Issue 41

F. Berto et alii, Frattura ed Integrità Strutturale, 41 (2017) 260-268; DOI: 10.3221/IGF-ESIS.41.35 268 C ONCLUSIONS he present investigation is aimed to present and apply a useful set of equations able to describe accurately the stress components also in those cases where the mode I and mode II stress intensity factors used in combination with the T-stress, fail to describe the complete stress field ahead the slit tip. A practical example of a thin-thickness welded lap joint characterized by different jointing face width to thickness ratio, ranging d/t from 0.5 to 3, is investigated. The stress field and the strain energy averaged over a control volume can be evaluated with satisfactory precision only taking into account further four other terms besides K I , K II and T. R EFERENCES [1] Williams, M.L., On the Stress at the Base of a Stationary Crack, J. Appl. Mech., Trans. ASME, 24 (1957) 109-114. [2] Rice, J.R., Limitations to the Small Scale Yielding Approximation for Crack Tip Plasticity, J. Mech. Phys. Solids, 22 (1974) 17-26. [3] Larsson, S.G., Carlsson, A.J., Influence of nonsingular stress terms and specimen geometry on small scale yielding at crack tips in elastic-plastic materials, J. Mech. Phys. Solids, 21 (1973) 263–277. [4] Gross, R., Mendelson, A., Plane elastostatic analisys of V-notched plates, Int. J. Fract. Mech., 8 (1972) 267-276. [5] Carpenter, W.C., The eigenvector solution for a general corner of finite opening crack with further studies on the collocation procedure, Int. J. Fract., 27 (1985) 63-74. [6] Ayatollahi, M.R., Pavier, M.J., Smith, D.J., Determination of T-stress from finite element analysis for mode I and mixed mode I/II loading, Int. J. Fract., 91 (1998) 283–298. [7] Chen, Y.Z., Closed form solutions of T-stress in plane elasticity crack problems, Int. J. Solids Struct., 37(11) (2000) 1629–1637. [8] Fett, T., Stress intensity factors and T-stress for single and double-edge-cracked circular disks under mixed boundary conditions, Engng. Fract. Mech., 69 (2002) 69-83. [9] Christopher, C.J., James, M.N., Patterson, E.A., Tee, K.F., Towards a new model of crack tip stress fields, Int. J. Fract., 148 (2007) 361-371. [10] Colombo, C., Du, Y., James, M.N., Patterson, E.A., Vergani L., On crack tip shielding due to plasticity-induced closure during an overload, Fatigue Fract. Eng. Mater. Struct., 33(12) (2010) 766–777. [11] Chen, Y.Z., Lin, X.Y., Wang, Z.X., A rigorous derivation for T-stress in line crack problem, Eng. Fract. Mech., 77 (2010) 753–757. [12] Ramesh, K., Gupta, S., Srivastava, A.K., Equivalence of multi-parameter stress field equations in fracture mechanics, Int. J. Fract., 79 (1996) R37-R41. [13] Ramesh, K., Gupta, S., Kelkar, A.A., Evaluation of stress field parameters in fracture mechanics by photoelasticity- revisited, Engng Fract. Mech., 56(1) (1997) 25-45. [14] Ayatollahi MR, Nejati M. An over-deterministic method for calculation of coefficients of crack tip asymptotic field from finite element analysis Fatigue Fract. Engng Mater. Struct., 34 (3) (2011) 159–176. [15] Xiao, Q.Z., Karihaloo, B.L., Liu, X.Y., Direct determination of SIF and higher order terms of mixed mode cracks by a hybrid crack element, Int. J. Fract., 125(3-4) (2004) 207–225. [16] Xiao, Q.Z., Karihaloo, B.L., An overview of a hybrid crack element and determination of its complete displacement field, Eng. Fract. Mech., 74 (2007) 1107-1117. [17] Lazzarin, P., Berto, F., Radaj, D., Fatigue-relevant stress field parameters of welded lap joints: pointed slit tip compared with keyhole notch. Fatigue Fract. Eng. Mater. Struct., 32 (2009) 713–735. [18] Berto, F. and Lazzarin, P. (2010) On higher order terms in the crack tip stress field. International Journal of Fracture, 161, 221–226. . T