Learning Forum

[NPDan]

I'm a student learning Ansys currently. I am working on a project where I would like to analyze shear stress on a bolt in a bolt circle due to rotation of one of the bolted bodies. This is to simulate shear stresses on a bolt in a lathe chuck due to tangential forces.

I have worked on this model for several hours, I have had to introduce myself to contact features, cylindrical supports, bolt pretension, and shear probing.

I have a model that solves, and produces shear stress values that are reasonable (I believe) based on a simple analytical calculation for shear stress on cylindrical bodies. The equation is the general solution for average shear stress on a cylindrical body : Tau = (4 * F) / (pi * D^2).

For a force of 5000 N, and a bolt diameter of 10 mm (M10 hex cap), this equation evaluates to 63.66 MPa.

The Ansys shear stress tool is applied to a volume of elements and only captures the threaded body of the bolt. The maximum shear stress is 69.23 MPa. This is deviation is acceptable, but I have a feeling I am not modelling this entirely correctly, mainly based on the distribution produced. It is extremely uniform and only has several small points of concentration.

I am modelling a sixth of the entire assembly, with frictionless supports on the spindle (bottom body) on both sides of the 60 degree section, and 1 frictionless support on the bottom. I have applied a cylindrical coordinate system with the tangential direction set to free for the top body.

[peteroznewman]

If the bolts are tensioned correctly, the friction between the lathe chuck and the lathe mount will prevent any slip between those two parts. The bolts will see only tensile stress.