Automatic element conversion for surface contact

These tests verify the automatic element conversion feature of Abaqus. With this feature if a quadratic element is specified as part of a secondary surface definition and there is no midface node on the contacting face, Abaqus automatically generates a midface node and modifies the element definition appropriately. Temperatures and predefined field variables at the automatically generated nodes are determined by interpolation from the existing, user-defined nodes. The conversion of C3D20, C3D15, and S8R5 elements into C3D27, C3D15V, and S9R5 elements is tested for the case of contact between a deformable body and a rigid surface, as well as contact between two deformable bodies.

In the first test a uniform temperature change of 50° is first applied to all of the elements to verify the temperature interpolation of the automatic conversion procedure. The elements then undergo uniform compression via contact with a frictionless rigid surface. The solution is compared to an identical model composed of C3D27, C3D15V, and S9R5 elements defined explicitly in the input file (no conversion is necessary). The second and third tests verify contact between pairs of deformable bodies in which the elements of the secondary surface undergo automatic conversion.

In all three cases the material is assumed elastic with Young's modulus of 3 × 10⁶ lb/in², Poisson's ratio of 0.3, and a thermal expansion coefficient of 1 × 10⁻⁶.