Research Article Finite Element Modeling of Laminated Composite Plates with Locally Delaminated Interface Subjected to Impact Loading Saddam Hussein Abo Sabah and Ahmad Beng Hong Kueh Construction Research Centre, Universiti Teknologi Malaysia (UTM-CRC), 81310 Johor Bahru, Johor, Malaysia Correspondence should be addressed to Ahmad Beng Hong Kueh; kbhahmad@utm.my Received 31 August 2013; Accepted 25 December 2013; Published 13 February 2014 Academic Editors: J. R. d’Almeida and G. Nikas Copyright © 2014 S. H. Abo Sabah and A. B. H. Kueh. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. his paper investigates the efects of localized interface progressive delamination on the behavior of two-layer laminated composite plates when subjected to low velocity impact loading for various iber orientations. By means of inite element approach, the laminae stifnesses are constructed independently from their interface, where a well-deined virtually zero-thickness interface element is discreetly adopted for delamination simulation. he present model has the advantage of simulating a localized interfacial condition at arbitrary locations, for various degeneration areas and intensities, under the inluence of numerous boundary conditions since the interfacial description is expressed discretely. In comparison, the model shows good agreement with existing results from the literature when modeled in a perfectly bonded state. It is found that as the local delamination area increases, so does the magnitude of the maximum displacement history. Also, as top and bottom iber orientations deviation increases, both central delection and energy absorption increase although the relative maximum displacement correspondingly decreases when in contrast to the laminates perfectly bonded state. 1. Introduction Interfacial imperfection that eventually leads to the delam- ination of laminated composite plates is commonly consid- ered as one of the chief contributors to performance degra- dation of these advanced lightweight materials. his imper- fection is structurally harmful and contributes principally to the failure of the laminate especially in presence of dynamic loading environment such as impact loading. he imperfec- tion in the interface may be due to insuicient adhesion or incorrect equipment setting during manufacturing, leading it to undergo serious damage such as matrix cracks, ibers breakages, or delamination. hese kinds of damage are severe because they drastically reduce the mechanical characteristics of the laminate and at the same time can leave visible marks on the impacted surface. herefore, understanding the interface condition efect on laminated composite plates is of great importance for improvement of the plate’s strength. In terms of loading environment, laminated composite plates are prone to impact loads that occur during manufac- turing, transportation, or service life. hese impact loads are considered extremely dangerous and cause invisible damage to the back face or within the laminate which consequently reduce the strength of the composite material, even when the impact produces low energy. It has been proven that if a com- posite plate is subjected to a low velocity impact, the damaged area will increase with the increase of the impact velocity [1]. Caprino et al. [2] concluded that the irst failure point in a laminated composite plate is inluenced more by the impact speed rather than the impacting energy. In much similar vein, a inite element model was developed to study the response of laminated composite folded plates subjected to impact loads [3]. he results indicate that, under impact loading, the amplitude and period of a laminated composite folded plate tend to increase. he damage caused by the impact load is very obvious on the face of the plate. In general, there exist several factors that signiicantly inluence the behavior of composite materials when subjected to impact loading. hey can basically be divided into two parts. he irst part involves the laminate properties such as shape, size, thickness, ply orientation, and stacking sequence. Hindawi Publishing Corporation e Scientific World Journal Volume 2014, Article ID 954070, 11 pages http://dx.doi.org/10.1155/2014/954070