Investigation On The Bending Properties And Shearing Properties Of2-D Triaxial Braid Laminated Composites With And Without Open-holes

In the practical application of composite materials, mechanical connection is one of the mostcommon methods when composite parts connected to other components. The mechanicalconnection requires opening, however the openings will directly affect the performance of thecomposite parts. Therefore more in-depth studies are needed to understand mechanicalperformance and failure mode of specimens which use mechanical ways open holes. The bendingproperties and shear properties are most important parameters for composites, but most studiesfocused on the mechanical properties and failure mode of laminates composites. However, fewstudies studied bending properties and shear properties of2-D triaxial braid laminated compositeswith different layers, with and without open-holes.The study of this paper mainly contains:1.2-D triaxial braid laminated composites withdifferent layers use ordinary mechanical ways to open holes and then use Microscope to observedamages in hole.2. Having bend and shear tests before and after opening holes of2-D triaxialbraid laminated composites with different layers and getting relations of bend property and shearproperty between2-D triaxial braid laminated composites with different layers, with and withoutopen-holes.3. Investigated influence of the hole on the bending and shear properties of materialand observed the cracks on the section and surface of composites to analyze the failure mode. Theratio of specimen width to diameter of the hole is3.88.The result showed by bending and shear tests as follows:1. The comparison in bending properties of2-D triaxial braid laminated composites with andwithout holes: The maximum bending load and bending strength of2-D triaxial braid laminatedcomposites dropped by a third and their bending elastic modulus dropped by a half, when2-Dtriaxial braid laminated composites with open-holes compared with2-D triaxial braid laminatedcomposites. No matter with or without holes, the maximum bending load and bending elasticmodulus increased with the increasing of layers, but when the layers reach a certain number, the change in the bending performance dropped. When bending load was applied, the main failuremode was compression failure. The influence area of open-holes was within1～2mm from theedge of the hole.2. The comparison in shear properties of2-D triaxial braid laminated composites with andwithout holes: The failure load and shearing strength of one layer2-D triaxial braid laminatedcomposites dropped by a half. The failure load and shearing strength of2-D triaxial braidlaminated composites with two and three layers dropped by a forth. No matter with or withoutholes, the failure load increased with the increasing of layers, when shear load was applied, themain failure mode was inner shear failure. The influence area of open-holes was within1～2mmfrom the edge of the hole.3. When bending and shear load was applied, interlayer stratification occurred in2-D triaxialbraid laminated composites. In order to avoid the occurrence of delamination between layers, weshould use2-D triaxial braid laminated composites with odd layers.Results of this paper provide a reference to design and engineering applications of2-Dtriaxial braid laminated composites.