Nonlinear solver computes deformation based on force loads
Posted: 04 Jun 2021, 02:57
Hi, the great Elmer team.
I'm using Elmer to generate datasets for an elastomer deformation project. The elastomer is a thin cylinder (2cm rad with 0.3cm height). The top and lateral surfaces are fixed as our real-world setting, solid objects will contact the bottom surface and deform the elastomer. It seems explicitly simulate two objects' contact can be time-consuming, I decide to apply nodal forces among the bottom surface to imitate the contact.
To do so, I select a cluster of nodes on the bottom surface and apply force loads on each of them. The force's direction and magnitude are determined based on the solid object's geometry. Specifically, I assume the elastomer's surface aligns well with the solid object, and thus contact force's direction is the solid object's surface normal direction. The magnitude for each contact force is then determined based on normal angles.
However, the simulation results seem weird. The results seem unsmooth and wrong. The image shows the FEM results using a ball indentor and 20N contact force at max. The deformation doesn't seem to be correct. When I increase the contact force, the results crash (surface penetrate the mesh). I'm wondering how can I make this work? Is the contact formulation correct and am I applying nodal forces in the right way? I attached the sif file below FYI.
Many thanks if you could provide any suggestions
I'm using Elmer to generate datasets for an elastomer deformation project. The elastomer is a thin cylinder (2cm rad with 0.3cm height). The top and lateral surfaces are fixed as our real-world setting, solid objects will contact the bottom surface and deform the elastomer. It seems explicitly simulate two objects' contact can be time-consuming, I decide to apply nodal forces among the bottom surface to imitate the contact.
To do so, I select a cluster of nodes on the bottom surface and apply force loads on each of them. The force's direction and magnitude are determined based on the solid object's geometry. Specifically, I assume the elastomer's surface aligns well with the solid object, and thus contact force's direction is the solid object's surface normal direction. The magnitude for each contact force is then determined based on normal angles.
However, the simulation results seem weird. The results seem unsmooth and wrong. The image shows the FEM results using a ball indentor and 20N contact force at max. The deformation doesn't seem to be correct. When I increase the contact force, the results crash (surface penetrate the mesh). I'm wondering how can I make this work? Is the contact formulation correct and am I applying nodal forces in the right way? I attached the sif file below FYI.
Many thanks if you could provide any suggestions