Hi, I created a simple linear FEA model of bone screw construct to find out the torque (moment reaction) using Ansys workbench 15 as follows:
http://postimg.com/170000/screen-shot-2014-10-17-at-114025-am-169696.jpg
Here, the screw is rotated anticlockwise about x-axis into the bone. The screw thread cant go further down the bone during rotation. This is done to simulate the screw head contact with the bone. So, i am trying to find torque (moment reaction) during tightening of screw into bone to findout the maximum torque just before bone failure. I have carried out the rotation of screw head by remote displacement method and got the moment reaction forces. But, it didnt give me the result as quite expected. Here's the result of moment reaction forces:
http://www.postimg.com/170000/moment-reaction-169702.jpg
The image shows that the moment reaction forces is more in z direction. The moment reaction forces should be maximum in x direction (along which screw was rotated).
Did i miss anything in calculating moment reaction ?
This solution is static, you get behavior of contact as it would be in case of applied force to screw.
In order to get reaction of screwing directly, I think there no way. My proposal - get normal forces from contact and calculate sliding friction by contact reactions this requires some extra programing or analytic calculation as whole screw.
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