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چكيده انگليسي :

Nonlinear Finite Element Analysis of Composite Corrugated Boards With Elastomeric Coatings Iman Dayyani Email Iman dayyani@gmail com Date of submission 30 12 2011 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language Farsi Supervisor Saeed Ziaei Rad Email szrad@cc iut ac irAbstractSandwich structures have been used over a long time applications where the weight of the member is critical such as packaging civil naval automotive and aerospace industries due to their low mass to stiffness ratio andhigh impact absorption capacity Some instances of their applications in daily life are cardboard sandwich coresused for packaging metal corrugated roofs hulks automotive chassis and bumpers fuselage and morphing wing In nature where mechanical design required to be optimized sandwich structures are used such as the humanskull which is made up of two layers of dense compact bone separated by a core of lower density material Composite corrugated panels as a branch of sandwich structures have exceedingly anisotropic behavior They arestiff and flexible along and transverse to the corrugation direction respectively Composite corrugated panelshave been proposed as a candidate for application in morphing wings This is due to the fact that wing structuresmust be stiff so as to withstand bending due to aerodynamic forces and flexible so as to match the most efficientform in a flight regime In addition high fatigue resistance of composite corrugated panels in morphing wingapplication is another advantage of these structures Tensile hysteresis and flexural characteristics of compositecorrugated laminate with and without elastomeric coatings were studied using experimental numerical andanalytical investigations Prepreg laminates of glass fiber plain woven cloth were hand laid by use of a heat gunto ease the creation of the panel The corrugated panels were then manufactured by using a trapezoidal machinedaluminium mold Next upper and lower faces of the corrugated core were coated by elastomer In order toevaluate the mechanical characteristics of materials a series of tension tests were performed on standard samplesof composite laminates and elastomer strips Cyclic loading behavior of elastomers in different directions wasinvestigated Next the coated panels were subjected to tensile hysteresis and three point bending tests For thefirst time the mechanical behavior of the panel in tension and three point bending tests was simulated In order tomodel the energy dissipation due to delamination phenomenon observed in tensile tests in all members of coatedcorrugated core plastic behavior was assigned to the whole geometry not only to the corner regions The resultsreveal that the mechanical behavior of this structure in tension is sensitive to the variation of core height Inaddition the behavior of composite corrugated core with and without elastomeric coatings was studied andverified in bending Finally the numerical results were validated by comparing them with experimental data Good correlation illustrating the suitability of finite element model for predicting the mechanical behavior ofcoated panels was observed Moreover considering the non smooth surface of corrugated panel during bending two concepts to deal with this drawback were proposed Furthermore the mechanical behavior of bi directionalcomposite corrugated core with elastomeric coatings in tensile and bending experiments was studied numerically Keywords Composite corrugated core Finite element analysis Glass fiber Elastomer Three point bending test Tensile test Hysteresis test

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