Determination of G(12) by means of the off-axis tension test. Part 1: review of gripping systems and correction factors

The determination of the intralaminar shear modulus G(12) in composite mate rials is by no means a straight forward task. Several different tests and p rocedures have been proposed, with the off-axis test achieving popularity a s a result of its apparent simplicity. A review of the most significant stu dies and proposals connected with the determination of G12 by means of the off-axis tension test is presented in this paper. The majority of the contr ibutions can be classified in two general approaches. The first approach co ntains the proposals to modify the gripping system in order to allow the id eal deformation of the specimen. Particular attention is paid to the use of rotating grips and the results obtained. Reasons why other authors did not achieve satisfactory results are explored. In the second approach a cohere nt correction scheme, based on an iterative procedure applied to measuremen ts obtained from the test, is presented. Finally, the dependence of the cor rection factor, based on the Pagano and Halpin analysis, upon the propertie s of the material is discussed. (C) 2001 Elsevier Science Ltd. All fights r eserved.