The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Bel Abbes Bachir Bouiadjra - One of the best experts on this subject based on the ideXlab platform.

  • elliptical and circular bonded composite repair under mechanical and thermal loading in Aircraft Structures
    Materials Research-ibero-american Journal of Materials, 2014
    Co-Authors: F Benyahia, A Albedah, Bel Abbes Bachir Bouiadjra
    Abstract:

    In this study, the three-dimensional finite element method is used to achieve a comparison between the semi circular and semi elliptical patch repairs in Aircraft Structures. The comparison was done by the analysis of : the mechanical and thermal stress intensity factors (SIF and TSIF) at the tip of repaired crack and the distribution of the adhesive stresses for the two patch shapes. The obtained results show that the semi circular shape of the patch presents lower stress intensity factor at the crack tip, which is beneficial for the fatigue life and lower adhesives stresses, which is beneficial for the repair durability. In addition the circular patch is subjected to less significant thermal residual stresses compared to the elliptical shapes.

  • effect of water absorption on the adhesive damage in bonded composite repair of Aircraft Structures
    Materials & Design, 2014
    Co-Authors: F Benyahia, Bel Abbes Bachir Bouiadjra, A Albedah, Fari M Bouanani, T Achour
    Abstract:

    Abstract In this study, the mechanical properties of the aged adhesive Adekit A140 epoxy were used in a finite element model to evaluate the effect of water absorption on the adhesive damage in bonded composite repair of Aircraft Structures. The damage zone theory was implemented in the finite element code in order to achieve this objective. In addition, the effect of the water absorption, by the adhesive, on the repair efficiency was analyzed by computing the stress intensity factor at the crack tip. The obtained results show that, when the water absorption increases the adhesive loses its rigidity, which reduces the repair durability. Besides, it leads to the increase of the stress intensity factor at the crack tip indicating a reduction in the repair efficiency.

  • analysis of the adhesive damage for different patch shapes in bonded composite repair of Aircraft Structures
    Materials & Design, 2014
    Co-Authors: F Benyahia, A Albedah, Bel Abbes Bachir Bouiadjra
    Abstract:

    Abstract In this study, the adhesive damage in bonded composite repair of Aircraft Structures is analyzed using a three dimensional finite element method. Four different patch shapes were chosen to analyze the adhesive damage: rectangular, trapezoidal, circular and elliptical. The modified damage zone theory was implemented in the FE code to evaluate the adhesive damage. The obtained results show that the rectangular shape is beneficial for the repair durability but it presents a disadvantage for the repair efficiency. The elliptical patch is found the optimal whereas the trapezoidal patch represents the worst shape among the four types analyzed in this paper.

  • analysis of the adhesive failure in bonded composite repair of Aircraft Structures using modified damage zone theory
    Materials & Design, 2013
    Co-Authors: Fari M Bouanani, Bel Abbes Bachir Bouiadjra, F Benyahia, A Albedah, M Belhouari, T Achour
    Abstract:

    Abstract Adhesives play important roles in bonded composite repair as it ensures the transfer of load between the composite patch and the cracked aluminum component. Also, it holds the two Structures together. The damage of the adhesive can thus reduce significantly the efficiency and the durability of the bonded composite repair. The adhesive damage models using critical zone have proven their effectiveness due to simplicity and applicability of the damage criteria in these models. The scope of this study is the estimation of the adhesive damage and failure in bonded composite repair of Aircraft Structures using modified damage zone theory. The effect of this damage on the repair efficiency was analyzed. In order to achieve these objectives, non-linear finite element analyses of adhesive joints considering the material nonlinearity of the adhesive layer were performed. The obtained results show that adhesive damage is principally located at the free edges of the patch and over the crack region. The damage zone ratios depends on the applied load, it affects the repair efficiency when its value approaches the critical value of 0.22.

  • optimisation of the sizes of bonded composite repair in Aircraft Structures
    Materials & Design, 2012
    Co-Authors: S.m. Fekih, Bel Abbes Bachir Bouiadjra, F Benyahia, A Albedah, M Belhouari, A Miloudi
    Abstract:

    Abstract In this study the three-dimensional nonlinear finite element method is used to determine the J integral variation along the front of repaired crack with bonded composite patch in Aircraft Structures. It is known that several parameters influence the repair quality such as the size and the intrinsic properties of the adhesive, the patch and the plate. The experimental design method is used to investigate the effects of patch dimensions (length, width and thickness) in order to achieve an optimisation of the repair operation. This optimisation allows us to determine the most influencing parameters on the repair performances. One can thus help the patch designers to improve the repair quality and durability.

M Belhouari - One of the best experts on this subject based on the ideXlab platform.

  • analysis of the adhesive failure in bonded composite repair of Aircraft Structures using modified damage zone theory
    Materials & Design, 2013
    Co-Authors: Fari M Bouanani, Bel Abbes Bachir Bouiadjra, F Benyahia, A Albedah, M Belhouari, T Achour
    Abstract:

    Abstract Adhesives play important roles in bonded composite repair as it ensures the transfer of load between the composite patch and the cracked aluminum component. Also, it holds the two Structures together. The damage of the adhesive can thus reduce significantly the efficiency and the durability of the bonded composite repair. The adhesive damage models using critical zone have proven their effectiveness due to simplicity and applicability of the damage criteria in these models. The scope of this study is the estimation of the adhesive damage and failure in bonded composite repair of Aircraft Structures using modified damage zone theory. The effect of this damage on the repair efficiency was analyzed. In order to achieve these objectives, non-linear finite element analyses of adhesive joints considering the material nonlinearity of the adhesive layer were performed. The obtained results show that adhesive damage is principally located at the free edges of the patch and over the crack region. The damage zone ratios depends on the applied load, it affects the repair efficiency when its value approaches the critical value of 0.22.

  • optimisation of the sizes of bonded composite repair in Aircraft Structures
    Materials & Design, 2012
    Co-Authors: S.m. Fekih, Bel Abbes Bachir Bouiadjra, F Benyahia, A Albedah, M Belhouari, A Miloudi
    Abstract:

    Abstract In this study the three-dimensional nonlinear finite element method is used to determine the J integral variation along the front of repaired crack with bonded composite patch in Aircraft Structures. It is known that several parameters influence the repair quality such as the size and the intrinsic properties of the adhesive, the patch and the plate. The experimental design method is used to investigate the effects of patch dimensions (length, width and thickness) in order to achieve an optimisation of the repair operation. This optimisation allows us to determine the most influencing parameters on the repair performances. One can thus help the patch designers to improve the repair quality and durability.

  • numerical analysis of the patch shape effects on the performances of bonded composite repair in Aircraft Structures
    Composites Part B-engineering, 2012
    Co-Authors: Mhamdia Rachid, Bel Abbes Bachir Bouiadjra, B Serier, M Belhouari
    Abstract:

    Abstract In this study, the three-dimensional finite element method is used to analyze the effects of the patch shape on the efficiency end the durability of bonded composite repairs of Aircraft Structures. The stress intensity factor at the crack tip is used as fracture criteria. The determination of this factor allows us to estimate the repair efficiency. The analysis of the stresses distribution in the adhesive layer allows us to estimate the durability of the adhesion between the damaged plate and the composite patch. The obtained results show that the repair performances are closely related to the patch shape. It was demonstrated that the rectangular shape of the patch could be improved using an “H” shape of the patch. This last shape could also be improved using an arrow shape.

  • Analysis of the plastic zone size ahead of repaired cracks with bonded composite patch of metallic Aircraft Structures
    Computational Materials Science, 2009
    Co-Authors: Wahid Oudad, S. Touzain, Bel Abbes Bachir Bouiadjra, M Belhouari, Xavier Feaugas
    Abstract:

    In this study, the three-dimensional and non-linear finite element method is used to estimate the performance of the bonded composite repair of metallic Aircraft Structures by analyzing the plastic zone size ahead of repaired cracks. Several calculations have been realized to extract the plasticized elements around the crack tip of repaired crack. The obtained results show that the presence of the composite patch reduces considerably the size of the plastic zone ahead of the crack. The effects of the adhesive properties and the patch thickness on the plastic zone size ahead of repaired cracks were analyzed.

Ashis G Banerjee - One of the best experts on this subject based on the ideXlab platform.

  • a scheduling method for multi robot assembly of Aircraft Structures with soft task precedence constraints
    Robotics and Computer-integrated Manufacturing, 2021
    Co-Authors: Veniamin Tereshchuk, Nikolay Bykov, Samuel Pedigo, Santosh Devasia, Ashis G Banerjee
    Abstract:

    Abstract The use of multiple cooperating robotic manipulators to assemble large Aircraft Structures entails the scheduling of many discrete tasks such as drilling holes and installing fasteners. Since the tasks have different tool requirements, it is desirable to minimize tool changes that incur significant time costs. We approach this problem as a multi-robot task allocation problem with precedence constraints, where the constraints are loosely enforced in terms of prioritizing the tasks to avoid unnecessary tool changes. To avoid the computational burden of searching over all possible task prioritization options, our main contribution is to develop a two-step, data-driven approach to automatically select suitable precedence relations. The first step is to adapt an iterative auction-based method to encode the precedence relations using scheduling heuristics. The second step is to develop a robust machine learning method to generate policies for automatically selecting efficient scheduling heuristics based on the problem characteristics. Experimental results show that the top performing heuristics yield schedules that are more efficient than those of a baseline partition-based scheduler by almost 17%–19%, depending on the robot failure profiles. The learned policies are also able to select heuristics that perform better than greedy selection without incurring additional computational costs.

  • an efficient scheduling algorithm for multi robot task allocation in assembling Aircraft Structures
    International Conference on Robotics and Automation, 2019
    Co-Authors: Veniamin Tereshchuk, John Stewart, Nikolay Bykov, Samuel Pedigo, Santosh Devasia, Ashis G Banerjee
    Abstract:

    Efficient utilization of cooperating robots in the assembly of Aircraft Structures relies on balancing the workload of the robots and ensuring collision-free scheduling. We cast this problem as that of allocating a large number of repetitive assembly tasks, such as drilling holes and installing fasteners, among multiple robots. Such task allocation is often formulated as a traveling salesman problem, which is NP-hard, implying that computing an exactly optimal solution is computationally prohibitive for real-world applications. The problem complexity is further exacerbated by intermittent robot failures necessitating real-time task reallocation. In this letter, we present an efficient method that exploits workpart geometry and problem structure to initially generate balanced and conflict-free robot schedules under nominal conditions. Subsequently, we deal with the failures by allowing the robots to first complete their nominal schedules and then employing a market-based optimizer to allocate the leftover tasks. Results show an improvement of 11.5% in schedule efficiency as compared to an optimized greedy multi-agent scheduler on a four robot system, which is especially promising for Aircraft assembly processes that take many hours to complete. Moreover, the computation times are similar and small, typically hundreds of milliseconds.

Neil Matthews - One of the best experts on this subject based on the ideXlab platform.

  • supersonic particle deposition as a means for enhancing the structural integrity of Aircraft Structures
    International Journal of Fatigue, 2014
    Co-Authors: Lorrie Molent, Neil Matthews, Simon Barter, Dinaz Zenobia Tamboli
    Abstract:

    Abstract The paper presents the results of experimental studies into the application of supersonic particle deposition (SPD) for repairing and enhancing the airworthiness and integrity of aging Aircraft Structures. Presented are the results of coupon tests on the application of SPD doublers to mechanically fastened joints and to simulated corrosion damage tested under constant amplitude fatigue loads. These successful tests are then supported by an application to an F/A-18 Hornet wing attachment centre barrel laboratory test article.

  • on the use of supersonic particle deposition to restore the structural integrity of damaged Aircraft Structures
    International Journal of Fatigue, 2011
    Co-Authors: Neil Matthews, K. Cairns, C A Rodopoulos, Susan Pitt
    Abstract:

    The paper presents a preliminary experimental study and an analysis of the potential application of supersonic particle deposition (SPD) for repairing and restoring the airworthiness and functionality of aging Aircraft Structures. In this work the fatigue performances of cracked metallic Structures with a SPD doubler/patch under constant amplitude loading were monitored using infra-red thermography, whereas for the baseline specimen test the crack length was monitored using digital cameras. In all the cases the experimental data revealed that the baseline specimens, i.e. without an SPD patch, accrued damage more rapidly and that crack growth was significantly greater than the corresponding SPD patched panels. In the majority of tests cases the patched panels showed little evidence of damage/crack growth. A prediction of the fatigue performance of an SPD patched single edge notch coupon is made using SIF values calculated via an approximate analysis and the resultant crack length history is in good agreement with experimental data. Weight function solutions for SPD repairs to centre cracked panels are also developed and validated via three dimensional finite element analysis. The paper concludes that SPD is effective in containing damage and that the proposed analytical solution is good first approximation that can be used to calculate the associated SIF and thereby account for the effect of an SPD patch on crack growth.

Dinaz Zenobia Tamboli - One of the best experts on this subject based on the ideXlab platform.