When it comes to metal or plastic damage, BIQUAD is a widely used, efficient and userfriendly failure model. This criteria is available in OptiStuct for Explicit Analysis since version 2023. This failure model uses a simplified stress triaxiality & plastic strain-based, failure criteria with linear damage accumulation. The failure plastic strain is described by two parabolic functions calculated using curve fitting from up to 5 user-defined failure strains. 

The aim of this knowledge base article is to share an excel speadsheet that will allow users to visualize the failure limits according to their setup. The parameter default values and the stress softening parameters are in compliance with the 2023 version of OptiStruct. Each parameter is explained with comments in the Excel spreadsheet. 

This Excel spreadsheet was built by Valentin Davaze & Mathis Loverini.