The Experts below are selected from a list of 591 Experts worldwide ranked by ideXlab platform
Shahzad Ahmad - One of the best experts on this subject based on the ideXlab platform.
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processing technologies for Nomex Honeycomb composites nhcs a critical review
Composite Structures, 2020Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Zhijun Wu, Pingfa Feng, Ma KeAbstract:Abstract Nomex Honeycomb composites have been paid significant attention for high performance structural applications in sandwich structures of aircrafts, aerospace, automotive, defense and so on. Both academia and industry have consensus that thin cell walls, cellular (hexagonal) structure, entrapped air inside cells, sandwich layers of phenolic resins (soft) and aramid fibers (brittle) enhance the machining complexity of Nomex Honeycomb composites and high quality processing on commercial scale remains a challenging task. Therefore, a wide spectrum of research was extremely required to fully exploit the potential of suitable processing technologies for Nomex Honeycomb composites. This paper systematically presents a comprehensive literature review on the processing complexity of Nomex Honeycomb composites and particularly emphasis on the design issues of processing technologies, influence of conventional and ultrasonic processing technologies on surface quality and cutting forces, impact of cutting tools design factors and processing parameters on the performance of the machining systems, mechanical properties and microstructural topographies of Nomex Honeycomb composites, research developments of material removal technologies and associated processing mechanisms, fixture methods, current challenges and future research scope. Moreover, the present study provides comprehensive guidelines and technological insights for high quality processing of Nomex Honeycomb composites.
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experimental study on rotary ultrasonic machining rum characteristics of Nomex Honeycomb composites nhcs by circular knife cutting tools
Journal of Manufacturing Processes, 2020Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Pingfa Feng, Zhijun WuAbstract:Abstract Heterogeneous material properties and complex cellular hexagonal thin-walled lightweight structure of Nomex Honeycomb composites (NHCs) pose significant challenges to achieve high quality processing in terms of low machinability, specialized cutting tools design, precision and influence of processing parameters on surface quality and cutting force. Surface defects have substantial impact on the functional performance and service life of sandwich structural components of NHCs used in aerospace, defense and automotive industries. In this paper, series of single factor and four-factors 4-levels orthogonal experiments were performed to study the effects of processing parameters on rotary ultrasonic machining (RUM) characteristics in terms of cutting force and surface quality by ultrasonic circular saw blade (UCSB) and ultrasonic circular knife (UCK) cutting tools. Furthermore, comparison of NHCs core workpiece cutting on RUM machine tool with ultrasonic vibration (UV) and without UV was conducted by both UCK and UCSB cutting tools. Experimental results proved that the cutting force increases with increase in feed rate and cutting depth whereas, it shows inverse relation with spindle speed and vibration amplitude. Cutting width has greater influence on cutting force among all processing parameters. UCK cutting tool generates less number of burr but length of burr is long and some tearing defects exists whereas, UCSB cutting tool produces large number of burr with very short burr length, no tearing defects and no uncut fibers. Moreover, NHCs core workpiece cutting on RUM machine tool with UV gives better surface quality and lower cutting force compared to without UV. The present study can be used as basis for comprehensive understanding of NHCs processing mechanism, cutting tools design and processing parameters optimization.
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Research on Design and FE Simulations of Novel Ultrasonic Circular Saw Blade (UCSB) Cutting Tools for Rotary Ultrasonic Machining of Nomex Honeycomb Composites
2019 16th International Bhurban Conference on Applied Sciences and Technology (IBCAST), 2019Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Zhijun Wu, Pingfa Feng, Ma KeAbstract:Due to low density, very thin cell walls and hexagonal cell structure, Nomex Honeycomb composites are considered as difficult to machine materials. CNC machining is the most common method used for the cutting of Nomex Honeycomb composites but required machining qualities of the Nomex Honeycomb composites components are not satisfactory due to various machining defects. Therefore, a new nontraditional machining technology rotary ultrasonic machining has been introduced to overcome the machining problems of Nomex Honeycomb composites because of intermittent contact of cutting tool with workpiece, low cutting force and better machining quality. In this research, a novel Ultrasonic Circular Saw Blade (UCSB) cutting tool and Ultrasonic Circular Knife (UCK) Cutting Tool are introduced and designed for ultrasonic machining of Nomex Honeycomb composites. Impact of different structural parameters of UCK and UCSB cutting tools on resonant frequency is investigated by FE simulations modal analysis technique on ANSYS workbench. Designs of cutting tools are verified by comparing FE simulations with experimental results and it showed that the resonant frequency and amplitude of cutting tools are good enough to perform rotary ultrasonic machining of Nomex Honeycomb composites.
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Design and Implementation of a Mini Ultrasonic Cutting System for Nomex Honeycomb Composites
2019 16th International Bhurban Conference on Applied Sciences and Technology (IBCAST), 2019Co-Authors: Ma Ke, Zhang Jianfu, Wu Zhijun, Yu Dingwen, Feng Pingfa, Shahzad AhmadAbstract:With great heat resistance, corrosion resistance, high specific strength and excellent mechanical properties, Nomex Honeycomb composites are widely used in aerospace industry. However, due to the special properties of the Nomex Honeycomb composites, traditional high-speed milling is difficult to complete the processing of the material. The ultrasonic processing method is one of the best ways to solve the above problem. In order to improve the ultrasonic power, the size of the ultrasound system structure is normally very large, which is inconvenient and uneconomical for processing the Nomex Honeycomb composites. A mini ultrasonic cutting system for paper - based Honeycomb material is designed in this paper. Its output amplitude is realized under the condition of small size, and its processing performance is verified by experiments. Based on the theoretical analysis, the design parameters of the presented mini ultrasonic cutting system were calculated. The resonant frequency, magnification and amplitude of the system were analyzing by simulation and amplitude test. The results showed the system parameters are consistent with the design value. The processing experiments of the Honeycomb material indicated the system can effectively reduce the cutting force and improve the surface quality.
Zhijun Wu - One of the best experts on this subject based on the ideXlab platform.
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processing technologies for Nomex Honeycomb composites nhcs a critical review
Composite Structures, 2020Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Zhijun Wu, Pingfa Feng, Ma KeAbstract:Abstract Nomex Honeycomb composites have been paid significant attention for high performance structural applications in sandwich structures of aircrafts, aerospace, automotive, defense and so on. Both academia and industry have consensus that thin cell walls, cellular (hexagonal) structure, entrapped air inside cells, sandwich layers of phenolic resins (soft) and aramid fibers (brittle) enhance the machining complexity of Nomex Honeycomb composites and high quality processing on commercial scale remains a challenging task. Therefore, a wide spectrum of research was extremely required to fully exploit the potential of suitable processing technologies for Nomex Honeycomb composites. This paper systematically presents a comprehensive literature review on the processing complexity of Nomex Honeycomb composites and particularly emphasis on the design issues of processing technologies, influence of conventional and ultrasonic processing technologies on surface quality and cutting forces, impact of cutting tools design factors and processing parameters on the performance of the machining systems, mechanical properties and microstructural topographies of Nomex Honeycomb composites, research developments of material removal technologies and associated processing mechanisms, fixture methods, current challenges and future research scope. Moreover, the present study provides comprehensive guidelines and technological insights for high quality processing of Nomex Honeycomb composites.
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experimental study on rotary ultrasonic machining rum characteristics of Nomex Honeycomb composites nhcs by circular knife cutting tools
Journal of Manufacturing Processes, 2020Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Pingfa Feng, Zhijun WuAbstract:Abstract Heterogeneous material properties and complex cellular hexagonal thin-walled lightweight structure of Nomex Honeycomb composites (NHCs) pose significant challenges to achieve high quality processing in terms of low machinability, specialized cutting tools design, precision and influence of processing parameters on surface quality and cutting force. Surface defects have substantial impact on the functional performance and service life of sandwich structural components of NHCs used in aerospace, defense and automotive industries. In this paper, series of single factor and four-factors 4-levels orthogonal experiments were performed to study the effects of processing parameters on rotary ultrasonic machining (RUM) characteristics in terms of cutting force and surface quality by ultrasonic circular saw blade (UCSB) and ultrasonic circular knife (UCK) cutting tools. Furthermore, comparison of NHCs core workpiece cutting on RUM machine tool with ultrasonic vibration (UV) and without UV was conducted by both UCK and UCSB cutting tools. Experimental results proved that the cutting force increases with increase in feed rate and cutting depth whereas, it shows inverse relation with spindle speed and vibration amplitude. Cutting width has greater influence on cutting force among all processing parameters. UCK cutting tool generates less number of burr but length of burr is long and some tearing defects exists whereas, UCSB cutting tool produces large number of burr with very short burr length, no tearing defects and no uncut fibers. Moreover, NHCs core workpiece cutting on RUM machine tool with UV gives better surface quality and lower cutting force compared to without UV. The present study can be used as basis for comprehensive understanding of NHCs processing mechanism, cutting tools design and processing parameters optimization.
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Research on Design and FE Simulations of Novel Ultrasonic Circular Saw Blade (UCSB) Cutting Tools for Rotary Ultrasonic Machining of Nomex Honeycomb Composites
2019 16th International Bhurban Conference on Applied Sciences and Technology (IBCAST), 2019Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Zhijun Wu, Pingfa Feng, Ma KeAbstract:Due to low density, very thin cell walls and hexagonal cell structure, Nomex Honeycomb composites are considered as difficult to machine materials. CNC machining is the most common method used for the cutting of Nomex Honeycomb composites but required machining qualities of the Nomex Honeycomb composites components are not satisfactory due to various machining defects. Therefore, a new nontraditional machining technology rotary ultrasonic machining has been introduced to overcome the machining problems of Nomex Honeycomb composites because of intermittent contact of cutting tool with workpiece, low cutting force and better machining quality. In this research, a novel Ultrasonic Circular Saw Blade (UCSB) cutting tool and Ultrasonic Circular Knife (UCK) Cutting Tool are introduced and designed for ultrasonic machining of Nomex Honeycomb composites. Impact of different structural parameters of UCK and UCSB cutting tools on resonant frequency is investigated by FE simulations modal analysis technique on ANSYS workbench. Designs of cutting tools are verified by comparing FE simulations with experimental results and it showed that the resonant frequency and amplitude of cutting tools are good enough to perform rotary ultrasonic machining of Nomex Honeycomb composites.
Christophe Bouvet - One of the best experts on this subject based on the ideXlab platform.
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damage mechanics modelling of the shear nonlinear behavior of Nomex Honeycomb core application to sandwich beams
Mechanics of Advanced Materials and Structures, 2020Co-Authors: Juan De Dios Rodriguezramirez, Bruno Castanié, Christophe BouvetAbstract:In this work, a modelling strategy based on damage mechanics is presented for Nomex Honeycomb core. The proposed approach is based on the experimental analysis presented by the authors in [1] and consists of the decoupled modelling of the buckling and collapse of cells for the HRH-78 Nomex Honeycomb core with two damage parameters. The proposed approach shows good agreementwith the experimental tests. The computational cost is low, proving the efficacy of this technique. This strategy may avoid using full 3D models that mimic the real shape and is a step toward a full compression/shear nonlinear model for Honeycomb core.
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Shear nonlinear behavior of the Nomex Honeycomb core
2018Co-Authors: Juan De Dios Rodriguez-ramirez, Bruno Castanié, Christophe BouvetAbstract:Sandwich structures are widely used for many different applications since they offer exceptional benefits, providing a high bending stiffness with a very low weight. In aeronautics, sandwich panels are commonly made of Nomex Honeycomb, and therefore this core has been studied for decades. Concerning the literature, most of the investigations on Honeycomb cores are focused on to investigate the compression properties of the structure, for energy absorption applications or impacts on sandwich panels. In the other hand, there are far fewer studies concerning the understanding of the shear nonlinear behavior of the Honeycomb [1], this can be considered a major drawback, knowing that it’s the core who absorbs most of the shear components when a bending force is applied. To help fill this gap, this work focuses on to study the shear behavior of the Honeycomb structure. Several experimental tests are conducted using different boundary conditions to observe the buckling of the cells. This helps to understand the causes of the phenomenological stages that appear when the Honeycomb structure is submitted to shear loads. Finally, a numerical approach is used to simulate the Honeycomb response to be able to see on the interior cell walls and to better understand this phenomenon. This work is a contribution to the understanding of the shear buckling of Nomex Honeycomb cores.
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Experimental and numerical analysis of the shear nonlinear behaviour of Nomex Honeycomb core: Application to insert sizing
Composite Structures, 2018Co-Authors: Juan De Dios Rodriguez-ramirez, Bruno Castanié, Christophe BouvetAbstract:This work is a contribution to the understanding of the nonlinear shear behaviour caused by cell postbuckling in Nomex Honeycomb cores. First, an experimental benchmark study was made of different designs for the shear testing of Honeycomb cores. Then, several test specimens were fabricated and tested, a 3D DIC system being used to measure and record the displacements. An Artificial Neural Network (ANN) was also used to identify the onset of bucking and collapse of the cells. The influence of the overall boundary conditions of shear tests on the buckling of the cells is presented both experimentally and numerically. The reversibility and test procedure results suggest that it may be possible to allow the shear strength to be increased by up to 35% under certain conditions.
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modelling of low energy low velocity impact on Nomex Honeycomb sandwich structures with metallic skins
International Journal of Impact Engineering, 2008Co-Authors: Bruno Castanié, Christophe Bouvet, Yulfian Aminanda, Jeanjacques Barrau, Pascal ThevenetAbstract:Abstract In the aircraft industry, manufacturers have to decide quickly whether an impacted sandwich needs repairing or not. Certain computation tools exist at present but they are very time-consuming and they also fail to perfectly model the physical phenomena involved in an impact. In a previous publication, the authors demonstrated the possibility of representing the Nomex™ Honeycomb core by a grid of nonlinear springs and have pointed out both the structural behaviour of the Honeycomb and the influence of core-skin boundary conditions. This discrete approach accurately predicts the static indentation on Honeycomb core alone and the indentation on sandwich structure with metal skins supported on rigid flat support. In this study, the domain of validity of this approach is investigated. It is found that the approach is not valid for sharp projectiles on thin skins. In any case, the spring elements used to model the Honeycomb cannot take into account the transverse shear that occurs in the core during the bending of a sandwich. To overcome this strong limitation, a multi-level approach is proposed in the present article. In this approach, the sandwich structure is modelled by Mindlin plate elements and the computed static contact law is implemented in a nonlinear spring located between the impactor and the structure. Thus, it is possible to predict the dynamic structural response in the case of low-velocity/low-energy impact on metal-skinned sandwich structures. A good correlation with dynamic experimental tests is achieved.
Ma Ke - One of the best experts on this subject based on the ideXlab platform.
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processing technologies for Nomex Honeycomb composites nhcs a critical review
Composite Structures, 2020Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Zhijun Wu, Pingfa Feng, Ma KeAbstract:Abstract Nomex Honeycomb composites have been paid significant attention for high performance structural applications in sandwich structures of aircrafts, aerospace, automotive, defense and so on. Both academia and industry have consensus that thin cell walls, cellular (hexagonal) structure, entrapped air inside cells, sandwich layers of phenolic resins (soft) and aramid fibers (brittle) enhance the machining complexity of Nomex Honeycomb composites and high quality processing on commercial scale remains a challenging task. Therefore, a wide spectrum of research was extremely required to fully exploit the potential of suitable processing technologies for Nomex Honeycomb composites. This paper systematically presents a comprehensive literature review on the processing complexity of Nomex Honeycomb composites and particularly emphasis on the design issues of processing technologies, influence of conventional and ultrasonic processing technologies on surface quality and cutting forces, impact of cutting tools design factors and processing parameters on the performance of the machining systems, mechanical properties and microstructural topographies of Nomex Honeycomb composites, research developments of material removal technologies and associated processing mechanisms, fixture methods, current challenges and future research scope. Moreover, the present study provides comprehensive guidelines and technological insights for high quality processing of Nomex Honeycomb composites.
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Research on Design and FE Simulations of Novel Ultrasonic Circular Saw Blade (UCSB) Cutting Tools for Rotary Ultrasonic Machining of Nomex Honeycomb Composites
2019 16th International Bhurban Conference on Applied Sciences and Technology (IBCAST), 2019Co-Authors: Shahzad Ahmad, Jianfu Zhang, Dingwen Yu, Zhijun Wu, Pingfa Feng, Ma KeAbstract:Due to low density, very thin cell walls and hexagonal cell structure, Nomex Honeycomb composites are considered as difficult to machine materials. CNC machining is the most common method used for the cutting of Nomex Honeycomb composites but required machining qualities of the Nomex Honeycomb composites components are not satisfactory due to various machining defects. Therefore, a new nontraditional machining technology rotary ultrasonic machining has been introduced to overcome the machining problems of Nomex Honeycomb composites because of intermittent contact of cutting tool with workpiece, low cutting force and better machining quality. In this research, a novel Ultrasonic Circular Saw Blade (UCSB) cutting tool and Ultrasonic Circular Knife (UCK) Cutting Tool are introduced and designed for ultrasonic machining of Nomex Honeycomb composites. Impact of different structural parameters of UCK and UCSB cutting tools on resonant frequency is investigated by FE simulations modal analysis technique on ANSYS workbench. Designs of cutting tools are verified by comparing FE simulations with experimental results and it showed that the resonant frequency and amplitude of cutting tools are good enough to perform rotary ultrasonic machining of Nomex Honeycomb composites.
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Design and Implementation of a Mini Ultrasonic Cutting System for Nomex Honeycomb Composites
2019 16th International Bhurban Conference on Applied Sciences and Technology (IBCAST), 2019Co-Authors: Ma Ke, Zhang Jianfu, Wu Zhijun, Yu Dingwen, Feng Pingfa, Shahzad AhmadAbstract:With great heat resistance, corrosion resistance, high specific strength and excellent mechanical properties, Nomex Honeycomb composites are widely used in aerospace industry. However, due to the special properties of the Nomex Honeycomb composites, traditional high-speed milling is difficult to complete the processing of the material. The ultrasonic processing method is one of the best ways to solve the above problem. In order to improve the ultrasonic power, the size of the ultrasound system structure is normally very large, which is inconvenient and uneconomical for processing the Nomex Honeycomb composites. A mini ultrasonic cutting system for paper - based Honeycomb material is designed in this paper. Its output amplitude is realized under the condition of small size, and its processing performance is verified by experiments. Based on the theoretical analysis, the design parameters of the presented mini ultrasonic cutting system were calculated. The resonant frequency, magnification and amplitude of the system were analyzing by simulation and amplitude test. The results showed the system parameters are consistent with the design value. The processing experiments of the Honeycomb material indicated the system can effectively reduce the cutting force and improve the surface quality.
Bruno Castanié - One of the best experts on this subject based on the ideXlab platform.
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damage mechanics modelling of the shear nonlinear behavior of Nomex Honeycomb core application to sandwich beams
Mechanics of Advanced Materials and Structures, 2020Co-Authors: Juan De Dios Rodriguezramirez, Bruno Castanié, Christophe BouvetAbstract:In this work, a modelling strategy based on damage mechanics is presented for Nomex Honeycomb core. The proposed approach is based on the experimental analysis presented by the authors in [1] and consists of the decoupled modelling of the buckling and collapse of cells for the HRH-78 Nomex Honeycomb core with two damage parameters. The proposed approach shows good agreementwith the experimental tests. The computational cost is low, proving the efficacy of this technique. This strategy may avoid using full 3D models that mimic the real shape and is a step toward a full compression/shear nonlinear model for Honeycomb core.
-
Shear nonlinear behavior of the Nomex Honeycomb core
2018Co-Authors: Juan De Dios Rodriguez-ramirez, Bruno Castanié, Christophe BouvetAbstract:Sandwich structures are widely used for many different applications since they offer exceptional benefits, providing a high bending stiffness with a very low weight. In aeronautics, sandwich panels are commonly made of Nomex Honeycomb, and therefore this core has been studied for decades. Concerning the literature, most of the investigations on Honeycomb cores are focused on to investigate the compression properties of the structure, for energy absorption applications or impacts on sandwich panels. In the other hand, there are far fewer studies concerning the understanding of the shear nonlinear behavior of the Honeycomb [1], this can be considered a major drawback, knowing that it’s the core who absorbs most of the shear components when a bending force is applied. To help fill this gap, this work focuses on to study the shear behavior of the Honeycomb structure. Several experimental tests are conducted using different boundary conditions to observe the buckling of the cells. This helps to understand the causes of the phenomenological stages that appear when the Honeycomb structure is submitted to shear loads. Finally, a numerical approach is used to simulate the Honeycomb response to be able to see on the interior cell walls and to better understand this phenomenon. This work is a contribution to the understanding of the shear buckling of Nomex Honeycomb cores.
-
Experimental and numerical analysis of the shear nonlinear behaviour of Nomex Honeycomb core: Application to insert sizing
Composite Structures, 2018Co-Authors: Juan De Dios Rodriguez-ramirez, Bruno Castanié, Christophe BouvetAbstract:This work is a contribution to the understanding of the nonlinear shear behaviour caused by cell postbuckling in Nomex Honeycomb cores. First, an experimental benchmark study was made of different designs for the shear testing of Honeycomb cores. Then, several test specimens were fabricated and tested, a 3D DIC system being used to measure and record the displacements. An Artificial Neural Network (ANN) was also used to identify the onset of bucking and collapse of the cells. The influence of the overall boundary conditions of shear tests on the buckling of the cells is presented both experimentally and numerically. The reversibility and test procedure results suggest that it may be possible to allow the shear strength to be increased by up to 35% under certain conditions.
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discrete modeling of the crushing of Nomex Honeycomb core and application to impact and post impact behavior of sandwich structures
2013Co-Authors: Bruno Castanié, Yulfian Aminanda, Jeanjacques Barrau, Pascal ThevenetAbstract:In this chapter, an original method for modeling the behavior of sandwich structures during and after impact is proposed and validated. It is based on the demonstration that Nomex Honeycomb behaves in a post-buckling mode very early and that compression forces are taken up by the corners or vertical edges of the Honeycomb cells in the same way as they are in the stiffeners in aircraft structures. Thus it is possible to represent the Honeycomb discretely by a grid of springs located at the six corners of hexagonal cells. This approach represents the phenomenon of indentation on Honeycomb alone or on sandwiches very well. This approach provides an understanding of how the sandwich and the core behave under compression after impact. An original criterion based on a local core crush is tested and validated to compute the residual strength. To consider the bending response of sandwich structures, a multi-level approach is also proposed.
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modelling of low energy low velocity impact on Nomex Honeycomb sandwich structures with metallic skins
International Journal of Impact Engineering, 2008Co-Authors: Bruno Castanié, Christophe Bouvet, Yulfian Aminanda, Jeanjacques Barrau, Pascal ThevenetAbstract:Abstract In the aircraft industry, manufacturers have to decide quickly whether an impacted sandwich needs repairing or not. Certain computation tools exist at present but they are very time-consuming and they also fail to perfectly model the physical phenomena involved in an impact. In a previous publication, the authors demonstrated the possibility of representing the Nomex™ Honeycomb core by a grid of nonlinear springs and have pointed out both the structural behaviour of the Honeycomb and the influence of core-skin boundary conditions. This discrete approach accurately predicts the static indentation on Honeycomb core alone and the indentation on sandwich structure with metal skins supported on rigid flat support. In this study, the domain of validity of this approach is investigated. It is found that the approach is not valid for sharp projectiles on thin skins. In any case, the spring elements used to model the Honeycomb cannot take into account the transverse shear that occurs in the core during the bending of a sandwich. To overcome this strong limitation, a multi-level approach is proposed in the present article. In this approach, the sandwich structure is modelled by Mindlin plate elements and the computed static contact law is implemented in a nonlinear spring located between the impactor and the structure. Thus, it is possible to predict the dynamic structural response in the case of low-velocity/low-energy impact on metal-skinned sandwich structures. A good correlation with dynamic experimental tests is achieved.