Person: EKİCİ, BÜLENT
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EKİCİ
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BÜLENT
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Publication Metadata only The effects of static, dynamic and fatigue behavior on three-dimensional shape optimization of hip prosthesis by finite element method(ELSEVIER SCI LTD, 2007) EKİCİ, BÜLENT; Kayabasi, Oguz; Ekici, BulentThe finite element method, one of the most advanced simulation techniques in solid mechanics, is used for orthopedic biomechanics. It is used as a tool for the design and analysis of total joint replacement and other orthopedic devices. The design of hip joint prostheses is a complex process that requires close co-operation between engineers and surgeons. To design highly durable prostheses one has to take into account the natural processes occurring in the bone. One of the most important factors in the implant design is to reduce stress on the femur and the bone-cement. The purpose of this study is to investigate the behavior of newly designed implants under body weight load during stumbling by parametric modeling. Two different implant materials have been selected to study appropriate material and fatigue life resistant. In the parametric design, the prosthesis functional requirement is that the locking of stem to the femur head using cement should be strong enough to preclude unlocking during the life time of a patient and to prevent sliding of the implant into the bone-cement. In the finite element analysis, physical interactions among joints are simulated by contact algorithms. The femur-bone-cement interface and the bone-cement-implant interface surface to surface contact algorithms of ANSYS were used for implicit static analysis. Three stem-cement interface conditions are considered: completely bonded, debonded with coefficient of friction 0, and debonded with coefficient of friction 0.2. In the analysis, a viscoelastic material model is utilized for bone-cement. Numerical shape optimization is applied to the prosthesis. The results of finite element simulations are compared with Charnley's implant results and appropriate material for the implant is proposed. The best stem shapes fulfilling the desired functional requirements are chosen for the design. These findings can form a base for further research such as the optimum design of bone-implant hip prosthesis. (C) 2006 Published by Elsevier Ltd.Publication Metadata only Effect of solution blown nanofibers on Mode-I fracture toughness and dynamic mechanical properties of carbon fiber-reinforced composites(WILEY, 2021) EKİCİ, BÜLENT; Polat, Yusuf; Ekici, Bulent; Kilic, AliIn this study, solution-blown nanofibers were coated on carbon fiber (CF) fabrics to improve Mode-I fracture toughness and dynamic mechanical properties of the composite laminates. Nanofiber coatings of various basis weights were directly spun over CF fabrics, which were then formed into composite laminates via vacuum-assisted resin transfer molding. A double cantilever beam test was conducted to analyze the Mode-I fracture toughness of CF-reinforced epoxy composites. The results showed that solution-blown nanofiber coatings stabilized the crack propagation and increased the delamination strength hence increased the Mode-I fracture toughness by nearly 48% for the addition of 1 g/m(2) nanofibrous web. Dynamic mechanical analysis was performed to investigate the effect of nanofibers on the stiffness of materials and the homogeneity of samples. Storage modulus, loss modulus, and damping factor were calculated, and corresponding Cole-Cole plots were drawn. DMA results showed that the stiffness of the composite sample increased up to 17% even after a minor amount (1 g/m(2)) of nanofiber coating.