Paper number 1093

TOWARD AN ACCURATE FAILURE CRITERION OF ANISOTROPIC MATERIALS, A NEW FLEXURE TEST CONSIDERING THE COUPLING EFFECT

Raed Rachdan, Masaru Zako, Naoki Takano, and Daisuke Nishida

Professor Zako Laboratory, Department of Manufacturing Science
Faculty of Engineering, Osaka University
2-1 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan

Summary

This work aims to propose a new simple test procedure that aims to give an accurate evaluation of the strength of an off-axis unidirectional lamina. After obtaining positive results from a 3D finite element analysis investigating the stress state due to the coupling effect in off-axis unidirectional specimens under bending loads, we could prove the utility of designing and using a test machine that allows specimens to twist as well as flex while deforming under these loads. Furthermore, this analysis has proven that the specimen bending stress at failure could be computed with a good approximation by using the simple beam theory. Consequently, the In-plane stress state in the specimen could be defined. And the failure envelope in sigma12-sigma22 domain, and a 3D representation, in the space defined by the axes sigma11, sigma12 and sigma22 were plotted. This failure envelope has good potential to be used as a failure criterion to evaluate the lamina cracking resistance.

Keywords

off-axis specimen, flexure test, coupling effect, finite element stress analysis, ply strength, failure criterion.