Journal of Reinforced Plastics and Composites, Dec 7, 2009
Bonded composite patch repairs to metallic structures is receiving increased attention in the rec... more 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.
The behaviour of the adhesive bonded joints due to the imposed eccentric loading generates a very... more The behaviour of the adhesive bonded joints due to the imposed eccentric loading generates a very complex distribution of the stress in the structure. Good adhesion between substrate and adhesive ensures a successful and lasting assembly. In this study the finite element method is used to analyze the behaviour of a bonded lap joint of dissimilar materials. The effects of the mechanical properties of the joints on the shear stress variation with and without presence of a circular notch are investigated. The results show that the maximum shear stresses are located at a distance of about 18% that of the lap length whatever the type of material used. In addition, the stress intensity factor is amplified by the presence of the negative effect of disband whose increase is linearly proportional to the square of the stress intensity factor. It reached its maximum value for a crack length equal to two-fifths of the notch radius.
The understanding of the materials fracture requires thorough studies of the phenomena of startin... more The understanding of the materials fracture requires thorough studies of the phenomena of starting and propagation of the cracks which, in general, occur in the strong stress concentrations zones due to the geometrical and/or metallurgical effects [1]. This also makes it possible to explain the phenomenon of fracture starting and to quantify the SIF with respect to the notch geometry and crack length. In this paper an inclusionnotch interaction effect is modelled using the finite element method. The effect of the inter-distance notchinclusion and the rigidity ratio of inclusion-matrix are highlighted with regard to the SIF evolution. The SIF evolution of a crack emanating from a notch inside the inclusion as well as the interaction with the inclusion when the notch is outside is studied. The reduction of the SIF due to the interaction crack-inclusion effect by a patch in composite is also determined.
International Review of Civil Engineering, Mar 31, 2014
The process of repairing structures by composite materials having various advantages. This method... more The process of repairing structures by composite materials having various advantages. This method has received much attention from researchers and engineers. In this study, the finite element method is used to analyze the behaviour of a central crack repaired by bonded boron/epoxy composite patch by computing the stress intensity factor at the crack tip. The effects of mechanical and geometrical properties on the behaviour of the structure are highlighted. The results show that the stress intensity factor at the crack tip repaired by an elliptical patch is reduced to 5 % with regard to the repaired by a circular patch. The reduction obtained by using a boron/epoxy of fibers perpendicular to the crack is more important compared to the same patch having its fibers parallel to the repaired crack. The adhesive properties must be optimised to increase the performance of the patch repair or reinforcement
ABSTRACT Adhesively bonded composite patch repair has been widely used to restore or extend the s... more ABSTRACT Adhesively bonded composite patch repair has been widely used to restore or extend the service life of cracked structural components due to its effectiveness to mechanical repair technique. In this work, the finite element method is applied to analyse the performance of the bonded composite patch for repairing cracks emanating from semicircular notch root in pure mode II. The stress intensity factor was computed at the crack tip repaired using a boron/epoxy patch for different orientation of fibers, taking into account the disbond. In this case, the increase of a patch thickness reduces the negative effects of disbond. When this effect is significant between the patch and the plate, it reduces the repair effectiveness. The maximum reduction obtained by using a boron/epoxy of fibers in the x-direction is of the order of 20% more important compared to a patch having its fibers in the y-direction. The stress intensity factor exhibits an asymptotic behaviour as the disbond size increases.
Dans ce travail, une analyse de la déformation a été réalisée sur des plaques composites hybrides... more Dans ce travail, une analyse de la déformation a été réalisée sur des plaques composites hybrides rectangulaires avec ou sans entaille circulaire à l'aide de la méthode des éléments finis. La résistance à la déformation de la tôle laminée soumise à la compression uniaxiale est mis en évidence en fonction des orientations des fibres. Les résultats montrent que l'augmentation de l'épaisseur de la couche d'aluminium améliore sensiblement la résistance au flambement. Quelle que soit l'orientation de la fissure de la charge critique de flambement reste stable.
In this paper, the evaluation of the SIFof a macrocrack in interaction with one or several microc... more In this paper, the evaluation of the SIFof a macrocrack in interaction with one or several microcracks in a material containing a geometrical defect was investigated. Several configurations were considered in order to apprehend the mechanisms induced by the interaction effect and in particular the effects of reduction and/or amplification of the stress field between macro and single or multiple microcracks. The obtained results show that, macro–microcrack spacing is an important parameter if the microscopic crack is relatively close to the macrocrack-tip. The macrocrack has the tendency to accelerate as it propagates towards the microcrack. When the relative distance characterizing this spacing is higher than 0.3, the interaction effect can be neglected and the SIF remains unchanged for both defect types. When this ratio is lower than 0.3, the interaction between the two defects becomes significant and the stress intensity factor at the macrocrack tip strongly increases.
The technique of repairing or reinforcing cracked metallic structures has been widely used to ext... more The technique of repairing or reinforcing cracked metallic structures has been widely used to extend their service life. In this study, the finite element method is used to analyze the behaviour of a crack repaired by a boron/epoxy patch by computing the stress intensity factor at the crack tip in mode I and mixed mode. The effects of the mechanical
In this study, the crack growth behaviour of an aluminium plate cracked at the tip and repaired w... more 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/d R exceeds 0.8.
Journal of Thermoplastic Composite Materials, Jul 28, 2009
The process of repair of structures by using bonded composite patch is an effective and economica... more The process of repair of structures by using bonded composite patch is an effective and economical method to increase the service life of damaged structures. In this study, the finite element method is used to analyze the behavior of a crack repaired by a circular patch by computing the stress intensity factor (SIF) at the crack tip with and without the disbond. The obtained results show that the boron/epoxy 0° fiber perpendicular to the crack, considerably influences the reduction of the SIF with regard to the boron/epoxy 0° fiber oriented in the parallel direction to the crack. Moreover, the increase of the disbond area amplifies the SIF of the repaired crack and the rate of this increase strongly depends on the disbond area. When the disbond is significant between the patch and the plate, it reduces the repair effectiveness and the crack growth under loading becomes important. The disbond growth results in patch separation.
In this study, a buckling analysis is performed on rectangular composite plates with single and d... more In this study, a buckling analysis is performed on rectangular composite plates with single and double circular notch using the finite element method. Laminated plates of carbon/bismaleimde (IM7/5250-4) are ordered symmetrically as follows [(θ/-θ)2]S. The buckling strength of symmetric laminated plates subjected to uniaxial compression is highlighted as a function of the fibers orientations. The results show that whatever the notch radius, the buckling load is almost stable. Increasing the degree of anisotropy significantly improves critical buckling load.
In this paper, we investigated the crack growth behaviour of cracked thin aluminium plate repaire... more In this paper, we investigated the crack growth behaviour of cracked thin aluminium plate repaired with bonded composite patch. The finite element method is used to study the performance of the bonded composite reinforcement or repair for reducing the stress concentration at a semicircular lateral notch and repairing cracks emanating from this kind of notch. The effects of the adhesive
Adhesively bonded composite patch repair technique has been successfully applied in military airc... more 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.
This paper outlines of the fracture behaviour of discs made of alumina and zircon orthopedic bioc... more This paper outlines of the fracture behaviour of discs made of alumina and zircon orthopedic bioceramics under diametrical compression loading. The finite element method is used to analyze the stress distribution on acetabulum cup of a total hip prosthesis. The elements dimensioning optimization of a bioceramic total hip prosthesis is essential in order to reduce the stress concentration fields. The most loaded area in induced tensile stress causing the fracture is determined. Some results on the evolution of the stress concentration factor and the stress intensity factor of the bifurcated cracks propagating under compression loading in Brazilian discs in mixed mode have been obtained.
Bonded composite repair has been recognized as an efficient and economical method to extend the f... more 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 2c/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.
Journal of Reinforced Plastics and Composites, Dec 7, 2009
Bonded composite patch repairs to metallic structures is receiving increased attention in the rec... more 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.
The behaviour of the adhesive bonded joints due to the imposed eccentric loading generates a very... more The behaviour of the adhesive bonded joints due to the imposed eccentric loading generates a very complex distribution of the stress in the structure. Good adhesion between substrate and adhesive ensures a successful and lasting assembly. In this study the finite element method is used to analyze the behaviour of a bonded lap joint of dissimilar materials. The effects of the mechanical properties of the joints on the shear stress variation with and without presence of a circular notch are investigated. The results show that the maximum shear stresses are located at a distance of about 18% that of the lap length whatever the type of material used. In addition, the stress intensity factor is amplified by the presence of the negative effect of disband whose increase is linearly proportional to the square of the stress intensity factor. It reached its maximum value for a crack length equal to two-fifths of the notch radius.
The understanding of the materials fracture requires thorough studies of the phenomena of startin... more The understanding of the materials fracture requires thorough studies of the phenomena of starting and propagation of the cracks which, in general, occur in the strong stress concentrations zones due to the geometrical and/or metallurgical effects [1]. This also makes it possible to explain the phenomenon of fracture starting and to quantify the SIF with respect to the notch geometry and crack length. In this paper an inclusionnotch interaction effect is modelled using the finite element method. The effect of the inter-distance notchinclusion and the rigidity ratio of inclusion-matrix are highlighted with regard to the SIF evolution. The SIF evolution of a crack emanating from a notch inside the inclusion as well as the interaction with the inclusion when the notch is outside is studied. The reduction of the SIF due to the interaction crack-inclusion effect by a patch in composite is also determined.
International Review of Civil Engineering, Mar 31, 2014
The process of repairing structures by composite materials having various advantages. This method... more The process of repairing structures by composite materials having various advantages. This method has received much attention from researchers and engineers. In this study, the finite element method is used to analyze the behaviour of a central crack repaired by bonded boron/epoxy composite patch by computing the stress intensity factor at the crack tip. The effects of mechanical and geometrical properties on the behaviour of the structure are highlighted. The results show that the stress intensity factor at the crack tip repaired by an elliptical patch is reduced to 5 % with regard to the repaired by a circular patch. The reduction obtained by using a boron/epoxy of fibers perpendicular to the crack is more important compared to the same patch having its fibers parallel to the repaired crack. The adhesive properties must be optimised to increase the performance of the patch repair or reinforcement
ABSTRACT Adhesively bonded composite patch repair has been widely used to restore or extend the s... more ABSTRACT Adhesively bonded composite patch repair has been widely used to restore or extend the service life of cracked structural components due to its effectiveness to mechanical repair technique. In this work, the finite element method is applied to analyse the performance of the bonded composite patch for repairing cracks emanating from semicircular notch root in pure mode II. The stress intensity factor was computed at the crack tip repaired using a boron/epoxy patch for different orientation of fibers, taking into account the disbond. In this case, the increase of a patch thickness reduces the negative effects of disbond. When this effect is significant between the patch and the plate, it reduces the repair effectiveness. The maximum reduction obtained by using a boron/epoxy of fibers in the x-direction is of the order of 20% more important compared to a patch having its fibers in the y-direction. The stress intensity factor exhibits an asymptotic behaviour as the disbond size increases.
Dans ce travail, une analyse de la déformation a été réalisée sur des plaques composites hybrides... more Dans ce travail, une analyse de la déformation a été réalisée sur des plaques composites hybrides rectangulaires avec ou sans entaille circulaire à l'aide de la méthode des éléments finis. La résistance à la déformation de la tôle laminée soumise à la compression uniaxiale est mis en évidence en fonction des orientations des fibres. Les résultats montrent que l'augmentation de l'épaisseur de la couche d'aluminium améliore sensiblement la résistance au flambement. Quelle que soit l'orientation de la fissure de la charge critique de flambement reste stable.
In this paper, the evaluation of the SIFof a macrocrack in interaction with one or several microc... more In this paper, the evaluation of the SIFof a macrocrack in interaction with one or several microcracks in a material containing a geometrical defect was investigated. Several configurations were considered in order to apprehend the mechanisms induced by the interaction effect and in particular the effects of reduction and/or amplification of the stress field between macro and single or multiple microcracks. The obtained results show that, macro–microcrack spacing is an important parameter if the microscopic crack is relatively close to the macrocrack-tip. The macrocrack has the tendency to accelerate as it propagates towards the microcrack. When the relative distance characterizing this spacing is higher than 0.3, the interaction effect can be neglected and the SIF remains unchanged for both defect types. When this ratio is lower than 0.3, the interaction between the two defects becomes significant and the stress intensity factor at the macrocrack tip strongly increases.
The technique of repairing or reinforcing cracked metallic structures has been widely used to ext... more The technique of repairing or reinforcing cracked metallic structures has been widely used to extend their service life. In this study, the finite element method is used to analyze the behaviour of a crack repaired by a boron/epoxy patch by computing the stress intensity factor at the crack tip in mode I and mixed mode. The effects of the mechanical
In this study, the crack growth behaviour of an aluminium plate cracked at the tip and repaired w... more 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/d R exceeds 0.8.
Journal of Thermoplastic Composite Materials, Jul 28, 2009
The process of repair of structures by using bonded composite patch is an effective and economica... more The process of repair of structures by using bonded composite patch is an effective and economical method to increase the service life of damaged structures. In this study, the finite element method is used to analyze the behavior of a crack repaired by a circular patch by computing the stress intensity factor (SIF) at the crack tip with and without the disbond. The obtained results show that the boron/epoxy 0° fiber perpendicular to the crack, considerably influences the reduction of the SIF with regard to the boron/epoxy 0° fiber oriented in the parallel direction to the crack. Moreover, the increase of the disbond area amplifies the SIF of the repaired crack and the rate of this increase strongly depends on the disbond area. When the disbond is significant between the patch and the plate, it reduces the repair effectiveness and the crack growth under loading becomes important. The disbond growth results in patch separation.
In this study, a buckling analysis is performed on rectangular composite plates with single and d... more In this study, a buckling analysis is performed on rectangular composite plates with single and double circular notch using the finite element method. Laminated plates of carbon/bismaleimde (IM7/5250-4) are ordered symmetrically as follows [(θ/-θ)2]S. The buckling strength of symmetric laminated plates subjected to uniaxial compression is highlighted as a function of the fibers orientations. The results show that whatever the notch radius, the buckling load is almost stable. Increasing the degree of anisotropy significantly improves critical buckling load.
In this paper, we investigated the crack growth behaviour of cracked thin aluminium plate repaire... more In this paper, we investigated the crack growth behaviour of cracked thin aluminium plate repaired with bonded composite patch. The finite element method is used to study the performance of the bonded composite reinforcement or repair for reducing the stress concentration at a semicircular lateral notch and repairing cracks emanating from this kind of notch. The effects of the adhesive
Adhesively bonded composite patch repair technique has been successfully applied in military airc... more 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.
This paper outlines of the fracture behaviour of discs made of alumina and zircon orthopedic bioc... more This paper outlines of the fracture behaviour of discs made of alumina and zircon orthopedic bioceramics under diametrical compression loading. The finite element method is used to analyze the stress distribution on acetabulum cup of a total hip prosthesis. The elements dimensioning optimization of a bioceramic total hip prosthesis is essential in order to reduce the stress concentration fields. The most loaded area in induced tensile stress causing the fracture is determined. Some results on the evolution of the stress concentration factor and the stress intensity factor of the bifurcated cracks propagating under compression loading in Brazilian discs in mixed mode have been obtained.
Bonded composite repair has been recognized as an efficient and economical method to extend the f... more 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 2c/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.
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