Technical rule 2014-01
This DIN SPEC has been developed by a workshop (temporary committee) according to the PAS (Publicly Available Specification) procedure. The initiators and authors mentioned in the foreword developed and approved this document. This DIN SPEC specifies a method of using a shear test apparatus for measuring the in-plane shear stress/shear strain response, shear modulus and shear strength of continuous-fibre-reinforced plastic composite materials with fibre orientations of 0° and 0°/90°. This method is suitable for use with thermoset and thermoplastic matrix laminates made from unidirectional layers/non-woven fabrics and/or fabrics including unidirectional fabrics, with the fibres oriented at 0° and 0°/90° to the specimen axis. The lay-up shall be symmetrical and balanced about the specimen mid-plane. In this method, a test specimen is put in a state of pure shear, thus enabling testing to be carried out without interference by superimposed shear and other stresses, and, as a consequence, ensuring that the material characteristics are determined in a reproducible manner. The method is suitable for determining shear properties in both the linear and non-linear load-deformation range even at shear strains greater than 5 %. In particular, the method lends itself to determining the maximum shear strength even at shear strains > 5 %. The test specimen is gripped along all its sides by a device exerting uniform, reproducible pressure and that is equipped with a follower mechanism enabling a constant gripping force to be maintained. The test specimens have no free edges, and therefore there are no load re-distribution effects which might otherwise affect the test results. Because the maximum shear stress occurs in the central portion of the test specimen, no invalid test results owing to material failure of the specimen at the edges where it is gripped are obtained.