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Question on what sigma Max is in spall models

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    • October 25, 2024 at 5:32 pm
      patStokes
      Subscriber

      Hello,

      For some hydro material models like MAT_011 or MAT_015 you can assign a spall value based on either pressure or sigmaMax. I am unsure of what sigmaMax is. Is this the Cauchy stress, deviatoric stress or something completely different?

    • 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

       

       

       

       

       

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