## General Mechanical

#### Simulation of human foot on shoe

• A L
Subscriber

Hello to all,

I am trying to run a simulation of a human foot model on a shoe midsole constructed out of a lattice diamond structure.

This is the setup of the model and the generated mesh.

I have set the boundary conditions are seen below:

300N acting downwards on the flat surface of the foot (based on 60kg weight acting on 2 feet)

The bottom of the midsole has been set as a fixed support.

The contact between the bottom of the foot and the top of the midsole has been set up as frictional contact, with the bottom of the foot being the contact and the top of the midsole being the target.

I am trying to study the deformation/compression of the midsole when the force is applied via the foot, as well as obtain the plantar pressure map of the foot. However, I am unable to achieve a reasonable result.Even with the weak springs option turned on, I am unable to achieve a solution due to the following error: An internal solution magnitude limit was exceeded. Please check your Environment for inappropriate load values or insufficient supports.  Please see the Troubleshooting section of the Help System for more information."

Would greatly appreciate any advice on this, thank you!

• A L
Subscriber

To add on, the materials have been set to consider the foot as a bony structure with Young's Modulus of 7.3GPa and Poisson Ratio of 0.3 (Isotropic Elsaticity) and the midsole to have a Young's Modulus of 1.2MPa and Poisson Ratio of 0.48 (Isotropic Elasticity). In theory, since the foot has a higher Young's Modulus value, it should cause the shoe sole to compress while suffering from minor deformation. However, some of the varied results I have obtained so far includes the midsole experiencing 0 total deformation while the foot experiences an abnormally high value for deformation, as seen in the picture below. For reference, the midsole thickness is merely 25mm.

• Erik Kostson
Ansys Employee

Hi

It is better to use a displacement instead of force (Y=disp, X=0, and Z=0), and then look at the reaction force of that displacement – in that way the model is properly constrained (with a force it is not – free to slide in X and Z). ALso use the contact tool to see that the contacts are active and OK.

All the best

Erik