【摘要】 给出一个中心裂纹圆盘断裂试验的较完整的试验技术,并用此试验技术在岛津材料试验机上对有机玻璃(polymethyl methacrylate,PMMA)这种典型的脆性材料成功地进行纯Ⅰ型、纯Ⅱ型和复合型加载条件下的断裂试验。试验结果表明,纯Ⅰ型、纯Ⅱ型及复合型加载条件下,载荷分布角γ大于8°,对KⅠ和KⅡ的试验结果有较大影响;纯Ⅰ型加载条件下裂纹是自相似扩展的,纯Ⅱ型和复合型加载条件下裂纹是非自相似扩展,且起裂始于切口端部的角点处。试验结果和有限元分析结果表明,最大周向拉应力准则对于预测非理想裂纹切口试件的开裂角仍然是有效的,但必须以实际试件切口端部角点处的应力场为依据。更多还原

【Abstract】 The fracture toughness testing technique for the central cracked circular disk specimen is given to investigate the fracture behavior of brittle material polymethyl methacrylate(PMMA) under pure mode Ⅰ,pure mode Ⅱ and mixed-mode loadings.The experimental results show that the load distribution angle is always greater than 8° for all different loading conditions.Such load distribution has an important effect on the determination of the fracture toughness K_Ⅰ and K_Ⅱ.The crack propagates in a direction parallel to the original crack plane under pure mode Ⅰ loads.However,under pure mode Ⅱ and mixed-mode loading conditions,the direction of crack propagation deviates from the original crack plane and the crack propagation begins at the corner of the notch.The experimental results and FEM(finite element method) analysis indicate that the maximum hoop stress theory is still valid to predict the crack propagation direction of the specimen which has a notch not an ideal crack,based on the stress field at the corner of the notch.更多还原