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Back face rotation correction for trapezoidal specimens
Abstract
Linear-elastic fracture mechanics principles are utilized to determine correction functions for mixed-mode stress intensity factors for edge-cracked trapezoidal specimens by Finite Element Methods.
A comprehensive investigation on the behavior of cracked concrete gravity dams using fracture mechanics concepts through a series of parametric studies is presented. The effect of various forms of loading, concrete age and anisotropy on the stress intensity factors, direction of crack profiles, crack lengths and stress redistribution is assessed.
The evaluation of the safety factor of old darns under higher flood levels in the last few years has been investigated under the assumptions of fracture mechanics. The extensive need for research in this field was recognized by the U.S. Army Corps of Engineers that now requires a fracture mechanics investigation prior to the rehabilitation of cracked massive concrete structures. In large structures, such as dams, because of the smaller size of the fracture process zone with respect to the structure size, limited errors should occur under the assumptions of linear elastic fracture mechanics (LEFM). In this paper, theoretical considerations and approximate expressions for the evaluation of stress intensity factors and crack propagation in concrete dams are presented. Furthermore, a parametric study of gravity dams under the assumptions of LEFM is performed. Finally, a scale law for the evaluation of the maximum water level carried by cracked darns is proposed.
Cracks are often present in concrete dams, and may have relevant dimensions. The evaluation of the safety factor of old dams under higher flood levels has been investigated through fracture mechanics in previous years. Crack stability in concrete dams can correctly be predicted when uplift pressures are accurately modelled. Current models consider a uniform uplift pressure distribution, but recent experimental results show that it varies along the crack faces. In the present paper, uplift pressure effects in cracked concrete gravity dams are studied. A parametric study on the influence of uplift pressure on stress intensity factors and crack-propagation angle is performed. Furthermore, uplift pressure effects on the LEFM scale law for the maximum water level carried by cracked gravity dams are examined.
The application of fracture mechanical technology to massive concrete structures, in particular dams, with special reference to linear and nonlinear methods, and in which validity-studies of material parameters are demonstrated.
Triangular and prismatic quadratic isoparametric elements, formed by collapsing one side and placing the mid‐side node near the crack tip at the quarter point, are shown to embody the (1/√ r ) singularity of elastic fracture mechanics and the (1/ r ) singularity of perfect plasticity. The procedure of performing the fracture analysis for the case of small scale yielding is discussed, and the finite element results are compared with theoretical results.
The proposed elements have wide application in the fracture analysis of structures where ductile fracture is investigated. They permit a determination of the relationship between crack tip field parameters, loading, and geometry. And for a given fracture criterion can be applied to the prediction of fracture in structures such as pressure vessels under in service conditions.
Book on plain strain crack toughness testing of high strength metallic materials
for an edge crack subjected to uniform crack face shearing tractions are given in Figs. 7(a) and 7(b), respectively. Again, the semi-infinite edge-cracked plate result
- Uniformly
- Y Crack Results
- Yi
Uniformly sheared crack Results for Y, and YI, for an edge crack subjected to uniform crack face shearing tractions are given in Figs. 7(a) and 7(b), respectively. Again, the semi-infinite edge-cracked plate result Y(a/w -4; 0) = 1.12 is approached.
Beurteilung von Rißbildungen mit Hilfe der Bruchmechanik angewandt auf Gewichtssperren (Fracture mechanics applied to gravity dams)
- Linsbauer