Experimental and numerical disbond localization analyses of a notched plate repaired with a CFRP patch

Abderahmane, Sahli,Mokhtar, Bouziane M.,Smail, Benbarek,Wayne, Steven F.,Zhang, Liang,Belabbes, Bachir Bouiadjra,Boualem, Serier Techno-Press 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.3

Through the use of finite element analysis and acoustic emission techniques we have evaluated the interfacial failure of a carbon fiber reinforced polymer (CFRP) repair patch on a notched aluminum substrate. The repair of cracks is a very common and widely used practice in the aeronautics field to extend the life of cracked sheet metal panels. The process consists of adhesively bonding a patch that encompasses the notched site to provide additional strength, thereby increasing life and avoiding costly replacements. The mechanical strength of the bonded joint relies mainly on the bonding of the adhesive to the plate and patch stiffness. Stress concentrations at crack tips promote disbonding of the composite patch from the substrate, consequently reducing the bonded area, which makes this a critical aspect of repair effectiveness. In this paper we examine patch disbonding by calculating the influence of notch tip stress on disbond area and verify computational results with acoustic emission (AE) measurements obtained from specimens subjected to uniaxial tension. The FE results showed that disbonding first occurs between the patch and the substrate close to free edge of the patch followed by failure around the tip of the notch, both highest stress regions. Experimental results revealed that cement adhesion at the aluminum interface was the limiting factor in patch performance. The patch did not appear to strengthen the aluminum substrate when measured by stress-strain due to early stage disbonding. Analysis of the AE signals provided insight to the disbond locations and progression at the metal-adhesive interface. Crack growth from the notch in the aluminum was not observed until the stress reached a critical level, an instant before final fracture, which was unaffected by the patch due to early stage disbonding. The FE model was further utilized to study the effects of patch fiber orientation and increased adhesive strength. The model revealed that the effectiveness of patch repairs is strongly dependent upon the combined interactions of adhesive bond strength and fiber orientation.

Experimental and numerical disbond localization analyses of a notched plate repaired with a CFRP patch

Sahli Abderahmane,Bouziane M. Mokhtar,Benbarek Smail,Steven F. Wayne,Liang Zhang,Bachir Bouiadjra Belabbes,Serier Boualem 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.3

Through the use of finite element analysis and acoustic emission techniques we have evaluated the interfacial failure of a carbon fiber reinforced polymer (CFRP) repair patch on a notched aluminum substrate. The repair of cracks is a very common and widely used practice in the aeronautics field to extend the life of cracked sheet metal panels. The process consists of adhesively bonding a patch that encompasses the notched site to provide additional strength, thereby increasing life and avoiding costly replacements. The mechanical strength of the bonded joint relies mainly on the bonding of the adhesive to the plate and patch stiffness. Stress concentrations at crack tips promote disbonding of the composite patch from the substrate, consequently reducing the bonded area, which makes this a critical aspect of repair effectiveness. In this paper we examine patch disbonding by calculating the influence of notch tip stress on disbond area and verify computational results with acoustic emission (AE) measurements obtained from specimens subjected to uniaxial tension. The FE results showed that disbonding first occurs between the patch and the substrate close to free edge of the patch followed by failure around the tip of the notch, both highest stress regions. Experimental results revealed that cement adhesion at the aluminum interface was the limiting factor in patch performance. The patch did not appear to strengthen the aluminum substrate when measured by stress-strain due to early stage disbonding. Analysis of the AE signals provided insight to the disbond locations and progression at the metaladhesive interface. Crack growth from the notch in the aluminum was not observed until the stress reached a critical level, an instant before final fracture, which was unaffected by the patch due to early stage disbonding. The FE model was further utilized to study the effects of patch fiber orientation and increased adhesive strength. The model revealed that the effectiveness of patch repairs is strongly dependent upon the combined interactions of adhesive bond strength and fiber orientation.

Fracture behavior modeling of a 3D crack emanated from bony inclusion in the cement PMMA of total hip replacement

Mohamed, Cherfi,Abderahmane, Sahli,Benbarek, Smail Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

In orthopedic surgery and in particular in total hip arthroplasty, the implant fixation is carried out using a surgical cement called polymethylmethacrylat (PMMA). This cement has to insure a good adhesion between implant and bone and a good load distribution to the bone. By its fragile nature, the cement can easily break when it is subjected to a high stress gradient by presenting a craze zone in the vicinity of inclusion. The focus of this study is to analyze the effect of inclusion in some zone of cement in which the loading condition can lead to the crack opening leading to their propagation and consequently the aseptic loosening of the THR. In this study, the fracture behavior of the bone cement including a strange body (bone remain) from which the onset of a crack is supposed. The effect of loading condition, the geometry, the presence of both crack and inclusion on the stress distribution and the fracture behavior of the cement. Results show that the highest stresses are located around the sharp tip of bony inclusion. Most critical cracks are located in the middle of the cement mantle when they are subjected to one leg standing state loading during walking.

Fracture behavior modeling of a 3D crack emanated from bony inclusion in the cement PMMA of total hip replacement

Cherfi Mohamed,Sahli Abderahmane,Smail Benbarek 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

In orthopedic surgery and in particular in total hip arthroplasty, the implant fixation is carried out using a surgical cement called polymethylmethacrylat (PMMA). This cement has to insure a good adhesion between implant and bone and a good load distribution to the bone. By its fragile nature, the cement can easily break when it is subjected to a high stress gradient by presenting a craze zone in the vicinity of inclusion. The focus of this study is to analyze the effect of inclusion in some zone of cement in which the loading condition can lead to the crack opening leading to their propagation and consequently the aseptic loosening of the THR. In this study, the fracture behavior of the bone cement including a strange body (bone remain) from which the onset of a crack is supposed. The effect of loading condition, the geometry, the presence of both crack and inclusion on the stress distribution and the fracture behavior of the cement. Results show that the highest stresses are located around the sharp tip of bony inclusion. Most critical cracks are located in the middle of the cement mantle when they are subjected to one leg standing state loading during walking.

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.

Numerical simulation of the femur fracture under static loading

Zagane Mohammed El Sallah,Benbarek Smail,Sahli Abderahmane,B. Bachir Bouiadjra,Serier Boualem 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.3

Bone is a living material with a complex hierarchical structure that gives it remarkable mechanical properties. Bone constantly undergoes mechanical. Its quality and resistance to fracture is constantly changing over time through the process of bone remodeling. Numerical modeling allows the study of the bone mechanical behavior and the prediction of different trauma caused by accidents without expose humans to real tests. The aim of this work is the modeling of the femur fracture under static solicitation to create a numerical model to simulate this element fracture. This modeling will contribute to improve the design of the indoor environment to be better safe for the passengers’ transportation means. Results show that vertical loading leads to the femur neck fracture and horizontal loading leads to the fracture of the femur diaphysis. The isotropic consideration of the bone leads to bone fracture by crack propagation but the orthotropic consideration leads to the fragmentation of the bone.

Study of the fracture behavior of different structures by the extended finite element method (X-FEM)

Zagane Mohammed El Sallah,Moulgada Abdelmadjid,Sahli Abderahmane,Baltach Abdelghani,Benouis Ali Techno-Press 2023 Advances in materials research Vol.12 No.4

The fracture mechanics make it possible to characterize the behavior with cracking of structures using parameters quantifiable in the sense of the engineer, in particular the stress field, the size of the crack, and the resistance to cracking of the material. Any structure contains defects, whether they were introduced during the production of the part (machining or molding defects for example). The aim of this work is to determine numerically by the finite element method the stress concentration factor Kt of a plate subjected to a tensile loading containing a lateral form defect with different sizes: a semicircle of different radii, a notch with different opening angles and a crack of different lengths. The crack propagation is then determined using the extended finite element technique (X-FEM). The modeling was carried out using the ABAQUS calculation code.

Comparative study by the finite element method of three activities of a wearer of total hip prosthesis during the postoperative period

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.

The behavior of adhesive joints affected by the geometry and stacking sequence of composite materials

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.