S. K. Kudari et alii, Frattura ed Integrità Strutturale, 39 (2017) 216-225; DOI: 10.3221/IGF-ESIS.39.21 216 3D Stress intensity factor and T-stresses (T 11 and T 33 ) formulations for a Compact Tension specimen S. K. Kudari Department of Mechanical Engineering, CVR College of Engineering, Hyderabad, India s.kudari@rediffmail.com K. G. Kodancha Research Centre, Department of Mechanical Engineering, BVB College of Engineering & Technology, Hubli, India krishnaraja@bvb.edu A BSTRACT . The paper describes test specimen thickness effect on stress intensity factor (K I ), and T-stresses stresses (T 11 and T 33 ) for a Compact Tension specimen. Formulations to estimate 3D K I , T 11 and T 33 stresses are proposed based on extensive 3D Finite element analyses. These formulations help to estimate magnitudes of 3D K I and T 11 and T 33 which are helpful to quantify in-plane and out-of- plane constraint effect of the crack tip. The proposed formulations are validated with the similar results available in literature and found to be within acceptable error. K EYWORDS . Constraint effects; 3D Finite element analysis; Stress intensity factor; T-stress; CT Specimen. Citation: Kudari, S. K., Kodancha, K. G., 3D Stress intensity factor and T-stresses (T 11 and T 33 ) formulations for a Compact Tension specimen, Frattura ed Integrità Strutturale, 39 (2017) 216-225. Received: 25.09.2016 Accepted: 31.10.2016 Published: 01.01.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION tress tri-axiality at the crack-tip can alter crack-tip constraint and fracture toughness values of a material. This is the reason transferability of fracture toughness data estimated using laboratory test specimens to a full-scale cracked structure is an important issue in structural integrity assessment of engineering materials. In LEFM non-zero non- singular terms in the series expansion of three-dimensional stress field [1] referred as T-stresses (T 11 and T 33 ) can alter the crack-tip stress tri-axiality and are considered as constraint parameters [2]. T 11 (the second term of William’s extension acting parallel to the crack plane) plays an important role on the in-plane constraint effect. The thickness at the crack tip contributes to the out-of-plane constraint, T 33 (the second term of William’s extension acting along the thickness). To transfer fracture toughness data under different constraints, both in-plane and out-of-plane constraint effect should be considered for the specimens. S

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