Tuesday  |  Frick  |  09:20 AM–09:40 AM

#13286, Error Reduction in Contour Method Residual Stress Measurements by Minimizing Deformations During Cutting: Comparing Fixture Designs

Accurate residual stress measurements via the contour method rely on the assumption that the cut is constant width relative to the part before it deforms. The “bulge” error occurs when stresses are relieved during cutting and the material at the cut tip deforms prior to it being cut, thus changing the relative cut width. This error can be reduced by securely fixturing the part to minimize deformations during cutting. In this work, a quantitative comparison between different fixture methods is conducted with Abaqus finite element simulations using cut tip deformation as a metric, and one such fixture method is experimentally tested by performing contour method measurements on 7050 aluminum. It is revealed that controlling deformations during the cut is more difficult than originally thought, with several fixture designs performing only marginally better than the widely used finger clamp fixture. The self-restraint method was found to perform the best for reducing bulge error, and a variation of this method that does not require drilling a hole in the cut path is presented and compared. The issue of experimentally confirming these conclusions was also studied since the simulations rely on idealized boundary conditions. Deformation at the cut tip would be challenging to measure during a cut, but other measurable quantities such as the cut mouth displacement are highly correlated with the cut tip deformations.

Joshua Dyer   Los Alamos National Laboratory
Michael Prime   Los Alamos National Laboratory
Marshall Maez, Jr.   Los Alamos National Laboratory