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为了研究2.5D机织复合材料的压缩损伤和失效机制,验证双尺度渐进损伤有限元数值模拟方法的有效性,对这类复合材料分别沿经纱方向和纬纱方向进行了准静态压缩实验,获得了其相应的应力-应变曲线,并测定了材料的初始弹性模量和极限强度。在此基础上,利用双尺度渐进损伤有限元数值方法模拟分析了材料的压缩应力-应变响应和损伤演化行为,取得了与实验吻合较好的模拟结果。结果表明:2.5D机织复合材料在纬向压缩下的主要失效模式是纬纱的轴向压溃与断裂,可获得相对较高的压缩强度;但在经向压缩下,经纱因弯曲会承受附加弯矩作用,从而对周围基体造成挤压,故在经纱轴向断裂之前容易出现经纱之间基体的压溃和纱线之间的分层开裂,使强度降低,不利于发挥纤维的承载优势。
In order to study the compression damage and failure mechanism of 2.5D woven composites and verify the validity of the numerical simulation method for two-scale asymptotic damage, the quasi-static compression experiments of these composite materials along the warp direction and the weft direction were carried out respectively. The corresponding stress-strain curves were obtained and the initial elastic modulus and ultimate strength of the material were determined. On this basis, the compressive stress-strain response and damage evolution behavior of the material were simulated and analyzed by using two-scale asymptotic damage finite element method. The simulation results agreeing well with the experimental results were obtained. The results show that the main failure mode of 2.5D woven composites under weft compression is the axial crushing and breaking of weft yarns, and the relatively high compressive strength can be obtained. However, under the warp compression, Bending moment, and thus the surrounding matrix caused by extrusion, it is easy to appear in the warp yarn rupture before the collapse of the substrate between the matrix and the yarn stratified delamination, so that the strength is reduced, is not conducive to play a fiber bearing advantages.