METHOD OF LIFETIME PREDICTION FOR SAILPLANE FIBRE STRUCTURES

Authors

  • Christoph Kensche Presented at the XXV OSTIV Congress 1997, Saint Auban, sur Durance, France.

Keywords:

Structures, Materials, Design, Maintenance

Abstract

A method of lifetime prediction for sailplane structures made from glass fibre reinfoced plastics (GFRP) is presented. The procedure is based on the application of the linear  Palmgren-Miner rule, constant amplitude life diagrams which are derived from s-n curves for glass epoxy (GI-Ep) and unsaturated glass polyester (GI-UP) respectively, and the wind energy-specific WISPER-load sequence. The resulting prediction is compared with load spectra tests on the same specimens as used for the s-n curves. The accuracy is satisfactory. However, the conformity of the test results and the prediction also depends on the scatter of the tests and the applied survivability (here 95%). The applications of safety factors and the influence of stress concentrations in load introduction parts of wing structures are discussed.

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