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 materials is by no means a straight forward task. Several different tests and procedures have been proposed, with the off-axis test achieving popularity as a result of its apparent simplicity. A review of the most significant studies 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 contributions can be classified in two general approaches. The first approach contains the proposals to modify the gripping system in order to allow the ideal 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 coherent correction scheme, based on an iterative procedure applied to measurements obtained from the test, is presented. Finally, the dependence of the correction factor, based on the Pagano and Halpin analysis, upon the properties of the material is discussed. (C) 2001 Elsevier Science Ltd. All fights reserved.