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Effects of temperature on the evolution of stresses at the stem cement interface
Kaci, Djafar Ait,Moulgada, Abdelmadjid,Achache, Habib,Bounoua, Noureddine Techno-Press 2019 Advances in computational design Vol.4 No.3
The insertion of femoral implants is the most important phase for surgeons, given the characteristics of the cement during its mixing phase, generating residual stresses of thermal origin that increase the different stresses induced in the bone cement. The aim of our study is to determine the different stresses that affect the cement and more particularly at the cement-implant interface for different temperatures, and to make a comparison with the cement at ambient temperature. It was concluded that, there are a large concentration of stresses in the proximal part of the cement. For normal stresses, the bone cement is affected by stresses of tension and compression due to the effect of polymerization and the contraction of the cement.
Ait Kaci Djafar,Zagane Mohammed El Sallah,Moulgada Abdelmadjid,Sahli Abderahmane 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.6
The objective of this study is to investigate the distribution of von Mises stress, peeling stress, and shear stress in the adhesive layer used to bond two composite panels, considering various parameters using a three-dimensional finite element method. The stiffness of the materials and the effect of the stacking order on the amount of load transferred to the adhesive layer were examined to determine which type of laminate generates less stress at the bond line. The study analyzed six different stacking sequences, all with a common first layer in contact with the adhesive and a 0° orientation. Additionally, the impact of using hybrid composites on reducing bond line stress was investigated.
Study and analysis of a tapered shaft in composite materials with variable speed of rotation
Rachid Zahi,Abderahmane Sahli,Djafar Ait Kaci,Fouad Bourada,Abdelouahed Tounsi,Mofareh Hassan Ghazwani 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.2
This paper presents a mechanical model of a “tapered composite shaft” rotating at a constant speed around its axis. The spatial equations of motion are solved using the Lagrange technique, and a finite element approach is employed to construct the model. Theoretical analysis is used to compute the kinetic and strain energies. A comparison is made between conventional finite element methods and hierarchical finite element methods, indicating that the former uses fewer elements and provides higher accuracy in determining natural frequencies. Numerical calculations are performed to determine the eigen frequencies and critical speeds of the rotating composite shaft. The critical speeds of composite shaft systems are compared with existing literature to validate the proposed model.
Abdelmadjid Moulgada,Mohammed El Sallah Zagane,Murat Yaylacı,Ait Kaci Djafar,Sahli Abderahmane,Şevval Öztürk,Ecren Uzun Yaylacı 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.6
The postoperative period for a carrier of total hip prosthesis (THP), especially in the first months, remains the most difficult period for a patient after each operation, even if traumatologist surgeons want the relief and success of their operations. In this investigation, selected three of the daily activities for a wearer of total hip replacement (THR), such as sitting in a chair, lifting a chair, and going downstairs, and was performed a numerical simulation by finite elements based on experimental data by Bergmann (Bergmann 2001) in terms of effort for each activity. Different stresses have been extracted, and a detailed comparison between two activities with different induced stresses such as normal, tensile, and compressive shear stresses.
Ali Benouis,Mohammed El Sallah Zagane,Abdelmadjid Moulgada,Murat Yaylacı,Djafar Ait Kaci,Merve Terzi,Mehmet Emin Özdemir,Ecren Uzun Yaylacı 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.5
This study examines crack behavior within orthopedic cement utilized in total hip replacements through the finite element method. Its main goal is to compute stress intensity factors (SIF) near the crack tip. The analysis encompasses two load types, static and dynamic, applied to a crack starting from the interface between the cement and bone. Specifically, it investigates SIFs under mixed mode conditions during three activities: normal walking, climbing upstairs, and downstairs. The results highlight that a crack originating from a micro-interface under substantial loading can cause cement damage, leading to prosthetic loosening. Stress intensity factors in modes I, II, and III are influenced by the crack tip’s orientation and location in the bone cement, with a 90° orientation yielding notably higher values across all three modes.