Nonlinear Finite Element Analysis

It is often said that “nature is nonlinear”!  Some common everyday situations illustrate important types of nonlinear behavior:  flexing a paper clip CV-Boot_Stressback and forth; stretching a rubber band to many times its original length; crushing a beer can so that it buckles; and pressing a finger against a balloon to form a dimple. The three major types of structural nonlinearities are:

  • Geometric Nonlinearity (large deformation, large strain, snap-through buckling)
  • Material Nonlinearity (plasticity, creep, viscoelasticity, rubber & elastomeric materials)
  • Boundary Nonlinearity (contact and separation between components, follower forces)

Nonlinear Finite Element Analysis can appropriately treat all of these types of nonlinearities.  In general, the complete nonlinear stiffness is comprised of three parts:

  • Elastic Stiffness
  • Initial Stress Stiffness
  • Geometric Stiffness

Nonlinear analysis is essential in many design and manufacturing problems.  Some examples include:

  • Manufacturing simulations – sheet metal forming, rolling, deep-drawing, welding
  • Assembly analysis – snap fits, press fits, mechanical connections
  • Rubber and elastomeric material analysis
  • Failure analysis – overstress, material failure, fracture, crack propagation

Most failure analysis investigations require the use of nonlinear finite element analysis.

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Click Image for Animation of Von Mises Stress during Sheet Metal Break Forming

Click Image for Animation of Von Mises Stress during Sheet Metal Break Forming