Static and Quasi-Static Analysis

There are a few key points that must be kept in mind while trying to simulate models containing NLFE components through a static or quasi-static analysis:

Applying Motion

Any applied motion must be applied slowly, preferably through the use of a STEP function to ensure that the analysis is successful. This is because in a static/quasi-static analysis, there are no inertial effects and so the displacement of an NLFE grid between two consecutive static steps is not limited by inertia or material properties. What this means is that if the motion is applied suddenly and in one shot, the analysis can result in wrong results or fail altogether. This is a good modeling practice not just for NLFE bodies, but for most MotionSolve models subjected to a static/quasi-static analysis

Further, a static simulation of your model is not successful, you may try to switch to a quasi-static analysis and apply any actuation motions using a STEP function, if applicable.

Reference Length

A good modeling practice is to setup your model for a static analysis such that the maximum displacement of any NLFE grid is not more than a reference length in each static iteration. A good reference length for your NLFE components(s) is the minimum length or span of a beam element, for example. The choice of this reference length depends on the model being simulated.

The above criteria can be enforced by

• Constraining your NLFE component(s) suitably such that large displacements are avoided
• Switching to a quasi-static analysis if large displacements are expected. This enables you to specify the step size which in turn will allow you to wield control over the displacements during the static analysis