机械性质与行为详解.ppt

* (c)2003 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning? is a trademark used herein under license. Figure 6.43 Fiber-reinforced composites can fail by several mechanisms. (a) Due to weak bonding between the matrix and fibers, fibers can pull out of the matrix, creating voids. (b) if the individual layers of the matrix are poorly bonded, the matrix may delaminate, creating voids 纤维增强复合材料可以通过数种机制失效。 (a) 因为基体与纤维之间较弱的结合，纤维能从基体中拔出并产生产空洞。 (b) 基体的各层之间结合力差，基体材料可能剥离并产生产空洞。 * Example 6.13 Fracture in Composites 复合材料断裂 Describe the difference in fracture mechanism between a boron-reinforced aluminum composite and a glass fiber-reinforced epoxy composite. 描述硼增强铝复合材料与玻璃纤维增强环氧树脂复合材料之间断裂机制的差别。 Example 6.13 SOLUTION In the boron-aluminum composite, the aluminum matrix is soft and ductile; thus we expect the matrix to fail in a ductile manner. Boron fibers, in contrast, fail in a brittle manner. Both glass fibers and epoxy are brittle; thus the composite as a whole should display little evidence of ductile fracture.在硼增强铝复合材料中，铝基体柔软且有延展性，因此我们预期基体失效的方式为延展性断裂，与之对比，硼纤维断裂是脆性的。玻璃纤维和环氧树脂都是脆性断裂方式，这样整个复合材料显示少许延展性断裂的迹象。 * Section 6.14 Weibull Statistics for Failure Strength Analysis 韦布尔统计用于断裂强度分析  Weibull distribution - A mathematical distribution showing the probability of failure or survival of a material as a function of the stress. 韦布尔分布 – 表示材料失效或有效随应力变化的概率分布。 * (c)2003 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning? is a trademark used herein under license. Figure 6.44 The Weibull distribution describes the fraction of the samples that fail at any given applied stress. 描述在任意给定应力下失效样品分数的韦布尔分布 * Example 6.14 钢和氧化铝陶瓷的韦布尔模数Weibull Modulus for Steel and Alumina Ceramics Figure 6.45 shows the log-log plots of the probability of failure and strength of a 0.2% plain carbon steel, an alumina ceramics prepared using conventional powder processing in which alumina powders are compacted in a press and sintered into a dense mass