GROWTH-CHARACTERISTICS OF A FATIGUE CRACK APPROACHING AND GROWING BENEATH AN ADHESIVELY BONDED DOUBLER
GROWTH-CHARACTERISTICS OF A FATIGUE CRACK APPROACHING AND GROWING BENEATH AN ADHESIVELY BONDED DOUBLER
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DOI：
10.1115/1.3443450
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发表时间：
1978-01-01
影响因子：
1.2
通讯作者：
MCGEE, WM
中科院分区：
文献类型：
--
作者：
ANDERSON, JM;CHU, CS;MCGEE, WM
通过实验和数值研究了标题问题。研究中使用了铝被粘物和两种粘合剂 AF-55 和 AF-127。每个样本在未加倍的边缘处都有一条裂纹。应用应力比为 0.1、固定平均远程应力最大值为 103.4 MPa 的疲劳循环来使初始裂纹生长到倍增器上方和下方。测量裂纹扩展速率以评估倍增剂的抑制效果，并进行超声波扫描以确定脱粘区形状。当每条裂纹在倍增器下方约一半处生长后，在倍增器边缘处开始出现二次裂纹，从而加速了样品的破裂。样本的有限元模型采用奇点单元来表示裂纹尖端邻域，并使用剪切弹簧来表示粘合层。模型中释放弹簧以模拟局部脱粘。应力强度因子被计算为裂纹长度的函数，用于实验程序中使用的两种粘合剂的线性和非线性表示。
The title problem was investigated experimentally and numerically. Aluminum adherends and two adhesives, AF-55 and AF-127, were utilized in the investigation. Each specimen had a crack introduced at an undoubled edge. Fatigue cycles with a fixed average remote-stress maximum of 103.4 MPa at a stress ratio of 0.1 were applied to grow the initial crack up to and beneath the doubler. Crack-growth rates were measured to assess the inhibiting effect of the doubler, and ultrasonic scans were made to determine debond-zone shapes. After each crack had grown approximately halfway beneath the doubler, a secondary crack initiated at the edge of the doubler, precipitating rupture of the specimen. A finite-element model of the specimen employed a singularity element to represent the crack-tip neighborhood and shear springs to represent the adhesive layer. Springs were released in the model to simulate local debonding. The stress-intensity factor was computed as a function of crack length for linear and nonlinear representations of the two adhesives used in the experimental program.