Issue 33

J. Fan et alii, Frattura ed Integrità Strutturale, 33 (2015) 463-470; DOI: 10.3221/IGF-ESIS.33.51 463 Weight Function Method for computations of crack face displacements and stress intensity factors of center cracks Junling Fan, Dengke Dong, Li Chen, Xianmin Chen AVIC Aircraft Strength Research Institute, Xi’an 710065, China fanjunling@mail.dlut.edu.cn Xinglin Guo State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China A BSTRACT . The weight function method provides a powerful and reliable tool for the determination of the stress intensity factor around the crack tip in a linearly elastic cracked solid subjected to arbitrary loading conditions. However, it is difficult to exactly compute the crack face displacement whose partial derivative is responsible for the weight function calculation. In the present paper, only one reference stress intensity factor is used for the purpose of establishing a general expression of the crack face displacement. Then, the generalized and simple expression is applied to calculate the weight function and the stress intensity factor of the center crack configuration. The calculation of the weight function is reduced to the simple integration of the correction function and of the partial derivative of the crack face displacement. It is shown that the present expressions for the computations of the crack face displacement and its partial derivative are in good agreement with their exact solutions. K EYWORDS . Weight function; Crack face displacement; Stress intensity factor; Center crack configuration. I NTRODUCTION s is known, the stress intensity factors (SIFs) dominate the singular stress states around the crack tip. Thus, the calculation of the SIFs is of quite importance for assessing the load capacity, fatigue crack growth rate and fracture failure control of a cracked component. Although the SIFs are possibly available in some of the SIF handbooks [1], the documented solutions are sometimes inapplicable in practical problems due to complicated non-linear stress fields. The weight function method provides a reliable method to calculate the SIF around a crack tip in a 2D linearly elastic body subjected to any arbitrarily chosen load systems [2]. Wu and Carlsson [3] presented the generalized weight function method based on the physical judgment on the shape of the opened crack, and subsequently derived the SIFs for center cracks in finite width plates with mixed boundary conditions. Shen and Glinka [4] used two linearly independent reference stress intensity factors together with the characteristic properties of the weight function to determine the three unknown parameters in the universal weight function. Overall, the weight function method makes it possible to determine exact and reliable stress intensity factors which are useful for the evaluation of fatigue crack growth and residual strength of aircraft structures in service. A