Effect of Heating Process on Flexural Strength and Toughness of CFRTP Molded by Multi-layer Press -Investigation on Effect of Residual Stress-
Effect of Heating Process on Flexural Strength and Toughness of CFRTP Molded by Multi-layer Press -Investigation on Effect of Residual Stress-
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DOI：
10.1088/1757-899x/859/1/012015
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
Akihito Itami;K. Obunai;K. Okubo;H. Takei
中科院分区：
文献类型：
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作者：
Akihito Itami;K. Obunai;K. Okubo;H. Takei
本研究探讨了多层压机成型时，各模具加热工艺的差异对CFRTP力学性能变化的影响。制备了10页多层成型的CFRTP试件，进行三点弯曲试验、DCB试验、ENF试验，以研究其力学性能的差异。考虑到由于各模具加热工艺的不同而产生的残余应力，研究了多层压机成型的CFRTP的力学性能变化。与第1页相比，第5页试样的弯曲强度、Ⅰ型层间断裂韧性和Ⅱ型层间断裂韧性的平均值均有所下降。假设纤维为刚性纤维，考虑到树脂的热收缩，由于树脂的自由收缩受到约束，纤维中应产生残余压应力。据认为，弯曲强度的降低与破坏接近压缩表面是由于这种额外的压缩残余应力。由于树脂自由收缩的约束，树脂中也会产生拉伸残余应力。观察到的韧性降低的树脂也发生了裂纹扩展的过程。Ⅰ型层间断裂韧性的降低幅度比Ⅱ型层间断裂韧性的降低幅度大得多。由于I型断裂是裂纹张开模式，因此树脂中的拉伸残余应力占主导地位。
This study investigated the effect of differences in heating process of each mold due to the molding with multi-layer press on changing in mechanical properties of CFRTP. CFRTP specimens molded with 10 pages multi-layer were prepared for 3 point bending tests and DCB tests, ENF tests in order to investigate the different of mechanical properties. The change in the mechanical properties of CFRTP molded by multi-layer press were investigated considering residual stress occurred by differences in heating process of each mold. Average of flexural strength, mode-I interlaminar fracture toughness and mode-II interlaminar fracture toughness of the specimen molded at 5th page were decreased compared with that of 1st page. Assuming the fiber as a rigid and considering the thermal shrinkage of resin, compressive residual stress should be occurred in the fiber since free shrinkage of the resin was constrained. It was considered that the reduction of flexural strength with the failure close to the compression surface was caused due to this additional compressive residual stress. The tensile residual stress also should be occurred in the resin due to constraint of free shrinkage of the resin. The observed reduction of toughness in the resin was also occurred for the procedure of crack propagation. The reduction rate of mode-I interlaminar fracture toughness was much remarkable than that of mode-II interlaminar fracture toughness. Tensile residual stress in the resin was dominant since the mode-I fracture is a crack opening mode.