Re: wrong displacement values using "ElasticSolver"?
Posted: 25 May 2024, 12:12
"With this definition we say that the Young's modulus is constant, regardless of stress and strains. Is this correct?
Are you saying that the ElasticSolver decides by its own that beyond a certain strain the material is no longer linear?
Moreover, beyond the yield strength, in typical materials the Young's modulus decreases, whereas according to the ElasticSolver solution the Young's modulus increases at higher strain!"
ElasticSolver is geomterically non-linear solver, it does not have material non-linear built in. In geometric non-linear the young's modulus is constant, there is no yielding but at high displacements the structure stiffens in tension as you try to pull it farther and farther, in compression it may stiffen or buckle, in bending it typically gets stiffer. These geometric non-linears are not related to material or yielding. For example I ran
0.1x0.01x1.0 square shape fixed at 1 end pull on the other. E=5.E6, F= 5.E5, the linear displacement is 0.01, but using the geometric non-linear solver the displacement is 0.088, a high Poisson ratio will reduce it to 0.081. However if I change E to 5.E11 then both the linear and geometric non-linear solvers produce 1.E6.
Your problem, as defined, is geometrically non-linear, it will stiffen the more you stretch it if you use the geometric non-linear solver.
Are you saying that the ElasticSolver decides by its own that beyond a certain strain the material is no longer linear?
Moreover, beyond the yield strength, in typical materials the Young's modulus decreases, whereas according to the ElasticSolver solution the Young's modulus increases at higher strain!"
ElasticSolver is geomterically non-linear solver, it does not have material non-linear built in. In geometric non-linear the young's modulus is constant, there is no yielding but at high displacements the structure stiffens in tension as you try to pull it farther and farther, in compression it may stiffen or buckle, in bending it typically gets stiffer. These geometric non-linears are not related to material or yielding. For example I ran
0.1x0.01x1.0 square shape fixed at 1 end pull on the other. E=5.E6, F= 5.E5, the linear displacement is 0.01, but using the geometric non-linear solver the displacement is 0.088, a high Poisson ratio will reduce it to 0.081. However if I change E to 5.E11 then both the linear and geometric non-linear solvers produce 1.E6.
Your problem, as defined, is geometrically non-linear, it will stiffen the more you stretch it if you use the geometric non-linear solver.