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AutoFEM Analysis Dynamic Analysis |  |
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AutoFEM Analysis Dynamic Analysis | |
The dynamic analysis module of AutoFEM Analysis is used for calculation of changing in time stress state three-dimensional structures in AutoFEM Analysis. The module works with three-dimensional models and do not usually requires separate additional constructions for calculation of the three-dimensional model.
Buttons of dynamic study creation
In the dynamic analysis the mechanical system is considered under the action of a time-varying external influences of the forces, pressures, accelerations, etc. applied to the system. The examples of Dynamic analysis studies are shaft or spindle spin up, the vehicle passage on the bridge, seismic vibrations, filling of hopper with sand, etc. A stress state of the mechanical system will also change in time. Analysis of such situations is important in many practical cases as dynamic stresses and inertial forces can have a significant influence on the overall performance of the mechanical system. As a result of the dynamic study solution we receive the same calculation results as for the static analysis (displacements, stresses, factor of safety) but each result presented for a point in time corresponding to the set time interval and the specific time step interval. The system user has a possibility to see the system strains and stresses changes in time and to predict the system behaviour under the complex system of external changing in time influences.
A dynamic strength condition is formulated in the following way in the general case:
Stresses
that appear in the structure under the action of external forces applied to the structure must be less than the allowable stresses 
for the structural material with the use of a correction factor of safety SF by dynamic strength. 
As for the static analysis the main calculation results are displacements, stresses, factor of safety in time-varying function.
Mathematical statement of dynamic study by finite element method looks in the following way:
, (1)
where:
- symmetrical square matrix 
of the system stiffness,
- vector of generalized forces, applied in the system nodes,
C- symmetrical square matrix of the system damping,
- vector of generalized displacements, applied in the system nodes,
- vectors of generalized velocities and accelerations, applied in the system nodes.
From the point of view of mathematical implementation there are two main approaches to the solution of systems of equations arising in the description of dynamic studies: mode superposition and transitional process.
Input data for dynamic calculation differ according to the study type. Consider parameters of each type of dynamic studies separately.
See also: Dynamic Analysis, Direct Time Integration, Mode Superposition, Dynamic Analysis Steps, Time Settings, Integration Parameters, Assigning Initial Conditions, Damping of System, Thermal Effects, Analysing Results, Example of Dynamic Analysis