Papers by Keyword: Progressive Failure Analysis

Abstract: The usage of laminated glass fiber reinforced polyester composites in aerospace applications helps to reduce overall weight of the aerospace structures. The flexural strength of the laminated glass fiber reinforced composites becomes more important when they are employing for aeroplane wings. In this work, a laminated glass fiber polyester composite with two distinct sets of six different woven lamina stacking sequences is manufactured via hand layup technique. The effect of stacking sequence over the total ply failure load are investigated through universal testing machine. Finally, the progressive failure of the lamina in composites is also examined using ANSYS software.

Abstract: Constructions of pressure vessels like rocket launch vehicles, missiles, rocket propellant tanks, and filament wound pipes for civil and military applications are made out of high strength, high stiffness and light weight composites filaments. Filament winding techniques are used for fabrication of such cylinders and pipes. Many materials like glass fibers, carbon fibers and Kevlar fibers are used due to their good strength when it is subjected to internal pressure as well as external pressure. Basalt fibers are new materials that are fabricated from hard dense basalt rocks. Basalt fibers can be used in the place glass fibers due to their good mechanical behavior when subjected to internal pressure. Plates and beams generally resists bending loads and pipes and tube structures resists internal forces developed through internal and external pressure. This work concentrates the fabrication of filament wound pipes using filament wound techniques and the burst pressure test is carried out. In fuel tanks of rockets, If any one of the layer fails due to internal pressure, there will be mild leakage. For this reason it is mandatory to find out the ply by ply failure. The first ply failure of basalt filament wound pipes subjected to internal pressure is calculated using Finite element analysis. Then the stress and progressive failure analysis was carried out. Maximum stress failure criterion is used for the finite element analysis.

Abstract: A finite element analysis procedure is developed for progressive failure analysis of laminated composite plates under in plane tensile loading. A finite element model is based on higher order shear deformation theory (HSDT) with seven degrees of freedom. The degradation technique used for degradation of material properties of a failed ply is a ply discounting approach. The mode dependant Hashin and Lee failure criterion is used for the progressive failure analysis. The results of first ply failure load and last ply failure load are obtained for different stacking sequence of composite plate. The results shows that a considerable amount of strength remains un utilized in composite laminates after first ply failure of laminates.

Abstract: Failure prediction of adhesively bonded single-lap laminates joints with spew fillets in the overlap ends under uniaxial tensile loading is performed by progressive failure analysis method. A modified form of Hashins failure criterion by Shokrieh and maximum stress criterion are used to detect the laminate failure and adhesive failure, respectively, where a sudden degradation model is proposed to reduce engineering material constants. Five kinds of failure modes are considered. The numerical analysis of composites adhesive joints is implemented in ANSYS Parametric Design Language (APDL) with commercial finite element codes ANSYS. The error of simulation and experimental failure loads is 6.9% and the model has been validated by comparing numerical results with experimental results.

Abstract: Failure prediction of laminated composites is performed by progressive failure analysis method. A modified form of Hashin’s failure criterion by Shokrieh is used to detect the failure, where a sudden degradation model is proposed to reduce engineering material constants. The numerical analysis of composite laminates is implemented in ANSYS Parametric Design Language (APDL) with commercial finite element codes ANSYS. The method can predict the initiation and propagation of local damage and response of laminated composite structures from initial loading and ultimate failure. The model has been validated by comparing numerical results with existing experimental results. And then failure analysis specimen fabricated from M40J/Ag80 and investigation on influence of stacking sequences and fiber orientations under in-plane compressive loading have been performed by the proposed model.

Abstract: Failure analysis of laminates is performed by progressive failure analysis method. A modified form of Hashin’s failure criterion by Shokrieh is used to detect the failure, where a sudden degradation model is proposed to reduce engineering material constants. The numerical analysis of composite laminates is implemented in ANSYS Parametric Design Language (APDL) with commercial finite element codes ANSYS. The method can predict the initiation and propagation of local damage and response of laminated composite structures from initial loading and ultimate failure. The model has been validated by comparing numerical results with existing experimental results. And then failure analysis specimen fabricated from M40J/Ag80 and investigation on influence of stacking sequences and fiber orientations have been performed by the proposed model.

Abstract: A method was developed to predict numerically the dent depth of composite laminates subjected to quasi-static indentation. A progressive damage analysis was conducted for composite laminates under quasi-static transverse compressive loading by using a strain based Hashin and Yeh failure criteria as well as the FEM, and a series of degraded elastic constants of the damaged zone were drawn from the numerical results. The effective elastic constants of the damaged zone of the laminates were reevaluated according to Sun’s explicit expression. Finally, the dent depth vs. indentation force curve was predicted based on Swanson’s contact theory. The numerical simulations on the static indentation tests of T700/BA9912, T700S/5228 and T700/QY9511 laminates were done via this method. The numerical results agree well with the test data in the terms of the contact force and the corresponding dent depth.

Abstract: In this article a methodology based upon micromechanical analysis of multiple damage events is developed to predict stress-strain response and failure behavior of fiber-reinforced polymers composites under tensile loading, by considering the effect of variations in fiber strength and local shear failure of the matrix. A simulation scheme coupled with Monte-Carlo method including these failure mechanisms is proposed to investigate failure process and determine ultimate strength of the composites. It is shown that the size dependence of composite ultimate strength is dominated by fiber strength statistics and stress distribution due to progressive microdamage.

Abstract: The progressive failure analysis of composite pressure vessel under hydrostatic pressure has been carried out. The composite pressure vessel has been modeled by using layer structural shell element. After the failure of the weakest ply, the stiffness is reduced by either fiber failure or matrix failure. The stiffness of failed element has been totally discarded and other element are considered to remain unchanged after the weakest ply failure. The stress of the laminate at the same point is evaluated again to see if the laminate can carry additional load. This ply-by-ply analysis progresses until the ultimate strength of the pressure vessels is reached. A parametric study has been done on the progressive failure analysis.