Section controls are available for solid, shell, and continuum shell elements in an Explicit Dynamics case. They allow you to modify the element formulation to suit the conditions of an analysis. You can modify the following when you edit the global or local element assignments:

• Distortion control

• Hourglass control

• Second-order accuracy

The controls and options available depend on the selected element type. Section controls are advanced options; in most cases you should use the default values. See Section controls in the Abaqus Elements Guide for more information.

Distortion control is available for solid elements. It is intended to prevent element inversion or excessive distortion, such as when crushable materials with a relatively coarse mesh are subjected to high strains. A length ratio is multiplied by the characteristic element length to determine the acceptable amount of distortion before penalty forces are applied. Distortion control is on by default for elements with hyperelastic or hyperfoam materials, and the default distortion length ratio is 0.1. For other material types, distortion control is off by default. You can activate and deactivate distortion control or change the length ratio. Use of a finer mesh can also prevent excessive element distortion.

Hourglassing is a condition that occurs when reduced-integration elements, whose element formulation offers no resistance to bending, are subjected to pure bending moments. Hourglassing can lead to severe mesh distortion, especially where there are few elements through a section. Hourglass control adds stiffness to resist bending while attempting to retain the desired element response to other loads. An integral viscoelastic approach for hourglass control is applied by default. You can choose from several other approaches to hourglass control. See Methods for suppressing hourglass modes in Section controls in the Abaqus Elements Guide for more information. Use of a finer mesh in thin sections can also reduce hourglassing.

First- and second-order accuracy formulations are available for solid and shell elements in an Explicit Dynamics case. First-order accuracy is the default and is suitable for most analyses due to the small time increments used by Abaqus/Explicit. Second-order accuracy should be used if components of a model are revolving more than five times during an analysis.

To apply section controls to a model, see Modifying Global Element Assignments, or Modifying Local Element Assignments.