LS-DYNA Analysis for Structural Mechanics Workshop II: Hourglass Control

This is the second Workshop in our FEA training course: LS-DYNA Analysis for Structural Mechanics. This course is geared toward the engineering professional simulating highly nonlinear, transient dynamic problems involving large deformations and contact between multiple bodies. A script of the Workshop is as follows: Isoparametric Shell/Solid Elements and Hourglassing* • All under-integrated isoparametric elements (one Guass point) have hourglassing present. It is a non-physical “zero-energy” mode of deformation. • Fully Integrated formulations do not hourglass. Additionally, tetrahedron and triangular elements do not hourglass but are overly stiff in many applications. • *Control_Hourglass or *Hourglass to set hourglass control. • Use default unless additional documentation is consulted (e.g., see Review of Solid Element Formulations Erhart.pdf (Class Reference Notes / Solid Elements). • Hourglass energy should be less than 10% of the internal energy at any stage of the analysis (use *CONTROL_ENERGY (HGEN=2) to calculate hourglass energy). • In LSPP, check glstat for total hourglass energy and then matsum for individual part energy.