The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform

Djamel Ouinas - One of the best experts on this subject based on the ideXlab platform.

  • Progressive edge cracked aluminium plate repaired with adhesively bonded composite patch under full width disbond
    Composites Part B-engineering, 2012
    Co-Authors: Djamel Ouinas, Bel Abbes Bachir Bouiadjra, S. Himouri, Nouredine Benderdouche
    Abstract:

    Abstract In this study, the crack growth behaviour of an aluminium plate cracked at the tip and repaired with a bonded Boron/Epoxy composite patch in the case of full-width disbond was investigated. This effect is the imperfection which could result during the bonded patch of the repaired structure. Disbonds of various sizes and situated at different positions with respect to the crack tip as well as the effect of adhesive and patch thickness on repair performance were examined. An analysis procedure involving the efficient finite element modelling applied to cracked plate, adhesive and composite patch was used to compute the stress intensity factors. The crack growth rate is dominated by the stress intensity factor near the location and size of the pre-existing disbonds. The cracked plate and disbond propagation result in an increase in the patch deformation. The patch does not have an influence on the crack growth when the ratio 2a/dR exceeds 0.8.

  • effect of disbonding between a composite patch and a cracked aluminum plate on the stress intensity factor
    Journal of Reinforced Plastics and Composites, 2010
    Co-Authors: Djamel Ouinas
    Abstract:

    Bonded composite patch repairs to metallic structures is receiving increased attention in the recent years. It offers various advantages over rivetted doubler, particularly for airframe repairs. This article presents the crack growth behavior of an edge cracked aluminum plate repaired using Boron/Epoxy composite patch. The effect of the size and location of this disbond on the tensile behavior of the repaired plate is investigated. An analysis procedure, involving finite element modeling of the cracked plate, adhesive, and composite patch, is conducted to compute the stress intensity factor. The results indicate that the crack growth rate is dominated by the stress intensity factor and the size of the pre-existing disbonds. Cracking of the plate and propagation of the disbond results in an increase in the patch deformation.

  • modelling of a cracked aluminium plate repaired with composite octagonal patch in mode i and mixed mode
    Materials & Design, 2009
    Co-Authors: Djamel Ouinas, Bel Abbes Bachir Bouiadjra, Belkacem Achour, Nouredine Benderdouche
    Abstract:

    Abstract Adhesively bonded composite patch repair technique has been successfully applied in military aircraft repair and has recently been expanded to commercial aircraft industry. This technique is applied to extend the service life of cracked aluminium components. In this paper, the finite element method is applied to analyse the central crack’s behaviour repaired by a Boron/Epoxy composite patch. The effects of the mechanical and geometrical properties of the patch on the variation of the stress intensity factor at the crack tip were highlighted. The obtained results show that the stress intensity factor at the crack tip, repaired by an octagonal patch of height 2c/3, is reduced by 5% with regard to the one repaired by an octagonal patch of size ‘c’. For a height patch of c/3 the reduction is about 7%. The maximum reduction of composite patch of fibres in y-direction is about 30% compared to the aluminium patch. This reduction doubles when a composite patch of fibres in x-direction is used. The adhesive properties must be optimised to increase the performance of the repair of structures by such reinforcement.

  • fe analysis of the behaviour of octagonal bonded composite repair in aircraft structures
    Computational Materials Science, 2008
    Co-Authors: K Kaddouri, Djamel Ouinas, Bel Abbes Bachir Bouiadjra
    Abstract:

    Abstract Bonded composite repair has been recognized as an efficient and economical method to extend the fatigue life of cracked aluminium components. In this work, the finite element method is applied to analyze the central crack’s behaviour repaired by a Boron/Epoxy composite patch. The knowledge of the stress distribution in the neighbourhood of cracks has an importance for the analysis of their repair according to the patch geometry. The effects of mechanical and geometrical properties of the patch on the variation of the stress intensity factor at the crack tip were highlighted. The obtained results show that the stress intensity factor at the repaired crack with composite patch of height 2 c /3 is reduced about 5% compared to cracks repaired with octagonal patch of size c . For patch height of c /3 the reduction is about 7%. The adhesive properties must be optimised in order to increase the repair performances and to avoid the adhesive failure.

  • comparison of the effectiveness of Boron Epoxy and graphite Epoxy patches for repaired cracks emanating from a semicircular notch edge
    Composite Structures, 2007
    Co-Authors: Djamel Ouinas, Bel Abbes Bachir Bouiadjra, Boualem Serier, M Saidbekkouche
    Abstract:

    The adhesively bonded composite patch repair technique has been used to restore or extend the service life of the cracked aluminium structural components because of its efficiency. In this study, the finite element method is used to analyse the performance of the different bonded composite patches at a semicircular lateral notch and the repair of cracks emanating from this kind of notch. The knowledge of the stress distribution in the neighbourhood of the cracks is important for the analysis of their repair according to the geometry of the patch. The effects of the mechanical and geometrical properties on the variation of the stress intensity factor in the crack tip were highlighted. The effects of the adhesive properties and of the patch size on the stress intensity factor variation at the crack tip in mode I were also highlighted. The comparison between the double and single patch repairs is also given in this study. The results obtained show that the stress intensity factor of the crack tip repaired by two composite patches, is reduced to a half compared to the one that is repaired only by one patch. The orientation of fibres possessing a higher rigidity perpendicularly to the crack propagation considerably influences the reduction of the stress intensity factor. The adhesive properties must be optimised in order to increase the performance of the patch repair or the reinforcement.

Lili Tong - One of the best experts on this subject based on the ideXlab platform.

  • multi objective design optimization of composite submerged cylindrical pressure hull for minimum buoyancy factor and maximum buckling load capacity
    Defence Technology, 2020
    Co-Authors: Muhammad Imran, Hafiz Muhammad Waqas, Ahsan Elahi, Lili Tong, Muqeem Uddin
    Abstract:

    Abstract This paper presents the design optimization of composite submersible cylindrical pressure hull subjected to 3 MPa hydrostatic pressure. The design optimization study is conducted for cross-ply layups [0s/90t/0u], [0s/90t/0u]s, [0s/90t]s and [90s/0t]s considering three uni-directional composites, i.e. Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy. The optimization study is performed by coupling a Multi-Objective Genetic Algorithm (MOGA) and Analytical Analysis. Minimizing the buoyancy factor and maximizing the buckling load factor are considered as the objectives of the optimization study. The objectives of the optimization are achieved under constraints on the Tsai-Wu, Tsai-Hill and Maximum stress composite failure criteria and on buckling load factor. To verify the optimization approach, optimization of one particular layup configuration is also conducted in ANSYS with the same objectives and constraints.

  • design optimization and non linear buckling analysis of spherical composite submersible pressure hull
    Materials, 2020
    Co-Authors: Muhammad Imran, Hafiz Muhammad Waqas, Muqeem Uddin, Lili Tong, Riaz Muhammad, Asghar Khan
    Abstract:

    This paper describes an optimization study of a spherical composite submersible pressure hull employing a genetic algorithm (GA) in ANSYS. A total of five lay-up arrangements were optimized for three unidirectional composites carbon/Epoxy, glass/Epoxy, and Boron/Epoxy. The minimization of the buoyancy factor ( B . F ) was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor ( λ ) were used as the material failure and instability constraints. To determine the effect of geometric non-linearity and imperfections on the optimized design, a non-linear buckling analysis was also carried out for one selected optimized design in ABAQUS. The non-linear buckling analysis was carried out using the modified RIKS procedure, in which the imperfection size changed from 1 to 10 mm. A maximum decrease of 65.937% in buoyancy factor ( B . F ) over an equivalent spherical steel pressure hull was computed for carbon/Epoxy. Moreover, carbon/Epoxy displayed larger decreases in buoyancy factor ( B . F ) in the case of 4 out of a total of 5 lay-up arrangements. The collapse depth decreased from 517.95 m to 412.596 m for a 5 mm lowest mode imperfection. Similarly, the collapse depth decreased from 522.39 m to 315.6018 for a 5 mm worst mode imperfection.

  • design optimization of composite submerged cylindrical pressure hull using genetic algorithm and finite element analysis
    Ocean Engineering, 2019
    Co-Authors: Muhammad Imran, Lili Tong, Hafiz Muhammad Waqas
    Abstract:

    Abstract The design of structures made of laminated composites greatly depends on the fiber orientation angle and the number of ply layers. In the present study design optimization of composite submerged pressure hull under 3 MPa hydrostatic pressure, which corresponds to 300 m depth, is carried out. The number of layers and orientation angles are optimized for layups [0m/90n/0o], [10m/-10n/90o/-10p/10q], [α1m/α2n], [α1m/α2n/α3o] and [α1m/α2n/α3o/α4p/α5q] using three unidirectional composite materials, Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy. The optimization process is carried out in ANSYS Workbench using a Genetic Algorithm. Minimizing the buoyancy factor is used as the objective function of the optimization. The constraints on the optimization process are Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor. Optimization study is also conducted for one selected layup configuration using ABAQUS and ISIGHT. Additionally, a sensitivity analysis is also carried out to study the effect of various design parameters on the optimum design of composite submerged pressure hull.

  • design optimization of lay up and composite material system to achieve minimum buoyancy factor for composite elliptical submersible pressure hull
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Lili Tong, Hui Qi, Mahmoud Helal
    Abstract:

    The design of laminated composite structures is very susceptible to changes in angle of fiber orientation and ply thickness. In the present work, different lay-up sequences for laminates including, cross-ply [0m/90n]s, [90m/0n]s and angle-ply [0m/±αn]s, [90m/±αn]s, [±α]ns, are analyzed. The lay-up sequence, orientation and ply number are optimized using three composite materials T700/Epoxy composites, T300/Graphite/Epoxy and B(4)/5505 Boron/Epoxy. Minimize the buoyancy factor of the submersible pressure hull is considered as the objective function. The constraints based on the failure strength and the buckling strength of the pressure hull, incorporating both the Tsai–Wu and the maximum stress failure criteria. The finite element analysis and the optimization process are performed using ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the optimal structural strength design.

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

  • Progressive edge cracked aluminium plate repaired with adhesively bonded composite patch under full width disbond
    Composites Part B-engineering, 2012
    Co-Authors: Djamel Ouinas, Bel Abbes Bachir Bouiadjra, S. Himouri, Nouredine Benderdouche
    Abstract:

    Abstract In this study, the crack growth behaviour of an aluminium plate cracked at the tip and repaired with a bonded Boron/Epoxy composite patch in the case of full-width disbond was investigated. This effect is the imperfection which could result during the bonded patch of the repaired structure. Disbonds of various sizes and situated at different positions with respect to the crack tip as well as the effect of adhesive and patch thickness on repair performance were examined. An analysis procedure involving the efficient finite element modelling applied to cracked plate, adhesive and composite patch was used to compute the stress intensity factors. The crack growth rate is dominated by the stress intensity factor near the location and size of the pre-existing disbonds. The cracked plate and disbond propagation result in an increase in the patch deformation. The patch does not have an influence on the crack growth when the ratio 2a/dR exceeds 0.8.

  • modelling of a cracked aluminium plate repaired with composite octagonal patch in mode i and mixed mode
    Materials & Design, 2009
    Co-Authors: Djamel Ouinas, Bel Abbes Bachir Bouiadjra, Belkacem Achour, Nouredine Benderdouche
    Abstract:

    Abstract Adhesively bonded composite patch repair technique has been successfully applied in military aircraft repair and has recently been expanded to commercial aircraft industry. This technique is applied to extend the service life of cracked aluminium components. In this paper, the finite element method is applied to analyse the central crack’s behaviour repaired by a Boron/Epoxy composite patch. The effects of the mechanical and geometrical properties of the patch on the variation of the stress intensity factor at the crack tip were highlighted. The obtained results show that the stress intensity factor at the crack tip, repaired by an octagonal patch of height 2c/3, is reduced by 5% with regard to the one repaired by an octagonal patch of size ‘c’. For a height patch of c/3 the reduction is about 7%. The maximum reduction of composite patch of fibres in y-direction is about 30% compared to the aluminium patch. This reduction doubles when a composite patch of fibres in x-direction is used. The adhesive properties must be optimised to increase the performance of the repair of structures by such reinforcement.

  • fe analysis of the behaviour of octagonal bonded composite repair in aircraft structures
    Computational Materials Science, 2008
    Co-Authors: K Kaddouri, Djamel Ouinas, Bel Abbes Bachir Bouiadjra
    Abstract:

    Abstract Bonded composite repair has been recognized as an efficient and economical method to extend the fatigue life of cracked aluminium components. In this work, the finite element method is applied to analyze the central crack’s behaviour repaired by a Boron/Epoxy composite patch. The knowledge of the stress distribution in the neighbourhood of cracks has an importance for the analysis of their repair according to the patch geometry. The effects of mechanical and geometrical properties of the patch on the variation of the stress intensity factor at the crack tip were highlighted. The obtained results show that the stress intensity factor at the repaired crack with composite patch of height 2 c /3 is reduced about 5% compared to cracks repaired with octagonal patch of size c . For patch height of c /3 the reduction is about 7%. The adhesive properties must be optimised in order to increase the repair performances and to avoid the adhesive failure.

  • comparison of the effectiveness of Boron Epoxy and graphite Epoxy patches for repaired cracks emanating from a semicircular notch edge
    Composite Structures, 2007
    Co-Authors: Djamel Ouinas, Bel Abbes Bachir Bouiadjra, Boualem Serier, M Saidbekkouche
    Abstract:

    The adhesively bonded composite patch repair technique has been used to restore or extend the service life of the cracked aluminium structural components because of its efficiency. In this study, the finite element method is used to analyse the performance of the different bonded composite patches at a semicircular lateral notch and the repair of cracks emanating from this kind of notch. The knowledge of the stress distribution in the neighbourhood of the cracks is important for the analysis of their repair according to the geometry of the patch. The effects of the mechanical and geometrical properties on the variation of the stress intensity factor in the crack tip were highlighted. The effects of the adhesive properties and of the patch size on the stress intensity factor variation at the crack tip in mode I were also highlighted. The comparison between the double and single patch repairs is also given in this study. The results obtained show that the stress intensity factor of the crack tip repaired by two composite patches, is reduced to a half compared to the one that is repaired only by one patch. The orientation of fibres possessing a higher rigidity perpendicularly to the crack propagation considerably influences the reduction of the stress intensity factor. The adhesive properties must be optimised in order to increase the performance of the patch repair or the reinforcement.

  • The effects of disbonds on the stress intensity factor of aluminium panels repaired using composite materials
    Composite Structures, 2007
    Co-Authors: Djamel Ouinas, Bel Abbes Bachir Bouiadjra, Boualem Serier
    Abstract:

    Abstract Bonded composite patching has been recognized as an efficient and economical method to extend the service life of cracked aluminum components. The stress intensity factor is considerably reduced by the bonded composite repair. In this work, the finite element method is applied to analyse the behavior crack emanating from semi-circular notch root repaired by a Boron/Epoxy composite patch. The stress intensity factor (SIF) was computed for cracks repaired using a composite patch, taking into account of the disbond. In this case, the increase of patch thickness reduce the negative effects of disbond. The maximal reduction of composite patch of orientation (1) is the order of 56% more important with regard to patch of orientation (2) . The minimal SIF in the presence of the disbond is obtained when the crack length is the order of 2 ρ ent . It reaches its value maximal for a crack length equal to 2 ρ ent /5.

Muhammad Imran - One of the best experts on this subject based on the ideXlab platform.

  • multi objective design optimization of composite submerged cylindrical pressure hull for minimum buoyancy factor and maximum buckling load capacity
    Defence Technology, 2020
    Co-Authors: Muhammad Imran, Hafiz Muhammad Waqas, Ahsan Elahi, Lili Tong, Muqeem Uddin
    Abstract:

    Abstract This paper presents the design optimization of composite submersible cylindrical pressure hull subjected to 3 MPa hydrostatic pressure. The design optimization study is conducted for cross-ply layups [0s/90t/0u], [0s/90t/0u]s, [0s/90t]s and [90s/0t]s considering three uni-directional composites, i.e. Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy. The optimization study is performed by coupling a Multi-Objective Genetic Algorithm (MOGA) and Analytical Analysis. Minimizing the buoyancy factor and maximizing the buckling load factor are considered as the objectives of the optimization study. The objectives of the optimization are achieved under constraints on the Tsai-Wu, Tsai-Hill and Maximum stress composite failure criteria and on buckling load factor. To verify the optimization approach, optimization of one particular layup configuration is also conducted in ANSYS with the same objectives and constraints.

  • design optimization and non linear buckling analysis of spherical composite submersible pressure hull
    Materials, 2020
    Co-Authors: Muhammad Imran, Hafiz Muhammad Waqas, Muqeem Uddin, Lili Tong, Riaz Muhammad, Asghar Khan
    Abstract:

    This paper describes an optimization study of a spherical composite submersible pressure hull employing a genetic algorithm (GA) in ANSYS. A total of five lay-up arrangements were optimized for three unidirectional composites carbon/Epoxy, glass/Epoxy, and Boron/Epoxy. The minimization of the buoyancy factor ( B . F ) was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor ( λ ) were used as the material failure and instability constraints. To determine the effect of geometric non-linearity and imperfections on the optimized design, a non-linear buckling analysis was also carried out for one selected optimized design in ABAQUS. The non-linear buckling analysis was carried out using the modified RIKS procedure, in which the imperfection size changed from 1 to 10 mm. A maximum decrease of 65.937% in buoyancy factor ( B . F ) over an equivalent spherical steel pressure hull was computed for carbon/Epoxy. Moreover, carbon/Epoxy displayed larger decreases in buoyancy factor ( B . F ) in the case of 4 out of a total of 5 lay-up arrangements. The collapse depth decreased from 517.95 m to 412.596 m for a 5 mm lowest mode imperfection. Similarly, the collapse depth decreased from 522.39 m to 315.6018 for a 5 mm worst mode imperfection.

  • design optimization of composite submerged cylindrical pressure hull using genetic algorithm and finite element analysis
    Ocean Engineering, 2019
    Co-Authors: Muhammad Imran, Lili Tong, Hafiz Muhammad Waqas
    Abstract:

    Abstract The design of structures made of laminated composites greatly depends on the fiber orientation angle and the number of ply layers. In the present study design optimization of composite submerged pressure hull under 3 MPa hydrostatic pressure, which corresponds to 300 m depth, is carried out. The number of layers and orientation angles are optimized for layups [0m/90n/0o], [10m/-10n/90o/-10p/10q], [α1m/α2n], [α1m/α2n/α3o] and [α1m/α2n/α3o/α4p/α5q] using three unidirectional composite materials, Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy. The optimization process is carried out in ANSYS Workbench using a Genetic Algorithm. Minimizing the buoyancy factor is used as the objective function of the optimization. The constraints on the optimization process are Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor. Optimization study is also conducted for one selected layup configuration using ABAQUS and ISIGHT. Additionally, a sensitivity analysis is also carried out to study the effect of various design parameters on the optimum design of composite submerged pressure hull.

Mahmoud Helal - One of the best experts on this subject based on the ideXlab platform.

  • design optimization of lay up and composite material system to achieve minimum buoyancy factor for composite elliptical submersible pressure hull
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Lili Tong, Hui Qi, Mahmoud Helal
    Abstract:

    The design of laminated composite structures is very susceptible to changes in angle of fiber orientation and ply thickness. In the present work, different lay-up sequences for laminates including, cross-ply [0m/90n]s, [90m/0n]s and angle-ply [0m/±αn]s, [90m/±αn]s, [±α]ns, are analyzed. The lay-up sequence, orientation and ply number are optimized using three composite materials T700/Epoxy composites, T300/Graphite/Epoxy and B(4)/5505 Boron/Epoxy. Minimize the buoyancy factor of the submersible pressure hull is considered as the objective function. The constraints based on the failure strength and the buckling strength of the pressure hull, incorporating both the Tsai–Wu and the maximum stress failure criteria. The finite element analysis and the optimization process are performed using ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the optimal structural strength design.