*By Amy Castor* (for SolidWorks newsletter)

While most engineers are familiar with linear analysis, nonlinear still gives some the jitters. Many think it requires complex solvers and skilled expertise. But those requirements are in the past. Today COSMOS, a suite of analysis software that seamlessly integrates with SolidWorks design software, makes it easy to perform nonlinear analysis directly on your The trick is in knowing when you need nonlinear analysis, and when you don’t.

Linear analysis, as the name implies, assumes a simple linear relationship between force and deflection. Twice the load makes the object bend twice as much. Linear analysis also assumes an object is perfectly elastic, so that once you remove the load, the object returns to its original shape.

But in reality, nature is nonlinear. Anytime you apply force to an object, the object takes on some measure of permanent deformation as a result. You can see examples of this in everyday life. If you push on one end of a paper clip, the paper clip stays bent. When someone stands on the end of a diving board, the tip of the board dips at an angle.

How much an object deforms depends on a material property called “stiffness.” Linear analysis assumes a constant stiffness, but in the real world, loads, stresses, and strains change the stiffness of an object and, therefore, affect how the object behaves.