Stationary Analysis
You can consider a structural mechanics problem as stationary if the following two criteria are fulfilled:
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The loads vary so slowly that inertial forces are negligible. Problems of this type are referred to as quasi static.
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There are no explicit time dependencies in the material model. Viscoelasticity and creep have such time dependences.
To perform this type of analysis, you use a Stationary study step.
In many cases, there is a variation in the load, even though the solution for each value of the load can be considered as stationary. There are three conceptually different cases:
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The load values are independent; it is just a number of different load cases you want to compute. The load case handling functionality described in Load Cases is well suited for this purpose.
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You want to study a nonlinear problem where the solution is path dependent, or where the load must be increased in small increments in order to obtain a converged solution. In this case you should use the parametric continuation solver. Create a parameter under Global Definitions>Parameters, which you use to control the variation of the load. Then select Auxiliary sweep under Study Extensions in the settings for the Stationary solver. In the table for the auxiliary sweep parameters, add the load controlling parameter, and define its range of variation.
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In a multiphysics problem, another physical quantity might be truly time dependent but on a time scale that is “slow” from the structural mechanics point of view. This is usually the case with, for example, problems coupled to heat transfer or diffusion. If the problem also is such that the structural deformations do not affect the other physics, it will be unnecessarily expensive to solve also the structural problem in the time domain, irrespective of whether it is linear or nonlinear. In this situation, you should first solve the other physics in a time-dependent study and then the structural mechanics problem in a subsequent stationary study step using the time t as the parameter in the auxiliary sweep.
For an examples of how to set up such a study sequence, see for example Fluid-Structure Interaction in a Network of Blood Vessels: Application Library path Structural_Mechanics_Module/Fluid-Structure_Interaction/blood_vessel.
Constraints
A stationary problem is solvable only if the structure is sufficiently constrained. There must not be any possible rigid body modes. Thus, no stress-free deformation states are allowed.
For a more detailed discussion about sufficient constraints, see Rigid Body Motion.