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本文应用扫描电镜摄获了存留在聚丙烯厚试件断口上的银纹——裂纹形态。由于银纹是由拉应力作用产生的,所以一般最大主应力σ_1造成的断面上很难观察到。银纹是高分子材料的一种准断裂行为。银纹研究的文献报导不少,Kambour作了大量工作。然而,绝大多数文献是对薄膜和薄板进行研究的,研究断口银纹工作的报导很少。本文观察研究了聚丙烯弯曲断品银纹。从材料力学得知,当试件承受弯矩作用时,中性面的一侧沿纵轴方向受拉应力σ_1的作用,另两个主应力σ_2和σ_3位于横截面上。本文拍摄的银纹——裂纹形态就是由σ_2的作用造成的。
In this paper, the scanning electron microscopy of the specimen retained in the polypropylene thick specimen fracture - crack morphology. Since the silver grain is produced by the tensile stress, it is difficult to observe the cross section caused by the general maximum principal stress σ_1. Silver grain is a quasi-fracture behavior of polymer materials. There have been a lot of reports on the research of silver pattern, and Kambour has done a lot of work. However, most of the literature is on the thin film and sheet research, the study of the work of the fracture silver stripes rarely reported. In this paper, we observed the silver bending of polypropylene product. From the material mechanics, when the specimen under bending moment, one side of the neutral plane is affected by the tensile stress σ_1 in the direction of the longitudinal axis, and the other two principal stresses σ_2 and σ_3 are located in the cross section. This paper shot the silver grain - crack shape is caused by the role of σ_2.