复合V型切口脆性断裂的分析-机械设计及理论专业论文.docxVIP

上海海洋大 上海海洋大学硕士论文 I II 最后，为了检验本文建立的双剪应力准则和体积能密度准则的准确性，采用 脆性材料有机玻璃（PMMA）脆性板材进行拉伸破坏试验。一方面，对有机玻璃 的力学常量进行了测量，如有机玻璃弹性模量、泊松比、断裂韧度等。另一方面， 将有机玻璃板材加工成 V 形切口试件，在电子万能试验机上进行拉伸破坏实验。 最后把实验测量的临界应力、开裂角与理论预测结果相比较，发现两者很好吻合， 这表明本文提出的双剪应力准则和体积能密度准则是有效的。 关键词：V形切口，实验验证，脆性断裂准则，双剪应力准则，体积能密度准 则 I III The Criterion For V-notched Brittle Fracture Under Mixed-modes Abstract In marine equipment components and all kinds of engineering machinery, V shaped incision is widespread, such as root, stepped shaft, gear steps and tool withdrawal groove etc. As the notch tip stress concentration or singular, it is easy to cause fracture and cause the accident. At present, the problem of V notches of Ⅰin both theory and experiment conducted the full research and established a fracture criterion of mature. However, the study of composite V incision member brittle fracture criterion is relatively less. Therefore, it is important for the theory significance and engineering value fracture criterion to establish a reasonable and practical composite V incision component. The main works are as follows: First，the research status of V incision and the stress intensity factor are introduced. At present, the study of V incision is mainly divided into two categories, namely stress criteria and energy criteria. The stress intensity factor criterion, the maximum circumferential tensile stress criterion, the average circumferential stress criterion are stress criteria. The energy release rate criterion, strain energy density criterion are energy criteria. The studies of these standards are introduced and explained. The stress intensity factor is mechanical constants, reflect the neighborhood near the crack tip or V notch tip singular force. In general, when the fracture safety analysis calculation, it is to calculate the structure of the stress intensity factor K and associated with the magnitude of load, load cracks or incision, geometry; on the other hand, need critical intensity factor determination of material, when t