ORIGINAL CONTRIBUTION Free Edge Mixed Mode Delamination Analysis of Laminated Composites with Wrap-Around Configuration: A Finite Element Study Pannalal Choudhury 1 . Subhankar Das 1 . Sudipta Halder 1 . Krishna Murari Pandey 1 Received: 12 August 2015 / Accepted: 30 September 2015 Ó The Institution of Engineers (India) 2015 Abstract Finite element analyses of laminated compos- ites were done in the present study with respect to sup- pression of free edge delamination by an innovative technique. Wrap-around configuration was considered to determine its effectiveness over the wrapper-less laminated configuration on laminated composites. Nodal stresses were generated ahead of the crack tip through finite ele- ment analysis. This was used for determining interlaminar normal stress and inter laminar shear stress distributions at the critical interface. Later virtual crack closure technique was used to estimate the strain energy release rate com- ponents for several sizes of virtual crack extensions through a single finite element analysis. Computational analysis predicts Mode-I delamination as dominant mode of failure. This mode of delamination was significantly suppressed with wrap-around configuration on laminated composites. Keywords Finite element analysis Á Free edge delamination Á Strain energy release rate Á Virtual crack closure technique Introduction Importance of laminated fibre reinforced polymer com- posite has been found not only in high performance industries such as aerospace, automobile and defence but also in industries where secondary load bearing structures are of primary interest [1]. However, one of the major concern to use such laminated composite is their low inter laminar toughness making them liable to delaminate at free edges near the regions of high stress gradient. This free edge delamination behaviour is found to be dependent on interlaminar fracture (defined as the cracking of the matrix between plies) caused by high interlaminar stresses that arise due to mismatch in elastic properties between plies at free edges in composite laminates. In most of the cases conventional lay-up technique are prone to free edge delamination thereby enhancing the defect density in laminated composite structures, resulting in premature failure. This defect density and their growth in laminated composite may lead to severe reliability and safety issues, such as reduction of structural stiffness, strength, fatigue life and disintegration of the laminated composite struc- tures [2]. To overcome such difficulties different tech- niques have been used by scientists and technologists for suppressing the propagation of interlaminar cracks. One of such technique is the use of wrapper on the laminates. U-shaped partial wrapper configurations are one of those efforts that have been applied by scientists [3–5]. Enor- mous capability of restraining has been found with U-Shaped configuration which improves strength and fatigue life [3, 4]. In this regard throughout wrapping configuration may further enhance the effect over the U-shaped configuration. Various studies have been repor- ted on computational analysis of edge delamination behavior [6, 7]. In most of the cases, mechanism of delamination considered is governed by crack separation between adjacent laminae by crack formation at interfacial sites within the laminates [8, 9]. Over the past two decades, this phenomenon is, in general, quantified by researchers using fracture mechanics by determining the fracture toughness of the material [10, 11]. In previous studies & Pannalal Choudhury choudhury100@yahoo.co.in 1 Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar, Assam 788010, India 123 J. Inst. Eng. India Ser. D DOI 10.1007/s40033-015-0099-z