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finite element methods

Producing Stress Analysis from Strain data

Submitted by G Rezk on
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finite element methods
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I am doing research on the stresses that are produced when a retainer (a thermoplastic sheet) is placed on the teeth. We've designed the project so that we take an initial scan of the sheet and a final "shifted" scan of the sheet. We'd like to compare, find the strain, and calculate the stress neccessary to produce this strain.

I was hoping to use FEA for this...is it possible? I have access to Abaqus and Ansys, and where can i find the commands that allow me to do this.

Energy conservation in nonlinear finite element explicit dynamics

Submitted by Robin Selinger on
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finite element methods
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I am writing to ask about the state of the art in finite element simulation using nonlinear elasticity and explicit dynamics.

Consider, for instance, a 3-d simulation of a hyperelastic beam that's fixed on one end, then  twisted about its long axis by 360 degrees and released. If we apply no friction or viscosity, the sum of kinetic plus potential energy should remain constant as the material springs back and oscillates.

Which FEM codes do the best at conserving KE+PE for a simulation of this type?  If you drop the time step, can you get energy conservation to many significant figures, as one can with, for instance, molecular dynamics simulation? 

I'm curious because I've recently written my own 3-d nonlinear explicit dynamics code that provides very high precision energy conservation, and I'm wondering if it's any better or worse than the nonlinear explicit dynamics codes already available.

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