When to use Nonlinear Analysis?

Nonlinear Analysis

A Linear Static analysis can be performed on a problem if the following assumptions are valid:

• The material is linear elastic, where the geometry will return to its original shape if the load is removed.
• Deformations are small in relation to the dimensions of the model.
• Loads and restraints are constantly applied to the model, without change in magnitude or direction. Also, the loads do not cause separate parts to come into contact with one another

A Linear Static solution is not valid if any of these points are violated. The relationship between the loads (generalized force) and the response (generalized displacement) becomes nonlinear, and a Nonlinear Analysis must be performed in order to get accurate results that reflect true-to-life behavior.

To determine if you need to do a nonlinear analysis, the following key questions should be answered:

• Has the maximum stress exceeded the yield stress for the material? Or are any of the material properties modified as a consequence of the stress level reached?
• Are the deflections large? (rough guide: if deflections are close to the thickness of the material then the deflections are large).
• Is stress stiffening/stress softening occurring?
• Are there dynamic or inertial effects?
• Is a no-penetration contact area expected to change shape or size during the simulation?
• Is a material experiencing creep or viscoelasticity?
• Does the load direction/magnitude vary due to the deflection of the model?

If the answer is yes to any of the above then you should use the Nonlinear Analysis for your study