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V Balasubramanian - One of the best experts on this subject based on the ideXlab platform.

  • effect of shoulder Diameter to Pin Diameter d d ratio on tensile strength and ductility of friction stir processed lm25aa 5 sicp metal matrix composites
    Materials & Design, 2014
    Co-Authors: P Vijayavel, V Balasubramanian, S Sundaram
    Abstract:

    Abstract Stir casted LM25AA-5% SiC Metal Matrix Composites (MMCs) consists of cast product dendrites and large agglomerated reinforced particle. The agglomeration of SiC creates difference in properties along the composite system. During loading it creates different stress field which causes failures in the composite material. Friction Stir Processing (FSP) is a novel processing technique facilitate by the frictional heat generation between the tool and the workpiece. FSP can triumph over the poor properties due to large sized and unevenly distributed SiC particle in the Al matrix. In this investigation, five different shoulder Diameters to Pin Diameter ( D / d ) ratio is used for processing the composite material. Tensile properties and hardness of the friction stir processed material were evaluated and correlated with the macro and microstructure signatures. The characterization of processed composite material is carried out using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and X-ray diffraction technique (XRD). The effect of different D / d ratio (2, 2.5, 3, 3.5, 4) on microstructural formation, particle size and distribution in the matrix were analysed and found that the D / d ratio of 3 yielded higher tensile and hardness properties.

  • predicting tensile strength hardness and corrosion rate of friction stir welded aa6061 t6 aluminium alloy joints
    Materials & Design, 2011
    Co-Authors: Sundaresan Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    Abstract AA6061-T 6 aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio and good corrosion resistance. The friction stir welding (FSW) process and tool parameters play major role in deciding the joint characteristics. In this research, the tensile strength and hardness along with the corrosion rate of friction-stir-butt welded joints of AA6061-T 6 aluminium alloy were investigated. The relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder Diameter, Pin Diameter and tool hardness) and the responses (tensile strength, hardness and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified and reported here.

  • influence of friction stir welding process and tool parameters on strength properties of aa7075 t6 aluminium alloy joints
    Materials & Design, 2011
    Co-Authors: Sundaresan Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    Abstract The aircraft aluminium alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an alternative improved way of satisfactorily producing aluminium joints, in a faster and reliable manner. In this present work, the influence of process and tool parameters on tensile strength properties of AA7075-T 6 joints produced by friction stir welding was analysed. Square butt joints were fabricated by varying process parameters and tool parameters. Strength properties of the joints were evaluated and correlated with the microstructure, microhardness of weld nugget. From this investigation it is found that the joint fabricated at a tool rotational speed of 1400 rpm, welding speed of 60 mm/min, axial force of 8 kN, using the tool with 15 mm shoulder Diameter, 5 mm Pin Diameter, 45 HRc tool hardness yielded higher strength properties compared to other joints.

  • optimization of the friction stir welding process and tool parameters to attain a maximum tensile strength of aa7075 t6 aluminium alloy
    Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 2010
    Co-Authors: S Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    AbstractHigh-strength, precipitation-hardening AA7075 alloy is used extensively in aircraft primary structures. The friction-stir-welding (FSW) process is an emerging solid-state joining process in which the material that is being welded does not melt and recast. The FSW process and tool parameters play a major role in deciding the joint strength. In this paper an attempt has been made to establish an empirical relationship between the FSW process and tool parameters (tool rotational speed, welding speed, axial force, shoulder Diameter, Pin Diameter, and tool material hardness) and the tensile strength of the joint. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the relationships. The developed empirical relationship can be effectively used to predict the tensile strength of FSW joints at the 95 per cent confidence level. A sensitivity analysis is also carried out and compared with the relative impact of input parameters on tensile streng...

Sundaresan Rajakumar - One of the best experts on this subject based on the ideXlab platform.

  • predicting tensile strength hardness and corrosion rate of friction stir welded aa6061 t6 aluminium alloy joints
    Materials & Design, 2011
    Co-Authors: Sundaresan Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    Abstract AA6061-T 6 aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio and good corrosion resistance. The friction stir welding (FSW) process and tool parameters play major role in deciding the joint characteristics. In this research, the tensile strength and hardness along with the corrosion rate of friction-stir-butt welded joints of AA6061-T 6 aluminium alloy were investigated. The relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder Diameter, Pin Diameter and tool hardness) and the responses (tensile strength, hardness and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified and reported here.

  • influence of friction stir welding process and tool parameters on strength properties of aa7075 t6 aluminium alloy joints
    Materials & Design, 2011
    Co-Authors: Sundaresan Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    Abstract The aircraft aluminium alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an alternative improved way of satisfactorily producing aluminium joints, in a faster and reliable manner. In this present work, the influence of process and tool parameters on tensile strength properties of AA7075-T 6 joints produced by friction stir welding was analysed. Square butt joints were fabricated by varying process parameters and tool parameters. Strength properties of the joints were evaluated and correlated with the microstructure, microhardness of weld nugget. From this investigation it is found that the joint fabricated at a tool rotational speed of 1400 rpm, welding speed of 60 mm/min, axial force of 8 kN, using the tool with 15 mm shoulder Diameter, 5 mm Pin Diameter, 45 HRc tool hardness yielded higher strength properties compared to other joints.

C. Muralidharan - One of the best experts on this subject based on the ideXlab platform.

  • predicting tensile strength hardness and corrosion rate of friction stir welded aa6061 t6 aluminium alloy joints
    Materials & Design, 2011
    Co-Authors: Sundaresan Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    Abstract AA6061-T 6 aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio and good corrosion resistance. The friction stir welding (FSW) process and tool parameters play major role in deciding the joint characteristics. In this research, the tensile strength and hardness along with the corrosion rate of friction-stir-butt welded joints of AA6061-T 6 aluminium alloy were investigated. The relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder Diameter, Pin Diameter and tool hardness) and the responses (tensile strength, hardness and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified and reported here.

  • influence of friction stir welding process and tool parameters on strength properties of aa7075 t6 aluminium alloy joints
    Materials & Design, 2011
    Co-Authors: Sundaresan Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    Abstract The aircraft aluminium alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an alternative improved way of satisfactorily producing aluminium joints, in a faster and reliable manner. In this present work, the influence of process and tool parameters on tensile strength properties of AA7075-T 6 joints produced by friction stir welding was analysed. Square butt joints were fabricated by varying process parameters and tool parameters. Strength properties of the joints were evaluated and correlated with the microstructure, microhardness of weld nugget. From this investigation it is found that the joint fabricated at a tool rotational speed of 1400 rpm, welding speed of 60 mm/min, axial force of 8 kN, using the tool with 15 mm shoulder Diameter, 5 mm Pin Diameter, 45 HRc tool hardness yielded higher strength properties compared to other joints.

  • optimization of the friction stir welding process and tool parameters to attain a maximum tensile strength of aa7075 t6 aluminium alloy
    Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 2010
    Co-Authors: S Rajakumar, C. Muralidharan, V Balasubramanian
    Abstract:

    AbstractHigh-strength, precipitation-hardening AA7075 alloy is used extensively in aircraft primary structures. The friction-stir-welding (FSW) process is an emerging solid-state joining process in which the material that is being welded does not melt and recast. The FSW process and tool parameters play a major role in deciding the joint strength. In this paper an attempt has been made to establish an empirical relationship between the FSW process and tool parameters (tool rotational speed, welding speed, axial force, shoulder Diameter, Pin Diameter, and tool material hardness) and the tensile strength of the joint. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the relationships. The developed empirical relationship can be effectively used to predict the tensile strength of FSW joints at the 95 per cent confidence level. A sensitivity analysis is also carried out and compared with the relative impact of input parameters on tensile streng...

Hassan Jazib - One of the best experts on this subject based on the ideXlab platform.

  • Effects of transient dynamic loading on the energy absorption capability of composite bolted joints undergoing extended bearing failure
    'Elsevier BV', 2022
    Co-Authors: Feser Thomas, Hassan Jazib, Waimer Matthias, Mccarthy C. T., Toso Nathalie, Voggenreiter Heinz, O'higgins, Ronan M., Mccarthy M. A.
    Abstract:

    peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 21/05/2022Carbon fibre reinforced polymer (CFRP) materials are widely used in transport aircraft. Crashworthiness requirements demand sufficient energy absorption capacity, especially in the fuselage structure. In a recently-proposed approach, specifically-designed “tension absorber” joints utilize tension loads for energy absorption via progressive bearing failure. For further development of the concept, experimental tests are performed on Pin- joints in quasi-isotropic CFRP material, under transient dynamic loading at 3 m/s. Investigated parameters are laminate thickness, stacking sequence and Pin Diameter, and the results are evaluated using the performance parameters ultimate bearing strength, mean crush stress and mass-specific energy absorption. A strong relation between the ratio of Pin Diameter to laminate thickness, D/t, and the performance parameters is found. Compared to previous results for quasi-static loading, the ultimate bearing strength is increased whereas the mean crush stress and mass-specific energy absorption are reduced. Digital image correlation and computed tomography analysis reveals the mechanisms behind the observed trends. The results provide a basis for further optimization of energy-absorbing joints and validation of finite element models

  • Experimental and numerical investigation of composite tension absorber joints for improved aircraft crashworthiness
    'Glucksman Library University of Limerick', 2021
    Co-Authors: Hassan Jazib
    Abstract:

    This thesis investigates the use of specially-designed “tension absorber” joints in composite vehicular structures for the absorption of energy in a crash situation through a process referred to here as “extended bearing failure”. The specific targeted application is future narrow-body composite aircraft fuselages which require an innovative energy absorption strategy due to the limited height available below the cargo floor for traditional crush beams. However, tension absorbers could be applied in any structure requiring energy-absorption capability in a crash or overload situation. Through a combined experimental-numerical approach, the work aims to provide fundamental information on the effects of geometric and material parameters such as stacking sequence, Pin Diameter, laminate thickness and loading rate, and an assessment of whether state-of-the-art numerical simulation is capable of providing genuinely predictive capability for such a complex problem. To make the results as useful as possible the chosen material is IM7/8552 carbon/epoxy, one of the most widely-characterised materials in the literature. Thus the results can be used by other researchers to test out modelling approaches without the need for further material testing. Besides the results in the published papers, videos provided as supplementary information contain complete three-dimensional (3D) maps of internal specimen damage, obtained from computed tomography (CT). The chosen performance parameters are ultimate bearing strength (UBS), mean crushing stress (MCS) and mass-specific energy absorption (SEA). Diameter-to-thickness (D/t) ratio is found to be an excellent predictor of UBS and SEA for both quasi-static and dynamic loading rates, with small D/t values giving best results, provided the thickness is sufficient to avoid global bending of the specimen. Concerning the effects of stacking sequence, it is found that the most important factor in maximising SEA is having small changes in orientation at ply interfaces. This is even more important than 0° content. Laminates with a high SEA tend to have a low UBS. Highest UBS was for quasi-isotropic laminates. Increased loading rate results in increased UBS but decreased SEA. The implemented model is a physically-based, three-dimensional damage model which uses in-situ ply strengths, stress-based fibre failure criteria, Puck’s criteria for matrix damage, a non-linear law for in-plane shear, a cohesive zone model for delamination, a crack-band model to mitigate mesh sensitivity, and frictional contact between the Pin and the laminate, and between plies once they delaminate. The developed model is found to accurately predict the global response in terms of strength and energy absorption and can forecast the effects of changing geometry and material parameters. Critically, comparison with CT scans shows that it also captures the key mesoscale damage mechanisms

  • Experimental and numerical investigation of composite tension absorber joints for improved aircraft crashworthiness
    'Glucksman Library University of Limerick', 2021
    Co-Authors: Hassan Jazib
    Abstract:

    peer-reviewedThis thesis investigates the use of specially-designed “tension absorber” joints in composite vehicular structures for the absorption of energy in a crash situation through a process referred to here as “extended bearing failure”. The specific targeted application is future narrow-body composite aircraft fuselages which require an innovative energy absorption strategy due to the limited height available below the cargo floor for traditional crush beams. However, tension absorbers could be applied in any structure requiring energy-absorption capability in a crash or overload situation. Through a combined experimental-numerical approach, the work aims to provide fundamental information on the effects of geometric and material parameters such as stacking sequence, Pin Diameter, laminate thickness and loading rate, and an assessment of whether state-of-the-art numerical simulation is capable of providing genuinely predictive capability for such a complex problem. To make the results as useful as possible the chosen material is IM7/8552 carbon/epoxy, one of the most widely-characterised materials in the literature. Thus the results can be used by other researchers to test out modelling approaches without the need for further material testing. Besides the results in the published papers, videos provided as supplementary information contain complete three-dimensional (3D) maps of internal specimen damage, obtained from computed tomography (CT). The chosen performance parameters are ultimate bearing strength (UBS), mean crushing stress (MCS) and mass-specific energy absorption (SEA). Diameter-to-thickness (D/t) ratio is found to be an excellent predictor of UBS and SEA for both quasi-static and dynamic loading rates, with small D/t values giving best results, provided the thickness is sufficient to avoid global bending of the specimen. Concerning the effects of stacking sequence, it is found that the most important factor in maximising SEA is having small changes in orientation at ply interfaces. This is even more important than 0° content. Laminates with a high SEA tend to have a low UBS. Highest UBS was for quasi-isotropic laminates. Increased loading rate results in increased UBS but decreased SEA. The implemented model is a physically-based, three-dimensional damage model which uses in-situ ply strengths, stress-based fibre failure criteria, Puck’s criteria for matrix damage, a non-linear law for in-plane shear, a cohesive zone model for delamination, a crack-band model to mitigate mesh sensitivity, and frictional contact between the Pin and the laminate, and between plies once they delaminate. The developed model is found to accurately predict the global response in terms of strength and energy absorption and can forecast the effects of changing geometry and material parameters. Critically, comparison with CT scans shows that it also captures the key mesoscale damage mechanisms

  • Effects of transient dynamic loading on the energy absorption capability of composite bolted joints undergoing extended bearing failure
    'Elsevier BV', 2020
    Co-Authors: Feser Thomas, Hassan Jazib, O'higgins Ronan, Waimer Matthias, Mccarthy C. T., Toso Nathalie, Voggenreiter Heinz, Mccarthy M. A.
    Abstract:

    Carbon fibre reinforced polymer (CFRP) materials are widely used in transport aircraft. Crashworthiness requirements demand sufficient energy absorption capacity, especially in the fuselage structure. In a recently-proposed approach, specifically-designed tension absorber joints utilize tension loads for energy absorption via progressive bearing failure. For further development of the concept, experimental tests are performed on Pin- joints in quasi-isotropic CFRP material, under transient dynamic loading at 3 m/s. Investigated parameters are laminate thickness, stacking sequence and Pin Diameter, and the results are evaluated using the performance parameters ultimate bearing strength, mean crush stress and mass-specific energy absorption. A strong relation between the ratio of Pin Diameter to laminate thickness, D/t, and the performance parameters is found. Compared to previous results for quasi-static loading, the ultimate bearing strength is increased whereas the mean crush stress and mass-specific energy absorption are reduced. Digital image correlation and computed tomography analysis reveals the mechanisms behind the observed trends. The results provide a basis for further optimization of energy-absorbing joints and validation of finite element models

  • Energy absorption capability of composite bolted joints undergoing extended bearing failure
    'Elsevier BV', 2020
    Co-Authors: Hassan Jazib, Feser Thomas, O'higgins Ronan, Waimer Matthias, Mccarthy C. T., Toso Nathalie, Byrne Michael, Mccarthy M. A.
    Abstract:

    Innovative crashworthiness strategies are needed for future narrow-body composite fuselage aircraft due to limited crash energy absorption capability below the cargo floor. A recently-proposed approach is to use specially-designed “tension absorber” joints which absorb energy through an extended bearing failure process. To explore the design space, experimental tests are performed on Pin-loaded joints in a widely-used carbon fibre/epoxy composite, with varying stacking sequence, Pin Diameter and laminate thickness. A bespoke rig is used to pull the Pin completely through the laminate. Performance parameters include ultimate bearing strength, mean crushing stress and mass-specific energy absorption. Three-dimensional computed tomography (3D CT) and scanning electron microscopy are used to examine failure and damage. Diameter-to-thickness ratio is found to be an excellent predictor of energy absorption, with small values giving best results, provided the thickness is sufficient to avoid global bending of the specimen. The use of a well-characterised material and availability of 3D CT data enables the results to be used for validation of analysis tools

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

  • Effects of transient dynamic loading on the energy absorption capability of composite bolted joints undergoing extended bearing failure
    'Elsevier BV', 2022
    Co-Authors: Feser Thomas, Hassan Jazib, Waimer Matthias, Mccarthy C. T., Toso Nathalie, Voggenreiter Heinz, O'higgins, Ronan M., Mccarthy M. A.
    Abstract:

    peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 21/05/2022Carbon fibre reinforced polymer (CFRP) materials are widely used in transport aircraft. Crashworthiness requirements demand sufficient energy absorption capacity, especially in the fuselage structure. In a recently-proposed approach, specifically-designed “tension absorber” joints utilize tension loads for energy absorption via progressive bearing failure. For further development of the concept, experimental tests are performed on Pin- joints in quasi-isotropic CFRP material, under transient dynamic loading at 3 m/s. Investigated parameters are laminate thickness, stacking sequence and Pin Diameter, and the results are evaluated using the performance parameters ultimate bearing strength, mean crush stress and mass-specific energy absorption. A strong relation between the ratio of Pin Diameter to laminate thickness, D/t, and the performance parameters is found. Compared to previous results for quasi-static loading, the ultimate bearing strength is increased whereas the mean crush stress and mass-specific energy absorption are reduced. Digital image correlation and computed tomography analysis reveals the mechanisms behind the observed trends. The results provide a basis for further optimization of energy-absorbing joints and validation of finite element models

  • Effects of transient dynamic loading on the energy absorption capability of composite bolted joints undergoing extended bearing failure
    'Elsevier BV', 2020
    Co-Authors: Feser Thomas, Hassan Jazib, O'higgins Ronan, Waimer Matthias, Mccarthy C. T., Toso Nathalie, Voggenreiter Heinz, Mccarthy M. A.
    Abstract:

    Carbon fibre reinforced polymer (CFRP) materials are widely used in transport aircraft. Crashworthiness requirements demand sufficient energy absorption capacity, especially in the fuselage structure. In a recently-proposed approach, specifically-designed tension absorber joints utilize tension loads for energy absorption via progressive bearing failure. For further development of the concept, experimental tests are performed on Pin- joints in quasi-isotropic CFRP material, under transient dynamic loading at 3 m/s. Investigated parameters are laminate thickness, stacking sequence and Pin Diameter, and the results are evaluated using the performance parameters ultimate bearing strength, mean crush stress and mass-specific energy absorption. A strong relation between the ratio of Pin Diameter to laminate thickness, D/t, and the performance parameters is found. Compared to previous results for quasi-static loading, the ultimate bearing strength is increased whereas the mean crush stress and mass-specific energy absorption are reduced. Digital image correlation and computed tomography analysis reveals the mechanisms behind the observed trends. The results provide a basis for further optimization of energy-absorbing joints and validation of finite element models

  • Energy absorption capability of composite bolted joints undergoing extended bearing failure
    'Elsevier BV', 2020
    Co-Authors: Hassan Jazib, Feser Thomas, O'higgins Ronan, Waimer Matthias, Mccarthy C. T., Toso Nathalie, Byrne Michael, Mccarthy M. A.
    Abstract:

    Innovative crashworthiness strategies are needed for future narrow-body composite fuselage aircraft due to limited crash energy absorption capability below the cargo floor. A recently-proposed approach is to use specially-designed “tension absorber” joints which absorb energy through an extended bearing failure process. To explore the design space, experimental tests are performed on Pin-loaded joints in a widely-used carbon fibre/epoxy composite, with varying stacking sequence, Pin Diameter and laminate thickness. A bespoke rig is used to pull the Pin completely through the laminate. Performance parameters include ultimate bearing strength, mean crushing stress and mass-specific energy absorption. Three-dimensional computed tomography (3D CT) and scanning electron microscopy are used to examine failure and damage. Diameter-to-thickness ratio is found to be an excellent predictor of energy absorption, with small values giving best results, provided the thickness is sufficient to avoid global bending of the specimen. The use of a well-characterised material and availability of 3D CT data enables the results to be used for validation of analysis tools

  • Effects of transient dynamic loading on the energy absorption capability of composite bolted joints undergoing extended bearing failure
    'Elsevier BV', 2020
    Co-Authors: Feser Thomas, Hassan Jazib, Waimer Matthias, Mccarthy C. T., Toso Nathalie, Voggenreiter Heinz, O\u27higgins, Ronan M., Mccarthy M. A.
    Abstract:

    The full text of this article will not be available in ULIR until the embargo expires on the 21/05/2022Carbon fibre reinforced polymer (CFRP) materials are widely used in transport aircraft. Crashworthiness requirements demand sufficient energy absorption capacity, especially in the fuselage structure. In a recently-proposed approach, specifically-designed “tension absorber” joints utilize tension loads for energy absorption via progressive bearing failure. For further development of the concept, experimental tests are performed on Pin- joints in quasi-isotropic CFRP material, under transient dynamic loading at 3 m/s. Investigated parameters are laminate thickness, stacking sequence and Pin Diameter, and the results are evaluated using the performance parameters ultimate bearing strength, mean crush stress and mass-specific energy absorption. A strong relation between the ratio of Pin Diameter to laminate thickness, D/t, and the performance parameters is found. Compared to previous results for quasi-static loading, the ultimate bearing strength is increased whereas the mean crush stress and mass-specific energy absorption are reduced. Digital image correlation and computed tomography analysis reveals the mechanisms behind the observed trends. The results provide a basis for further optimization of energy-absorbing joints and validation of finite element models