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Ansys Learning Forum › Forums › Discuss Simulation › LS Dyna › Question on what sigma Max is in spall models › Reply To: Question on what sigma Max is in spall models

October 28, 2024 at 4:05 pm
Pedram Samadian
Ansys Employee

Hi,

Thanks for contacting us. The LS-DYNA User Manual Vol II (LSDYNA Manuals) under *MAT_011 Remark 5 (spall models) clarifies that SigMax is the maximum principal stress (Cauchi) that the material experiences. 

Principal stresses are applied on a plane of the material on which no shear stress exists. To obtain the principal stresses from the global stress tensor, the stress tensor needs to be diagonalized. Details about how to calculate the prinicpal stresses can be found in the textbook entitled “Metal Forming” by Hosford and Caddel (W.F. Hosford and R.M. Caddell, Metal forming: Mechanics and Metallurgy, 3rd ed., Cambridge University Press, Cambridge, 2007).

Thank you,

Pedram