Mobile Torsion Test – Non-Destructive Testing of Material Properties
Keywords: Non-destructive material testing, handheld device, sheet metal
When performing mechanical strength testing on semi-finished sheet metal and sheet metal products, a sample must generally be cut out and then tested on a testing machine. However, this destructive sampling is not always possible and is usually undesirable. Known, quasi-non-destructive testing methods, such as mobile hardness measurement, cannot be readily and accurately converted into a strength value in the form of the yield strength. The new handheld device for conducting torsion tests allows the yield strength of flat and slightly curved components to be tested without taking a sample. In this process, the test specimen is clamped on both sides and twisted in the sheet metal plane by two punches in opposite directions. The material’s resistance to twisting is measured as torque. Through appropriate analysis, conclusions can be drawn regarding the material’s strength.
Advantages
- Non-destructive testing
- Mobile system
- Measurement of large components
- Measurement possible during operation
Commercial Applications
The method has a wide range of applications, including the quality inspection of aluminum and steel sheets, particularly when testing the local strength of components after cold forming. For large-area components, multiple measurements allow for inspection of the entire component. The system’s portability also makes it possible, for the first time, to inspect components and tools while they are in operation.
Current Status
A German patent application for the invention was filed in 2015. The general principle of the method has been tested and is functional (see video). A prototype of the mobile system has been completed. Provendis is offering licenses for the invention to interested companies on behalf of TU Dortmund.
Relevant Publications
Institute of Forming Technology and Lightweight Components, IUL. “In-Plane Torsion Test.” 2018. URL: https://youtu.be/1vuT8gBvM0Y
Traphöner, H., Clausmeyer, T., Tekkaya, A. E.: “Material characterization for plane and curved sheets using the in-plane torsion test – An overview” in J. of Materials Processing Technology, Vol. 257, 2018, pp. 278–287.
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An invention by the IUL at TU Dortmund