I am continuing to work on a biphasic, pressurized cavity problem with the Ogden material. The spherical geometry consists of two hollow spherical subregions with biphasic contacts to enable local refinement in mesh density. The simulations I have been working on lately have terminated early due to a negative Jacobian.
Repeated runs of this simulation on the PC (with exactly the same input file) consistently yielded the same failure in the same element and time step. However, repeated runs of this simulation on OS X (again, with exactly the same input file) yielded a negative Jacobian in different elements at different time steps (and different from the element and time step on the PC). All failures occurred in elements along the x-axis on the inner subregion, though the particular element varied from run to run. Attached are the feb file and three log files from various runs of the simulation (one on the PC and two on OS X).
In practice, I have done this simulation on a model similar to the one attached but with three subregions and a higher mesh density. In those simulations, the failures occurred more randomly, in both the innermost and outermost subregions and not always along edges or surfaces. The failures in the outer subregion typically occurred in elements that had not deformed significantly from their unloaded state.
As an aside, the problem usually does not occur at all when the Ogden material is replaced with an isotropic elastic material definition.
Can anyone help to solve this problem?
Thanks,
Joel
Repeated runs of this simulation on the PC (with exactly the same input file) consistently yielded the same failure in the same element and time step. However, repeated runs of this simulation on OS X (again, with exactly the same input file) yielded a negative Jacobian in different elements at different time steps (and different from the element and time step on the PC). All failures occurred in elements along the x-axis on the inner subregion, though the particular element varied from run to run. Attached are the feb file and three log files from various runs of the simulation (one on the PC and two on OS X).
In practice, I have done this simulation on a model similar to the one attached but with three subregions and a higher mesh density. In those simulations, the failures occurred more randomly, in both the innermost and outermost subregions and not always along edges or surfaces. The failures in the outer subregion typically occurred in elements that had not deformed significantly from their unloaded state.
As an aside, the problem usually does not occur at all when the Ogden material is replaced with an isotropic elastic material definition.
Can anyone help to solve this problem?
Thanks,
Joel
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