Dynamic fracture initiation criterion in ceramics under combined mode impact loading

组合模式冲击载荷下陶瓷的动态断裂萌生准则

• 批准号: 04650066
• 负责人: NAKANO Motohiro
• 金额: $ 1.41万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04650066/
• 关键词: Impact fracture; Mixed-mode fracture; Ceramics; Fracture toughness; Stress sitensity factor; Fracture criterion; Alumina; Loading rate effect; 衝激破壊試験

Recent progress in ceramics industries has enabled us to use high performance ceramics for manufacturing components of machinery such as turbines. However, the use of high performance ceramics has required further investigation in dynamic fracture mechanics.In an ordinary case that an impact load acts on a structure, stress waves obliquely impinge to various cracklike flaws in the structural components. The stress waves produce mixed-made stress states around the crack-tips. Thus the dynamic fracture initiation criterion under combined mode loading has to be made clear for assessments of structural integrity in relation to the impact fracture.For the accurate evaluation of the dynamic fracture criterion, we have developed a new test method for mixed-mode impact fracture using the centerprecracked disk specimen. The impact fracture tests canbe performed under arbitrary combinations of mode I and II by varying the inclibation angle of the centerprecrack. The dynamic fracture toughness values of mode I and II are determiced form critical dynamic stress intensity factors at fracture initiation. The dynamic stress intensity factors are calculated by superposing the step-response functions with respect to the impact load history measured in the fracture test. The stepresponse fuctions have been obtained from finite element analyzes for the precracked disk specimen. The onset of fracture initiation is detected using the strain gage near the crack-tip.In the resent research, dynamic and static fracture tests are performed for alumina ceramics and some brittle materials under combined mode loadings. The dynamic results are compared with the quasi-static data obtained in diametralcompression fracture tests, and fitted to a simple empirical eriterion proposed in this study.

陶瓷行业的最新进展使我们能够使用高性能陶瓷来制造涡轮机等机械部件。然而，高性能陶瓷的使用还需要进一步研究动态断裂力学。在冲击载荷作用于结构的通常情况下，应力波倾斜地冲击结构部件中的各种裂纹状缺陷。应力波在裂纹尖端周围产生混合应力状态。因此，必须明确组合模式加载下的动态断裂起裂准则，以评估与冲击断裂相关的结构完整性。为了准确评估动态断裂准则，我们开发了一种新的混合模式冲击断裂测试方法使用中心预裂的圆盘样本。通过改变中心预裂纹的倾斜角度，可以在模式 I 和 II 的任意组合下进行冲击断裂试验。模式 I 和 II 的动态断裂韧性值由断裂起始时的临界动态应力强度因子确定。通过将阶跃响应函数与断裂试验中测得的冲击载荷历史叠加来计算动态应力强度因子。通过对预裂纹圆盘样本的有限元分析获得了阶跃响应函数。使用裂纹尖端附近的应变计来检测断裂起始的发生。在最近的研究中，对氧化铝陶瓷和一些脆性材料在组合模式载荷下进行了动态和静态断裂试验。将动态结果与径向压缩断裂试验中获得的准静态数据进行比较，并拟合到本研究中提出的简单经验方程。

项目成果

Motohiro Nakano and Keizo Kishida: ""Mixed-Mode Impact Fracture Tests Using Center-Notched Disk Specimens"" Proc. International Symposium on Impact Engineering. Vol. II. 581-586 (1992)

Motohiro Nakano 和 Keizo Kishida：“使用中心缺口盘样本的混合模式冲击断裂测试”Proc。

M.Nakano,K.Kishida,Y.Yamauchi,Y.Sogabe: "Dynamic fracture initiation in brittle materials under combined mode I/II loading" Proc.Int.Conf.on Mech.& Phys.Behav.Mat.under Dynamic Loading. (in print). (1994)

M.Nakano、K.Kishida、Y.Yamauchi、Y.Sogabe：“组合模式 I/II 载荷下脆性材料的动态断裂起始”Proc.Int.Conf.on Mech。

Motohiro Nakano and Keizo Kishida: "Mixed-Mode Impact Fracture Tests Using Center-Notched Disk Specimens" Proceedings of The International Symposium on Impact Engineering. Vol.II. 581-586 (1992)

Motohiro Nakano 和 Keizo Kishida：“使用中心缺口盘样本的混合模式冲击断裂测试”国际冲击工程研讨会论文集。

Motohiro Nakano, Keizo Kishida, yoshiaki Yamauchi and Yuji Sogade: ""Dynamic Fracture Initiation in Brittle Materials under Combined Mode I/II Loading"" Proc. International Confernce on Mechanical and Physical Behavior of Materials under Dymanic Loading.

Motohiro Nakano、Keizo Kishida、yoshiaki Yamauchi 和 Yuji Sogade：“组合模式 I/II 加载下脆性材料的动态断裂引发”Proc。

M.Nakano,K.Kishida,Y.Yamauchi and Y.Sogabe: "Dynamic Fracture Initiation in Brittle Materials under Combined Mode I/II Loading" Proc.Int.Conf.on Mechanical and Physical Behavior of Materials under Dynamic Loading. in print. (1994)

M.Nakano、K.Kishida、Y.Yamauchi 和 Y.Sogabe：“组合模式 I/II 载荷下脆性材料的动态断裂引发”Proc.Int.Conf.on 动态载荷下材料的机械和物理行为。