The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Brian Egan - One of the best experts on this subject based on the ideXlab platform.
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bearing damage characteristics of fibre reinforced countersunk composite bolted joints subjected to quasi static shear loading
Composite Structures, 2017Co-Authors: Hamed Yazdani Nezhad, Brian Egan, Fiachra Merwick, C T MccarthyAbstract:This paper studies the progression of damage in carbon fibre-reinforced polymer (CFRP) countersunk composite bolted joints (CBJs) with neat-fit clearance, subjected to quasi-static loading. Damage mechanisms, comprising of fibre buckling and breakage, matrix damage, shear damage and inter-laminar delamination within the CFRP composite parts of the joints have been studied. Load-displacement curves, X-ray and optical microscopic images in single- and three-bolt CBJs were used to investigate damage and deformation characteristics. The observations were then employed to further investigate the type of failure and the extent of damage. The evolution of damage within the composite parts was correlated to the failure characteristics of the joints: It was found that the type and extension of damage is strongly correlated with the ultimate failure load point of the joint in single-bolt CBJs. A combined inter/intra-laminar damage consisting of fibre cluster breakage, extensive fibre buckling, debonding and delamination was observed at the ultimate failure load. This study was then extended to three-bolt CBJ where damage surrounding each bolt and its corresponding failure load was strongly correlated: The final study showed that the ultimate failure point in single-bolt CBJ and the first-bolt-failure point in three-bolt CBJ correspond to the composite plies undergoing intra-laminar damage with the size reaching to the edge of the countersunk head. This damage developed extensively through the thickness of the composite parts underneath the Countersink, and in the direction opposite to the loading direction. Outside the countersunk head, debonding and delamination were found to be the dominant damage driving mechanisms. Finally, a new design rule has been proposed to predict the response of multi-bolt joints (damage area and failure load) by using the response in single-bolt CBJ as an initial baseline.
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finite element analysis of catastrophic failure of dynamically loaded countersunk composite fuselage joints
Composite Structures, 2015Co-Authors: Brian Egan, R M Frizzell, M A Mccarthy, C T MccarthyAbstract:Abstract Accurate models of dynamic structural failure are important for crashworthiness studies. To date, catastrophic failure of dynamically-loaded composite bolted joints has been studied using global or stacked shell element models. In this paper, high-fidelity (three-dimensional solid) explicit FE models are used to simulate catastrophic failure of countersunk composite fuselage joints. While current state-of-the-art 3D modelling approaches focus almost exclusively on the prediction of composite damage, this study also investigates the treatment of fastener damage. Fastener fracture is a common catastrophic joint failure mode, particularly in joints designed to initially fail in bearing. A Johnson–Cook material model and cohesive elements were used to predict plasticity, damage and fracture of the titanium (Ti–6Al–4V) fastener. Although a model calibration was required, due to the complex interaction of model parameters, numerical results demonstrate key trends of experiments and provide a starting point for the development of more predictive approaches for simulating fastener failure.
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Modelling bearing failure in countersunk composite joints under quasi-static loading using 3D explicit finite element analysis
Composite Structures, 2014Co-Authors: Brian Egan, R M Frizzell, Michael A. Mccarthy, P.j. Gray, Conor T. MccarthyAbstract:Abstract Three-dimensional explicit finite element modelling is used to predict the quasi-static bearing response of typical countersunk composite fuselage skin joints. In order to accurately simulate bearing failure, a user-defined 3D composite damage model was formulated for Abaqus/Explicit and included Puck failure criteria, a nonlinear shear law and a crack band model to mitigate mesh sensitivity. A novel approach was developed to employ characteristic element lengths which account for the orientation of composite ply cracks in the Abaqus/Explicit solver. Resulting models accurately predicted initial joint sticking behaviour and the elastic loading response of single-bolt and three-bolt joints, but preliminary predictions of bearing failure onset were overly-conservative. Improved failure predictions were obtained by utilising a fracture energy for compressive fibre failure which was considered more relevant for simulating bearing damage. The explicit models were exceptionally robust, showing capability to predict extensive hole crushing. Methods of dramatically improving joint model efficiency were highlighted.
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Static and high-rate loading of single and multi-bolt carbon-epoxy aircraft fuselage joints
Composites Part A-applied Science and Manufacturing, 2013Co-Authors: Brian Egan, Conor T. Mccarthy, Michael A. Mccarthy, P.j. Gray, Ronan M. O'higginsAbstract:Abstract Single-lap shear behaviour of carbon–epoxy composite bolted aircraft fuselage joints at quasi-static and dynamic (5 m/s and 10 m/s) loading speeds is studied experimentally. Single and multi-bolt joints with countersunk fasteners were tested. The initial joint failure mode was bearing, while final failure was either due to fastener pull-through or fastener fracture at a thread. Much less hole bearing damage, and hence energy absorption, occurred when the fastener(s) fractured at a thread, which occurred most frequently in thick joints and in quasi-static tests. Fastener failure thus requires special consideration in designing crashworthy fastened composite structures; if it can be delayed, energy absorption is greater. A correlation between energy absorption in multi-bolt and single-bolt joint tests indicates potential to downsize future test programmes. Tapering a thin fuselage panel layup to a thicker layup at the countersunk hole proved highly effective in achieving satisfactory joint strength and energy absorption.
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modelling a single bolt countersunk composite joint using implicit and explicit finite element analysis
Computational Materials Science, 2012Co-Authors: Brian Egan, C T Mccarthy, M A Mccarthy, P.j. Gray, R M FrizzellAbstract:Abstract In this paper the mechanical behaviour of a composite joint incorporating a single countersunk fastener is investigated both experimentally and numerically. Results from an explicit dynamics model are compared to those obtained from an implicit modelling approach and measurements from experimental tests. The explicit dynamics method is of interest due to its robust contact modelling, and the scalability of the procedure for application to large structures. The deformation of the joint models in the overlap region is verified experimentally using extensometers. Experimental measures of secondary bending, obtained using 3D digital image correlation (DIC), provide good agreement with the numerical results.
C T Mccarthy - One of the best experts on this subject based on the ideXlab platform.
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bearing damage characteristics of fibre reinforced countersunk composite bolted joints subjected to quasi static shear loading
Composite Structures, 2017Co-Authors: Hamed Yazdani Nezhad, Brian Egan, Fiachra Merwick, C T MccarthyAbstract:This paper studies the progression of damage in carbon fibre-reinforced polymer (CFRP) countersunk composite bolted joints (CBJs) with neat-fit clearance, subjected to quasi-static loading. Damage mechanisms, comprising of fibre buckling and breakage, matrix damage, shear damage and inter-laminar delamination within the CFRP composite parts of the joints have been studied. Load-displacement curves, X-ray and optical microscopic images in single- and three-bolt CBJs were used to investigate damage and deformation characteristics. The observations were then employed to further investigate the type of failure and the extent of damage. The evolution of damage within the composite parts was correlated to the failure characteristics of the joints: It was found that the type and extension of damage is strongly correlated with the ultimate failure load point of the joint in single-bolt CBJs. A combined inter/intra-laminar damage consisting of fibre cluster breakage, extensive fibre buckling, debonding and delamination was observed at the ultimate failure load. This study was then extended to three-bolt CBJ where damage surrounding each bolt and its corresponding failure load was strongly correlated: The final study showed that the ultimate failure point in single-bolt CBJ and the first-bolt-failure point in three-bolt CBJ correspond to the composite plies undergoing intra-laminar damage with the size reaching to the edge of the countersunk head. This damage developed extensively through the thickness of the composite parts underneath the Countersink, and in the direction opposite to the loading direction. Outside the countersunk head, debonding and delamination were found to be the dominant damage driving mechanisms. Finally, a new design rule has been proposed to predict the response of multi-bolt joints (damage area and failure load) by using the response in single-bolt CBJ as an initial baseline.
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finite element analysis of catastrophic failure of dynamically loaded countersunk composite fuselage joints
Composite Structures, 2015Co-Authors: Brian Egan, R M Frizzell, M A Mccarthy, C T MccarthyAbstract:Abstract Accurate models of dynamic structural failure are important for crashworthiness studies. To date, catastrophic failure of dynamically-loaded composite bolted joints has been studied using global or stacked shell element models. In this paper, high-fidelity (three-dimensional solid) explicit FE models are used to simulate catastrophic failure of countersunk composite fuselage joints. While current state-of-the-art 3D modelling approaches focus almost exclusively on the prediction of composite damage, this study also investigates the treatment of fastener damage. Fastener fracture is a common catastrophic joint failure mode, particularly in joints designed to initially fail in bearing. A Johnson–Cook material model and cohesive elements were used to predict plasticity, damage and fracture of the titanium (Ti–6Al–4V) fastener. Although a model calibration was required, due to the complex interaction of model parameters, numerical results demonstrate key trends of experiments and provide a starting point for the development of more predictive approaches for simulating fastener failure.
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modelling a single bolt countersunk composite joint using implicit and explicit finite element analysis
Computational Materials Science, 2012Co-Authors: Brian Egan, C T Mccarthy, M A Mccarthy, P.j. Gray, R M FrizzellAbstract:Abstract In this paper the mechanical behaviour of a composite joint incorporating a single countersunk fastener is investigated both experimentally and numerically. Results from an explicit dynamics model are compared to those obtained from an implicit modelling approach and measurements from experimental tests. The explicit dynamics method is of interest due to its robust contact modelling, and the scalability of the procedure for application to large structures. The deformation of the joint models in the overlap region is verified experimentally using extensometers. Experimental measures of secondary bending, obtained using 3D digital image correlation (DIC), provide good agreement with the numerical results.
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stress analysis of single bolt single lap countersunk composite joints with variable bolt hole clearance
Composite Structures, 2012Co-Authors: Brian Egan, C T Mccarthy, M A Mccarthy, R M FrizzellAbstract:Abstract Single-lap, carbon–epoxy joints with countersunk fasteners were modelled using the nonlinear finite element code Abaqus. A highly-detailed analysis of the stress distribution at the countersunk hole boundary is provided. Bolt-hole clearance, which arises due to limitations in manufacturing capabilities, is modelled extensively. Clearance levels both inside and outside typical aerospace fitting tolerances are studied and the finite element model is validated with experimental data. Plots of radial stress in each ply of the countersunk laminate show the load transfer to be severely localised, with only a few plies bearing the majority of the load. The inclusion of clearance in the model was shown to result in far higher radial stresses compared to those in the neat-fit joint model. An associated loss in joint stiffness of more than 10% was recorded for the highest clearance considered (240 μm). Finally compressive through-thickness stresses are shown to be present at the damageable region of the countersunk hole, and increase with bolt-hole clearance. These compressive stresses, which are an indicator of lateral constraint, are seen to suppress “brooming” failure in the countersunk laminate.
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bolt hole clearance effects and strength criteria in single bolt single lap composite bolted joints
Composites Science and Technology, 2002Co-Authors: M A Mccarthy, W F Stanley, V P Lawlor, C T MccarthyAbstract:Abstract Effects of bolt-hole clearance on the stiffness and strength of composite bolted joints were investigated. The configuration studied was single-lap, single-bolt. Four different clearances were obtained using variable size reamers, ranging from neat-fit to 240 μm. The specimens were manufactured in accordance with ASTM standard D5961/D5961 M-96, from graphite/epoxy HTA/6376, with quasi-isotropic and zero-dominated lay-ups. Both protruding head and countersunk bolts were used, with two different applied torque levels. Specimen dimensions were chosen to obtain bearing as the primary mode of failure, with ultimate failure being mostly through bolt failure. Joint stiffness, 2% offset bearing strength, ultimate bearing strength and ultimate bearing strain were obtained according to the Standard. In addition, an alternative definition of strength was derived, which has some advantages over the offset method, and the results were evaluated according to this definition. Increasing clearance was found to result in reduced joint stiffness and increased ultimate strain in all tested configurations. Finger-tight joints with protruding head bolts showed a link between clearance and strength, but countersunk and torqued joints did not. A delay in load take-up also occurred with the higher clearance joints, which has implications for load distributions in multi-bolt joints.
R M Frizzell - One of the best experts on this subject based on the ideXlab platform.
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finite element analysis of catastrophic failure of dynamically loaded countersunk composite fuselage joints
Composite Structures, 2015Co-Authors: Brian Egan, R M Frizzell, M A Mccarthy, C T MccarthyAbstract:Abstract Accurate models of dynamic structural failure are important for crashworthiness studies. To date, catastrophic failure of dynamically-loaded composite bolted joints has been studied using global or stacked shell element models. In this paper, high-fidelity (three-dimensional solid) explicit FE models are used to simulate catastrophic failure of countersunk composite fuselage joints. While current state-of-the-art 3D modelling approaches focus almost exclusively on the prediction of composite damage, this study also investigates the treatment of fastener damage. Fastener fracture is a common catastrophic joint failure mode, particularly in joints designed to initially fail in bearing. A Johnson–Cook material model and cohesive elements were used to predict plasticity, damage and fracture of the titanium (Ti–6Al–4V) fastener. Although a model calibration was required, due to the complex interaction of model parameters, numerical results demonstrate key trends of experiments and provide a starting point for the development of more predictive approaches for simulating fastener failure.
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Modelling bearing failure in countersunk composite joints under quasi-static loading using 3D explicit finite element analysis
Composite Structures, 2014Co-Authors: Brian Egan, R M Frizzell, Michael A. Mccarthy, P.j. Gray, Conor T. MccarthyAbstract:Abstract Three-dimensional explicit finite element modelling is used to predict the quasi-static bearing response of typical countersunk composite fuselage skin joints. In order to accurately simulate bearing failure, a user-defined 3D composite damage model was formulated for Abaqus/Explicit and included Puck failure criteria, a nonlinear shear law and a crack band model to mitigate mesh sensitivity. A novel approach was developed to employ characteristic element lengths which account for the orientation of composite ply cracks in the Abaqus/Explicit solver. Resulting models accurately predicted initial joint sticking behaviour and the elastic loading response of single-bolt and three-bolt joints, but preliminary predictions of bearing failure onset were overly-conservative. Improved failure predictions were obtained by utilising a fracture energy for compressive fibre failure which was considered more relevant for simulating bearing damage. The explicit models were exceptionally robust, showing capability to predict extensive hole crushing. Methods of dramatically improving joint model efficiency were highlighted.
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modelling a single bolt countersunk composite joint using implicit and explicit finite element analysis
Computational Materials Science, 2012Co-Authors: Brian Egan, C T Mccarthy, M A Mccarthy, P.j. Gray, R M FrizzellAbstract:Abstract In this paper the mechanical behaviour of a composite joint incorporating a single countersunk fastener is investigated both experimentally and numerically. Results from an explicit dynamics model are compared to those obtained from an implicit modelling approach and measurements from experimental tests. The explicit dynamics method is of interest due to its robust contact modelling, and the scalability of the procedure for application to large structures. The deformation of the joint models in the overlap region is verified experimentally using extensometers. Experimental measures of secondary bending, obtained using 3D digital image correlation (DIC), provide good agreement with the numerical results.
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stress analysis of single bolt single lap countersunk composite joints with variable bolt hole clearance
Composite Structures, 2012Co-Authors: Brian Egan, C T Mccarthy, M A Mccarthy, R M FrizzellAbstract:Abstract Single-lap, carbon–epoxy joints with countersunk fasteners were modelled using the nonlinear finite element code Abaqus. A highly-detailed analysis of the stress distribution at the countersunk hole boundary is provided. Bolt-hole clearance, which arises due to limitations in manufacturing capabilities, is modelled extensively. Clearance levels both inside and outside typical aerospace fitting tolerances are studied and the finite element model is validated with experimental data. Plots of radial stress in each ply of the countersunk laminate show the load transfer to be severely localised, with only a few plies bearing the majority of the load. The inclusion of clearance in the model was shown to result in far higher radial stresses compared to those in the neat-fit joint model. An associated loss in joint stiffness of more than 10% was recorded for the highest clearance considered (240 μm). Finally compressive through-thickness stresses are shown to be present at the damageable region of the countersunk hole, and increase with bolt-hole clearance. These compressive stresses, which are an indicator of lateral constraint, are seen to suppress “brooming” failure in the countersunk laminate.
M A Mccarthy - One of the best experts on this subject based on the ideXlab platform.
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finite element analysis of catastrophic failure of dynamically loaded countersunk composite fuselage joints
Composite Structures, 2015Co-Authors: Brian Egan, R M Frizzell, M A Mccarthy, C T MccarthyAbstract:Abstract Accurate models of dynamic structural failure are important for crashworthiness studies. To date, catastrophic failure of dynamically-loaded composite bolted joints has been studied using global or stacked shell element models. In this paper, high-fidelity (three-dimensional solid) explicit FE models are used to simulate catastrophic failure of countersunk composite fuselage joints. While current state-of-the-art 3D modelling approaches focus almost exclusively on the prediction of composite damage, this study also investigates the treatment of fastener damage. Fastener fracture is a common catastrophic joint failure mode, particularly in joints designed to initially fail in bearing. A Johnson–Cook material model and cohesive elements were used to predict plasticity, damage and fracture of the titanium (Ti–6Al–4V) fastener. Although a model calibration was required, due to the complex interaction of model parameters, numerical results demonstrate key trends of experiments and provide a starting point for the development of more predictive approaches for simulating fastener failure.
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modelling a single bolt countersunk composite joint using implicit and explicit finite element analysis
Computational Materials Science, 2012Co-Authors: Brian Egan, C T Mccarthy, M A Mccarthy, P.j. Gray, R M FrizzellAbstract:Abstract In this paper the mechanical behaviour of a composite joint incorporating a single countersunk fastener is investigated both experimentally and numerically. Results from an explicit dynamics model are compared to those obtained from an implicit modelling approach and measurements from experimental tests. The explicit dynamics method is of interest due to its robust contact modelling, and the scalability of the procedure for application to large structures. The deformation of the joint models in the overlap region is verified experimentally using extensometers. Experimental measures of secondary bending, obtained using 3D digital image correlation (DIC), provide good agreement with the numerical results.
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stress analysis of single bolt single lap countersunk composite joints with variable bolt hole clearance
Composite Structures, 2012Co-Authors: Brian Egan, C T Mccarthy, M A Mccarthy, R M FrizzellAbstract:Abstract Single-lap, carbon–epoxy joints with countersunk fasteners were modelled using the nonlinear finite element code Abaqus. A highly-detailed analysis of the stress distribution at the countersunk hole boundary is provided. Bolt-hole clearance, which arises due to limitations in manufacturing capabilities, is modelled extensively. Clearance levels both inside and outside typical aerospace fitting tolerances are studied and the finite element model is validated with experimental data. Plots of radial stress in each ply of the countersunk laminate show the load transfer to be severely localised, with only a few plies bearing the majority of the load. The inclusion of clearance in the model was shown to result in far higher radial stresses compared to those in the neat-fit joint model. An associated loss in joint stiffness of more than 10% was recorded for the highest clearance considered (240 μm). Finally compressive through-thickness stresses are shown to be present at the damageable region of the countersunk hole, and increase with bolt-hole clearance. These compressive stresses, which are an indicator of lateral constraint, are seen to suppress “brooming” failure in the countersunk laminate.
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bolt hole clearance effects and strength criteria in single bolt single lap composite bolted joints
Composites Science and Technology, 2002Co-Authors: M A Mccarthy, W F Stanley, V P Lawlor, C T MccarthyAbstract:Abstract Effects of bolt-hole clearance on the stiffness and strength of composite bolted joints were investigated. The configuration studied was single-lap, single-bolt. Four different clearances were obtained using variable size reamers, ranging from neat-fit to 240 μm. The specimens were manufactured in accordance with ASTM standard D5961/D5961 M-96, from graphite/epoxy HTA/6376, with quasi-isotropic and zero-dominated lay-ups. Both protruding head and countersunk bolts were used, with two different applied torque levels. Specimen dimensions were chosen to obtain bearing as the primary mode of failure, with ultimate failure being mostly through bolt failure. Joint stiffness, 2% offset bearing strength, ultimate bearing strength and ultimate bearing strain were obtained according to the Standard. In addition, an alternative definition of strength was derived, which has some advantages over the offset method, and the results were evaluated according to this definition. Increasing clearance was found to result in reduced joint stiffness and increased ultimate strain in all tested configurations. Finger-tight joints with protruding head bolts showed a link between clearance and strength, but countersunk and torqued joints did not. A delay in load take-up also occurred with the higher clearance joints, which has implications for load distributions in multi-bolt joints.
Liang Wang - One of the best experts on this subject based on the ideXlab platform.
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an experimental study on the effect of joining interface condition on bearing response of single lap countersunk composite aluminum bolted joints
Composite Structures, 2015Co-Authors: Yunong Zhai, Xiaoqiang Li, Dongsheng Li, Liang WangAbstract:Abstract An experimental study on the effect of joining interface condition (including shimming and interface gap) on bearing response of single-lap, countersunk composite-aluminum bolted joints are presented. The specimens consisted of a T700/3068 carbon/epoxy laminate with quasi-isotropic lay-up and an Aluminum alloy 7075T651 substrate. Bearing stress/bearing strain behavior were obtained according to ASTM standard. Both solid shim and liquid shim were considered and a comparison was made for them. 3D Digital Image Correlation was utilized to evaluate the effect of shimming on the surface strain distribution and out-of-plane deformation of the joints. One focus of the study was to investigate the effect of interface gap on the bearing performance of composite bolted joints. The interface gap was designed and characterized by variable parameters, i.e., thickness and span. It is found that compared to liquid-shim series, specimens with solid shim gain a little better bearing performance because of higher joint bending stiffness that benefits from the higher tensile modulus of solid peelable fiberglass shim. The presence of interface gap significantly weakens the bearing performance of single-lap, countersunk composite-aluminum joints by making the countersunk hole losing support from aluminum plate at the shear plane, and meanwhile intensifying the loading eccentricity of single-lap joints.
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an experimental study on the effect of bolt hole clearance and bolt torque on single lap countersunk composite joints
Composite Structures, 2015Co-Authors: Yunong Zhai, Xiaoqiang Li, Dongsheng Li, Liang WangAbstract:Abstract An experimental study on the effect of bolt-hole clearance and bolt torque on single-lap, single-bolt, countersunk composite joints are presented. The specimens were manufactured from carbon fiber/epoxy unitapes with quasi-isotropic lay-ups. Bearing stress/bearing strain behavior, bearing strength and joint stiffness were obtained according to ASTM standard D5961. The interaction between bolt-hole clearance and bolt torque on bearing response was evaluated by varying multiple parameters. One focus was to evaluate the surface strain distribution and the out-of-plane deformation of the joints by using a commercial 3D Digital Image Correlation (DIC) system. It is found that there is interaction between bolt-hole clearance and bolt torque on joint stiffness loss and 2% offset bearing strength. Furthermore, bolt-hole clearance intensifies the surface strain concentration and the out-of-plane deformation of the joints. Bolt torque alleviates the surface strain concentration, but has little effect on the out-of-plane deformation.
