Dynamic Analysis

Rigid Dynamic Analysis

Modal Analysis

Harmonic Analysis

Linear Buckling Analysis

Random Vibration Analysis

Please feel free to contact us to discuss the various options and budget considerations.  You may also wish to review the ANSYS Capabilities Guide.

Another common consideration is whether or not the analysis includes one or more nonlinear effects:

Geometric nonlinearities - If a structure experiences large deformations, its changing geometric configuration can cause nonlinear behavior.

Material nonlinearities - A nonlinear stress-strain relationship, such as metal plasticity is another source of nonlinearities.

Contact - Include effects of contact is a type of “changing status” nonlinearity, where an abrupt change in stiffness may occur when bodies come into or out of contact with each other.

Please feel free to contact us to discuss the various options and budget considerations.  You may also wish to review the ANSYS Capabilities Guide.

Static Structural Analysis

A static structural analysis determines the displacements, stresses, strains, and forces in structures or components caused by loads that do not induce significant inertia and damping effects.  Steady loading and response conditions are assumed; that is, the loads and the structure's response are assumed to vary slowly with respect to time.

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Flexible Dynamic Analysis

Flexible dynamic analysis (also called time-history analysis) is a technique used to determine the dynamic response of a structure under the action of any general time-dependent loads. You can use this type of analysis to determine the time-varying displacements, strains, stresses, and forces in a structure as it responds to any combination of static, transient, and harmonic loads. The time scale of the loading is such that the inertia or damping effects are considered to be important. If the inertia and damping effects are not important, you might be able to use a static analysis instead.

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Rigid Dynamic Analysis

Rigid dynamic analysis is a technique used to determine the dynamic response of an assembly of rigid bodies linked by joints and springs. You can use this type of analysis to study the kinematics of a robot arm or a crankshaft system for example.

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Modal Analysis

A modal analysis determines the vibration characteristics (natural frequencies and mode shapes) of a structure or a machine component. It can also serve as a starting point for another, more detailed, dynamic analysis, such as a transient dynamic analysis, a harmonic response analysis, or a spectrum analysis. The natural frequencies and mode shapes are important parameters in the design of a structure for dynamic loading conditions.

You can also perform a modal analysis on a prestressed structure, such as a spinning turbine blade

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Harmonic Analysis

In a structural system, any sustained cyclic load will produce a sustained cyclic or harmonic response. Harmonic analysis results are used to determine the steady-state response of a linear structure to loads that vary sinusoidally (harmonically) with time, thus enabling you to verify whether or not your designs will successfully overcome resonance, fatigue, and other harmful effects of forced vibrations.

This analysis technique calculates only the steady-state, forced vibrations of a structure. The transient vibrations, which occur at the beginning of the excitation, are not accounted for in a harmonic response analysis.

In this analysis all loads as well as the structure’s response vary sinusoidally at the same frequency. A typical harmonic analysis will calculate the response of the structure to cyclic loads over a frequency range (a sine sweep) and obtain a graph of some response quantity (usually displacements) versus frequency. “Peak” responses are then identified from graphs of response vs. frequency and stresses are then reviewed at those peak frequencies.

Linear Buckling Analysis

Linear buckling (also called as Eigenvalue buckling) analysis predicts the theoretical buckling strength of an ideal elastic structure. This method corresponds to the textbook approach to elastic buckling analysis: for instance, an eigenvalue buckling analysis of a column will match the classical Euler solution. However, imperfections and nonlinearities prevent most real-world structures from achieving their theoretical elastic buckling strength. Thus, linear buckling analysis often yields quick but non-conservative results.

A more accurate approach to predicting instability is to perform a nonlinear buckling analysis. This involves a static structural analysis with large deflection effects turned on. A gradually increasing load is applied in this analysis to seek the load level at which your structure becomes unstable. Using the nonlinear technique, your model can include features such as initial imperfections, plastic behavior, gaps, and large-deflection response. In addition, using deflection-controlled loading, you can even track the post-buckled performance of your structure (which can be useful in cases where the structure buckles into a stable configuration, such as "snap-through" buckling of a shallow dome).

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Random Vibration Analysis

This analysis enables you to determine the response of structures to vibration loads that are random in nature. An example would be the response of a sensitive electronic component mounted in a car subjected to the vibration from the engine, pavement roughness, and acoustic pressure.

Loads such as the acceleration caused by the pavement roughness are not deterministic, that is, the time history of the load is unique every time the car runs over the same stretch of road. Hence it is not possible to predict precisely the value of the load at a point in its time history. Such load histories, however, can be characterized statistically (mean, root mean square, standard deviation). Also random loads are non-periodic and contain a multitude of frequencies. The frequency content of the time history is captured (spectrum) along with the statistics and used as the load in the random vibration analysis. This spectrum, for historical reasons, is called Power Spectral Density or PSD.

In a random vibration analysis since the input excitations are statistical in nature, so are the output responses such as displacements, stresses, and so on.

Typical applications include aerospace and electronic packaging components subject to engine vibration, turbulence and acoustic pressures, tall buildings under wind load, structures subject to earthquakes, and ocean wave loading on offshore structures.

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