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Showing posts from February, 2018

U* Index for Load Path Analysis

An XANSYS forum poster pointed out an interesting thesis on load path index U*. There was a brute force method of a solution for every single node shown in Figure 8. Alternately, there is a  U* Toolkit  found in Nastran which appears to really speed the calculations. The brute force method was used here in this Ansys Classic input file :  link Figure 1: Load Path Index U*

Torsional Spring in ANSYS Workbench

Torsional springs can come in handy when inertia plays a large role in the dynamic response. Fortunately a simple snippet converts a typical linear spring into a torsional spring. Workbench uses COMBIN14 springs by default. keyopt , _sid, 3, 1    ! rotational DOF about spring axis r , _sid, 0.01        ! rotational stiffness Torsional Mode due to Torsional Spring One could also specify the radial stiffness of the spring above by specifying the direction. Note that KEYOPT(2)=1. keyopt , _sid, 2, 1 ! UX direction about global axis r , _sid, 1e5            ! Translation stiffness Same goes for off-axis rotational DOF via KEYOPT(2)=4. keyopt , _sid, 2, 4 ! ROTX direction about global axis r , _sid, 1e5            ! Rotation stiffness The Workbench (v18.2) Archived File: LINK