I am running VABS via preVABS and I had a question regarding the reported values for "Failure Index" when the tsai-hill failure criteria is specified. I've gotten tripped up in the past due to Abaqus and Nastran reporting different values for the tsai-hill failure index. I was hoping to get confirmation, in preVABS/VABS, is the reported tsai-hill failure index calculated using the first formula or the second formula?
What you listed only works for plane-stress. What uses in VABS is for 3D stresses. Please see attached.
For 3D stresses, we output failure index the same as your FI#1 for plane-stress. The strength ratio is the 1/FI#2 for plane-stress.
Please let us know you other questions. Please also try iVABS (https://wenbinyugroup.github.io/ivabs/), many scripts you need to write yourself are also available in that package.
Dana Frye @ on
Hello,
I am running VABS via preVABS and I had a question regarding the reported values for "Failure Index" when the tsai-hill failure criteria is specified. I've gotten tripped up in the past due to Abaqus and Nastran reporting different values for the tsai-hill failure index. I was hoping to get confirmation, in preVABS/VABS, is the reported tsai-hill failure index calculated using the first formula or the second formula?
FI #1: σ112 / X2 - σ11*σ22 / X2 + σ222 / Y2 + σ122 / S2
or
FI #2: sqrt(σ112 / X2 - σ11*σ22 / X2 + σ222 / Y2 + σ122 / S2)
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Wenbin Yu @ on
What you listed only works for plane-stress. What uses in VABS is for 3D stresses. Please see attached.
For 3D stresses, we output failure index the same as your FI#1 for plane-stress. The strength ratio is the 1/FI#2 for plane-stress.
Please let us know you other questions. Please also try iVABS (https://wenbinyugroup.github.io/ivabs/), many scripts you need to write yourself are also available in that package.
Pages-from-MSG-2.pdf
236 KBClick to download
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Dana Frye @ on
Thank you!
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