Recent Research in Science and Technology 2014, 6(1): 176-179 ISSN: 2076-5061 Available Online: http://recent-science.com/ Simulation study of stiffeners on composite plate Mohd. Asghar Zaidi 1 , M. N. Javed 2 , Soni Kumari 2 and Ashish Kumar 1 1 Department of Mechanical Engineering Rajshree Institute of Management & Technology, Bareilly, India. 2 Department of Mechanical Engineering, GLA University, Mathura, India. Abstract The present communication highlights a computational model to analyze the behavior of stiffened plates of such composite materials that is subjected to low velocity impact. The commercial explicit finite element software LS-Dyna has been used. The contact force is calculated in conjunction with the loading and unloading processes. The time history of the impact process such as target plate deflection, due to an impact force acting at the center of the plate, is obtained. Analysis shows the effect of number of stiffener on response of composite plate. In particular the displacement and contact force curve with respect to time were investigated, as the stiffness of the composite plate and contact force variation with time were analyzed without failure of composite structure with single and double stiffener. Keywords: Composite material, Impact load, Low velocity impact INTRODUCTION During the life of a structure, impacts by foreign objects can be expected to occur during manufacturing, service, and maintenance operations. An example of in-service impact occurs duringthe manufacturing process or during maintenance; tools can be dropped on the structure. In this case, impact velocities are small; but the mass of the projectile is larger. In composite structures, impacts create internal damage that often cannot be detected by visual inspection. This internal damage can cause severe reductions in strength and can grow under load. Therefore, the effects of foreign object impacts on composite structures must be understood, and proper measures should be taken in the design process to account for these expected events. Concerns about the effect of impacts on the performance of composite structures have been a factor in limiting the use of composite materials. Laminated composite plates are quite susceptible to damage when subjected to low velocity impact by a foreign object and plate structures, when stiffened, attain a greater strength with a small increase of weight. Composite stiffened pate structures are efficient from the point of view of higher strength, material economy as well as ease of construction. In addition to the light weightiness obtained from composites, the stiffened system itself provides much higher stiffness for a specified structural weight. In relation to above-mentioned advancement in the use of composite stiffened structures, analysis of these systems has become an important prerequisite prior to their design and construction. The behavior of composite structures subjected to low velocity impact has been studied by numerous researchers, including experimental, numerical and analytical works. Caprino et al[1984] used a simple model, based on energy considerations, which has been tested to predict the behavior of a composite plate subjected to low-velocity impact. To calculate the maximum contact force during impact a force displacement curve for the structure has been used, area under the curve is compared with kinetic energy of impactor to calculate maximum contact force.Yigit and Christoforou [1995] developed a more realistic linearized contact law based on elastic- plastic contact law including the permanent indentation effects. The contact law was derived by combining the classical Hertzian contact theory and elastic-plastic indentation theory for metallic bodies.Vaziri et al[1996] used a super finite element method that exhibits coarse- mesh accuracy to predict the transient response of laminated composite plates and cylindrical shells subjected to non-penetrating impact by projectiles.Oguibe& Webb [1999] investigated the impact response of a laminated composite square plate using the finite element technique. An approximate failure mode has been incorporated into the model by a combination of spring, gap and dashpot elements to account for the energy dissipated during the damage process. Abrate [2001] provided a detail review on various analytical models of impact on composite laminates. He classified impact models into four groups: energy balance models, spring-mass models, complete models and impact on infinite plate model. Her &Liang[2004] investigated, the composite laminate and shell structures subjected to low velocity impact are studied by the LS- DYNA finite element software. The contact force is calculated by the modified Hertz contact law during and unloading processes.Chunand&Kassegne[2005] used the higher-order shear deformation theory is used to study the response of graphite/epoxy laminated composite non-prismatic folded plates subjected to impact loads.Tiberkak et al [2006] In this investigation, the fiber-reinforced composite plates, without damage, subject to low velocity impact was studied by the use of finite element analysis (FE). To analyze the response of the plate, a Newmark time integration algorithm was used.Tiberkak et al[2008] investigated, fiber-reinforced composite plates subjected to low velocity impact are studied by the use of finite element analysis. Mindlin‟ s plate theory is implemented into the FE approach in which a 9-node Lagrangian element is considered. Setoodeh et al [ 2009] coupled a generalized layer wise finite *Corresponding Author Mohd. Asghar Zaidi Department of Mechanical Engineering Rajshree Institute of Management & Technology, Bareilly, India. email: zaidicc0901@gmail.com