I have read the following comment on a design code:
“Care should be taken when selecting formulations and integration rules. Formulations with (selective) reduced integration rules are less prone to locking effects than full integrated simple elements; however, the reduced integration elements may produce zero energy modes (“hourglassing”) and require hourglass control. When hourglass control is used, the hourglass energy should be monitored and shown to be small compared to the internal energy of the system (typically less than 5%).”
In the manual I can read hourglass control is automatically activated for reduced integration.
¿How could I measure that hourglass energy in CalculiX?