The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform
A. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Impact Damage in Twin-walled Composite Structures
2006Co-Authors: A. Johnson, Nathalie Toso-pentecote, Rodolfo Aoki-sugiyamaAbstract:The presentation describes recent progress on damage assessment in novel aircraft sandwich structures subjected to foreign object impacts from both hard and soft impactors. A gas gun impact test programme was carried out on twin-walled composite panels under a range of impact conditions. Impact damage to the outer skins, core and inner skins was characterised by a number of NDE techniques, including ultrasonic C-scan, X-ray and lock-in thermography. The high velocity impact test programme was then used to validate simulation methods developed for the prediction of structural damage in composite structures under impact loads. Composites ply damage models and Interply Delamination models have been developed and implemented in commercial explicit FE codes. The failure models and code developments were applied to predict transverse impact damage in the sandwich skin laminates and penetration into the core. The paper assesses the effectiveness of NDE methods in capturing impact damage in these twin-walled structures and summarises the status of FE modelling techniques for damage modelling in composite aircraft structures.
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Modelling Soft Body Impact on Composite Structures
Composite Structures, 2003Co-Authors: A. Johnson, Martin HolzapfelAbstract:The paper describes recent progress on materials modelling and numerical simulation of soft body impact damage in fibre reinforced composite structures. The work is based on the application of finite element (FE) analysis codes to simulate composite shell structures under impact loads arising, for example, from bird strike on a wing leading edge. A composites ply damage mechanics model and Interply Delamination model have been implemented in an explicit FE code which is used to predict impact damage in shell structures. Soft body impactors such as gelatine (substitute bird) or ice (hailstones) are highly deformable on impact and flow over the structure spreading the impact load. They are modelled by a particle method in which the FE mesh is replaced by interacting particles. The failure models and code developments are applied to the numerical simulation of gas gun impact tests in which gelatine projectiles are fired at glass fabric/epoxy cylindrical shells.
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Design and modelling of composite structures under high velocity impact
2002Co-Authors: A. Johnson, Michael HolzapfelAbstract:The paper describes recent progress on materials modelling and numerical simulation of impact damage in fibre reinforced composite structures. This contributes to an important Workshop theme, namely the development of fast, reliable design tools for evaluating and later certifying composite fuselage structures under complex load conditions. The work is based on the application of finite element (FE) analysis codes to simulte composite shell structures under impact loads. An improved composites ply damage mechanics model and Interply Delamination model have been implemented in an explicit FE code which was used to predict impact damage in shell structures. The failure models and code developments are validated by comparing numerical simulations with gas gun impact test data on idealised composite aircraft structures such as cylindrical shells and sandwich panels.
Martin Holzapfel - One of the best experts on this subject based on the ideXlab platform.
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Modelling Soft Body Impact on Composite Structures
Composite Structures, 2003Co-Authors: A. Johnson, Martin HolzapfelAbstract:The paper describes recent progress on materials modelling and numerical simulation of soft body impact damage in fibre reinforced composite structures. The work is based on the application of finite element (FE) analysis codes to simulate composite shell structures under impact loads arising, for example, from bird strike on a wing leading edge. A composites ply damage mechanics model and Interply Delamination model have been implemented in an explicit FE code which is used to predict impact damage in shell structures. Soft body impactors such as gelatine (substitute bird) or ice (hailstones) are highly deformable on impact and flow over the structure spreading the impact load. They are modelled by a particle method in which the FE mesh is replaced by interacting particles. The failure models and code developments are applied to the numerical simulation of gas gun impact tests in which gelatine projectiles are fired at glass fabric/epoxy cylindrical shells.
Michael Holzapfel - One of the best experts on this subject based on the ideXlab platform.
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Numerical prediction of damage in composite structures from soft body impacts
Journal of Materials Science, 2006Co-Authors: Alastair F. Johnson, Michael HolzapfelAbstract:The paper summarises recent progress on materials modelling and numerical simulation of soft body impact damage in fibre reinforced composite aircraft structures. The work is based on the application of finite element (FE) analysis codes to simulate damage in composite shell structures under impact loads. Composites ply damage models and Interply Delamination models have been developed and implemented in commercial explicit FE codes. Models are discussed for predicting impact loads on aircraft structures arising from deformable soft bodies such as gelatine (synthetic bird) and ice (hailstone). The composites failure models and code developments are briefly summarised and applied in the paper to numerical simulation of synthetic bird impact on idealised composite aircraft structures.
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Design and modelling of composite structures under high velocity impact
2002Co-Authors: A. Johnson, Michael HolzapfelAbstract:The paper describes recent progress on materials modelling and numerical simulation of impact damage in fibre reinforced composite structures. This contributes to an important Workshop theme, namely the development of fast, reliable design tools for evaluating and later certifying composite fuselage structures under complex load conditions. The work is based on the application of finite element (FE) analysis codes to simulte composite shell structures under impact loads. An improved composites ply damage mechanics model and Interply Delamination model have been implemented in an explicit FE code which was used to predict impact damage in shell structures. The failure models and code developments are validated by comparing numerical simulations with gas gun impact test data on idealised composite aircraft structures such as cylindrical shells and sandwich panels.
Neidigk Stephen - One of the best experts on this subject based on the ideXlab platform.
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Detection and characterization of impact damage in carbon fiber aircraft fuselage structure
UNM Digital Repository, 2013Co-Authors: Neidigk StephenAbstract:As the use of advanced composite materials continues to grow in the aviation industry, damage detection techniques need to be developed and tested. Impact damage on aluminum aircraft structures can be detected from obvious surface indications. This is not the case in composite aircraft structure. Large Interply Delaminations and substructure disbonding may occur as a result of an impact, often leaving no visual indications of damage. This research investigates the use of conventional hand-deployed ultrasonic (UT) inspection techniques and more advanced UT pulse-echo and resonance scanning techniques to detect and characterize damage in full-scale carbon fiber fuselage structure. It also examines embedded and bonded methods of deploying an in-situ fiber optic (FO) Swept Wavelength Interferometry (SWI) strain sensing system for damage detection. The hypothesis is that the more advanced scanning nondestructive inspection (NDI) techniques used in the study will more effectively detect and characterize damage modes in the fuselage panels than hand-deployed UT techniques. It is further hypothesized that impact damage created by both simulated hail and steel spherical tip impacts will create a permanent, detectable strain change that can be detected by the FO strain measurement system. Two fuselage panels representative of structures seen on advanced composite transport category aircraft were fabricated. They each measured approximately 56 x 76\u27. The structural components consisted of a 16 ply skin, co-cured, hat-section stringers, fastened shear ties and frames. The material used to fabricate the panels was T800 unidirectional, carbon pre-preg and was processed in an autoclave. Simulated hail impact testing was conducted on the panels using a high velocity gas gun with 2.4\u27 diameter ice balls. The ice impact tests were performed in collaboration with the University of California San Diego (UCSD). In addition to the simulated hail impact testing, 2\u27 diameter spherical tip steel impacts were conducted to simulate impact damage introduced during heavy ground maintenance operations. The extent of 16 ply skin damage induced on the panels ranged from less than 1 in2 to 55 in2 of Interply Delamination. Substructure damage on the panels included shear tie cracking, Delamination of the built-up pad sections behind the fastened shear ties, and stringer-to-flange disbonding. Substructure damage away from the site of high energy ice impacts was often not detected with hand-deployed UT, which can be attributed to failure to inspect far enough away from the impact site. This additional damage was detected using the more advanced scanning techniques. Data collection from the embedded FO was not possible due to light attenuation caused by micro-bending induced in the fiber. It was determined that increasing both the numerical aperture of the FO and the diameter, in combination with adjusting the layout orientation used, may make it possible to measure strain change using this technique. Detectable strain indications were obtained using the backside bonded FO in 15 of the 25 interrogated steel tip impacts. Increasing the robustness of this deployment method could provide a means for in-situ damage detection.\u2
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Detection and characterization of impact damage in carbon fiber aircraft fuselage structure
2013Co-Authors: Neidigk StephenAbstract:As the use of advanced composite materials continues to grow in the aviation industry, damage detection techniques need to be developed and tested. Impact damage on aluminum aircraft structures can be detected from obvious surface indications. This is not the case in composite aircraft structure. Large Interply Delaminations and substructure disbonding may occur as a result of an impact, often leaving no visual indications of damage. This research investigates the use of conventional hand-deployed ultrasonic (UT) inspection techniques and more advanced UT pulse-echo and resonance scanning techniques to detect and characterize damage in full-scale carbon fiber fuselage structure. It also examines embedded and bonded methods of deploying an in-situ fiber optic (FO) Swept Wavelength Interferometry (SWI) strain sensing system for damage detection. The hypothesis is that the more advanced scanning nondestructive inspection (NDI) techniques used in the study will more effectively detect and characterize damage modes in the fuselage panels than hand-deployed UT techniques. It is further hypothesized that impact damage created by both simulated hail and steel spherical tip impacts will create a permanent, detectable strain change that can be detected by the FO strain measurement system. Two fuselage panels representative of structures seen on advanced composite transport category aircraft were fabricated. They each measured approximately 56” x 76”. The structural components consisted of a 16 ply skin, co-cured, hat-section stringers, fastened shear ties and frames. The material used to fabricate the panels was T800 unidirectional, carbon pre-preg and was processed in an autoclave. Simulated hail impact testing was conducted on the panels using a high velocity gas gun with 2.4” diameter ice balls. The ice impact tests were performed in collaboration with the University of California San Diego (UCSD). In addition to the simulated hail impact testing, 2” diameter spherical tip steel impacts were conducted to simulate impact damage introduced during heavy ground maintenance operations. The extent of 16 ply skin damage induced on the panels ranged from less than 1 in2 to 55 in2 of Interply Delamination. Substructure damage on the panels included shear tie cracking, Delamination of the built-up pad sections behind the fastened shear ties, and stringer-to-flange disbonding. Substructure damage away from the site of high energy ice impacts was often not detected with hand-deployed UT, which can be attributed to failure to inspect far enough away from the impact site. This additional damage was detected using the more advanced scanning techniques. Data collection from the embedded FO was not possible due to light attenuation caused by micro-bending induced in the fiber. It was determined that increasing both the numerical aperture of the FO and the diameter, in combination with adjusting the layout orientation used, may make it possible to measure strain change using this technique. Detectable strain indications were obtained using the backside bonded FO in 15 of the 25 interrogated steel tip impacts. Increasing the robustness of this deployment method could provide a means for in-situ damage detection.Federal Aviation Administration - William J. Hughes Technical CenterCivil EngineeringMastersUniversity of New Mexico. Dept. of Civil EngineeringTaha, Mahmoud RedaMaji, ArupRoss, Timoth
Alastair F. Johnson - One of the best experts on this subject based on the ideXlab platform.
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COMPOSITE STRUCTURES
2014Co-Authors: E. Oñate, Alastair F. Johnson, D. R. J. Owen, Nathalie PentecôteAbstract:Summary. The paper describes recent progress on materials modelling and numerical simulation of foreign object impact damage in fibre reinforced composite aircraft structures. The work is based on the application of finite element (FE) analysis codes to simulate damage in composite shell structures under impact loads. Composites ply damage models and Interply Delamination models have been developed and implemented in commercial explicit FE codes. The failure models and code developments are validated in the paper by predicting transverse impact damage in composite aircraft sandwich structures and comparing numerical simulations with high velocity gas gun impact test data.
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Numerical prediction of damage in composite structures from soft body impacts
Journal of Materials Science, 2006Co-Authors: Alastair F. Johnson, Michael HolzapfelAbstract:The paper summarises recent progress on materials modelling and numerical simulation of soft body impact damage in fibre reinforced composite aircraft structures. The work is based on the application of finite element (FE) analysis codes to simulate damage in composite shell structures under impact loads. Composites ply damage models and Interply Delamination models have been developed and implemented in commercial explicit FE codes. Models are discussed for predicting impact loads on aircraft structures arising from deformable soft bodies such as gelatine (synthetic bird) and ice (hailstone). The composites failure models and code developments are briefly summarised and applied in the paper to numerical simulation of synthetic bird impact on idealised composite aircraft structures.
