SYMPOSIA PAPER Published: 01 January 1989

Checking and Improvement of the Alignment of Flat Specimen Gripping Devices


The reliability of results of fatigue tests depends to a high degree on the accuracy of the alignment of the gripping devices used. Misalignments can result in undesired additional stresses and strains in the specimen under test and can lead to inaccurate test results. A method is presented by means of which the alignment of flat specimen grips can be checked and steps for its improvement derived using a specific set of strains, which are measured at eight selected points of a dummy specimen clamped in its four possible gripping positions. The mathematical description of the strains in the clamped specimen, including those caused by a productional precurvature, leads to an analysis of the measured strains by means of an evaluation scheme which is derived from the obtained mathematical equations and tailor-made for the use of a computer. The results of the analysis allow judgment as to the accuracy of the alignment and the derivation of steps for its improvement.

Author Information

Fischer, R
Carl Schenck AG, Darmstadt, West Germany
Haibach, E
Seilpruefstelle der WBK, Bochum, West Germany
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Developed by Committee: E28
Pages: 136–159
DOI: 10.1520/STP24018S
ISBN-EB: 978-0-8031-5086-7
ISBN-13: 978-0-8031-1251-3