Assessment of Error of the Experimental Determination of Interlaminar Shear Strength

Abstract

AbstractOwing to high strength and weight perfection of the polymeric composite materials, they are used in the manufacturing of various equipment. Laminated polymeric materials are the most studied and widespread composite varieties. These materials implement high elastic and strength characteristics in the reinforcement plane; however, they have minimal performance capabilities at interlaminar shear. Assessment of non-uniform distribution of shear stresses over the shear surface is carried out for the specimens intended for determination of the interlaminar strength according to the current standards. Based on the model of adhesive joint, the dependence is obtained which relates the error in assessment of the interlaminar shear strength to the elastic characteristics of the material and geometry of the specimen’s working part. The dependence allows controlling the degree of underestimation of interlaminar shear strength of the material when planning the experiment. Modification of specimens recommended by normative documents for interlaminar shear tests is substantiated. The results of experimental study of unidirectional carbon fiber composite interlaminar strength using modified specimens are presented. The typical nature of failure of specimens with 90° and 0° layup patterns after tests is analyzed. According to results of the experiments, values of interlaminar strength are at the level of 53.5 MPa, with the variation coefficient of 3.5% and 5.7% underestimation of the result.KeywordsComposite specimenNon-uniform distributionStrength reductionAdhesive joint