Aiaa Paper 71-113
1 Grief. R. and Sanders. J. L The effect of a stringer on the stress in it cracked sheet. Harvard University TR 18 1963 . 2 Vlieger. H. and Broek, D Residual strength of cracked stiffened panels. Built up shed .srnicnires. AGARD Fracture Mechanics Survey 1974 . 3 Vlieger. H Residual strength of cracked stiffened panels. Eng. Fracture Mechanics. 5 1973 pp. 447-478. 4 Poe. C. C Fatigue crack propagation in stiffened panels. ASTM ST P. 1971 pp. 79 97. 5 Poe. C. C The effect of riveted and...
2 A
Note that division by B is necessary because the energy release rate is always given per unit thickness. Eq 9.40 was derived for the case that i i is small, but this restriction is not necessary, since an equation similar to eq 9.34 can be written for pct 41 which leaves the derivation of eq 9.40 essentially Figure 9.16. Procedure for experimental measurement of J c unchanged. Thus eq 9.40 is a general expression for specimens with ligaments in bending. The elastic part can be separated out to...
22 Cleavage fracture
F igure 2.6. Brittle-ductile transition of steel F igure 2.6. Brittle-ductile transition of steel graphic plane. Iron for example cleaves along the cube planes 100 of its unit cell. This causes the relative flatness of a cleavage crack within one grain, as indicated in figure 2.7. Since neighbouring grains will have slightly different orientations, the cleavage crack changes direction at a grain boundary to continue propagation on the preferred cleavage plane. The flat cleavage facets through...
18 da E
per unit plate thickness, where E is Young's modulus. Usually dU da is replaced by which is the so called elastic energy release rate per crack tip. G is also called the crack driving force its dimensions of energy per unit plate thickness and per unit crack extension are also the dimensions of force per unit crack extension. The energy consumed in crack propagation is denoted by R dW da which is called the crack resistance. To a first approximation it can be assumed that the energy required to...
14 The Griffith criterion
Although fracture mechanics have been developed mainly in the last two decades, one of the basic equations was established already in 1921 by Griffith 9, 10 . Consider an infinite cracked plate of unit thickness with a central transverse crack of length 2a. The plate is stressed to a stress a Figure I X. The Griffith criterion for fixed grips a. Cracked plate with fixed ends b. Elastic energy and fixed at its ends as in figure 1.8a. The load displacement diagram is given in figure 1.8b. The...