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Stiffness with loss of material

Submitted by vishnusworld on

Dear All

I am modeling a workpiece supported in fixtures and being machined. I use the FEM ( Ansys) to simulate this set up. I need to know at the stiffness of wp at the wp-fixture contact point  . Stiffness is found by applying unit force at one contact point while fixing all others.. Inverse of displaceemnt gives the stiffness in that direction. I have two questions reg this.

1. I can use the element death technique to model the material removed for each cut. Let the original material be of 100 mm height and 20 mm is removed in 4 strokes ( 5 mm in each stroke of the cutter). Let the stiffness be 'k' units after this removal. Now if a take a virgin wp of height 100-20= 80 mm, will the stiffness be the same 'k' or different?

2. As the material is removed the stiffness seems to go up, albeit not much different..Any explanation for this behaviour?

Thanks.