OS-E: 0150 Large Displacement Analysis of Chassis

Demonstrates the use of 2D plate (shell) elements with large displacement analysis.

Figure 1. FE Model

Model Files

Before you begin, copy the file(s) used in this example to your working directory.

Model Description

This example is of a chassis modeled with shell elements and solves for large displacement analysis with the load steps:
  • Front torsional stiffness
  • Rear torsional stiffness
  • Vertical bending stiffness

Rail and Cross members modeled with shell elements, 7 are connected via rigid elements.

Displacements (translations and rotations), which are large enough to render small deformation theory invalid; therefore, the initial stiffness matrix is not suitable to represent the problem. This may result in either small or large (finite) strains. Large displacements are those that are greater than the characteristic dimension of the model (thickness of the beam plate or shell). This is always a nonlinear problem. A typical rule of thumb, if strains exceed 5%, always switch LGDISP=1.

Large deformations (geometric nonlinearity) the stiffness matrix is updated after each loading increment. If you switch LGDISP=1, then the recent stiffness that is taken to the next increment is already updated. Therefore, by having this on, the deformed geometry or an updated stiffness matrix will be taken into the next step.
FE Model
Element Types
The linear material properties are:
Young’s Modulus
2.1E5 MPa
Poisson's Ratio


Figure 2. Stress Contour and Plastic Strain Plot