# Summation point handling for reaction moment

**2**

**Context**: We're struggling with extraction of reaction moments from Ansys mechanical. The biggest problem on our end is the fact that summation point is not following the center of a bolt (I want to extract bending moment for all bolts and all load cases for a given bolted joint). Usually in our models we have 60-100 explicitly modeled bolts and 10-30 load cases, This sound like a Automation opportunity. Our bolted joint can experience large deformation/rotation due to global deformation. It also has to be able to handle elevated temperatures. Currently bulletproof method (assuming quite fine mesh on bolts' shanks) for that is to calculate bending moment based on S1 stress collected from a ring of nodes around the circumference of the shank in one particular position (position where we want to know bending moment). It works, but it's not great, because end result is mesh dependent.

Ansys doesn't provide any way of updating summation point based on global position of a component/named selection/contact/etc. Let's simplify this problem to this question:

1. **How, using DPF/ACT/ironpython/Cpython can we track centroid of a contact under bolt's head for all loadsteps?**

2. **What might be the most effective way of doing it?** (as I said, I can have more than 100 bolts, with sometimes more than 30 Loadsteps and I need extract bending moment for all of the bolts at every loadstep)

Any ideas? Please talk in simple terms I'm not really proficient with DPF, but I do a lot of scripting in IronPython in Mechanical.