The Experts below are selected from a list of 1680 Experts worldwide ranked by ideXlab platform
Jianjun Chen - One of the best experts on this subject based on the ideXlab platform.
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analysis of edge crack behavior of steel sheet in multi pass cold rolling based on a Shear modified gtn Damage model
Theoretical and Applied Fracture Mechanics, 2015Co-Authors: Jianjun ChenAbstract:Abstract Edge cracks are commonly observed in steel strip in cold rolling, which may cause deterioration of quality and productivity of products. The edge defect is one of the important factors that lead to edge cracks in cold rolling. In this paper, the GTN Damage model coupled with Shear Damage mechanism proposed by Nahshon and Hutchinson (2008) was employed to analyze the ductile Damage and failure behavior of steel sheet with edge defects under multi-pass cold rolling. Cold rolling experiments of silicon steel with edge notches were performed on an experimental rolling mill to verify the accuracy of the numerical results. The simulation results show that two cracks appeared in the notch tip after five passes rolling and extended toward the direction with an angle around 45° and 135° to the rolling direction, which was in good agreement with the experimental data. The influences of notch shape and size on the onset of cracks around the notch tip are investigated and some significant conclusions are drawn.
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prediction of edge crack in cold rolling of silicon steel strip based on an extended gurson tvergaard needleman Damage model
Journal of Manufacturing Science and Engineering-transactions of The Asme, 2015Co-Authors: Jianjun ChenAbstract:Edge cracking is commonly observed in cold rolling process. However, its failure mechanism is far from fully understanding due to the complex stresses and plastic flow conditions of steel strip under the rolling condition. In this paper, an extended Gurson–Tvergaard–Needleman (GTN) Damage model coupled with Nahshon–Hutchinson Shear Damage mechanism was introduced to investigate the Damage and fracture behavior of steel strip in cold rolling. The results show that extended GTN Damage model is efficient in predicting the occurrence of edge crack in cold rolling, and the prediction is more accurate than that of the original GTN Damage model. The edge cracking behavior under various cold rolling process parameters is investigated. It comes to the conclusion that edge crack extension increases with the increase of the reduction ratio, tension and the decrease of the roller radius and friction coefficient. The influence of Shear Damage becomes more significant in rolling condition with a larger reduction ratio, smaller roller radius, lower friction force, and tension.
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Prediction of Edge Crack in Cold Rolling of Silicon Steel Strip Based on an Extended Gurson–Tvergaard–Needleman Damage Model
Journal of Manufacturing Science and Engineering-transactions of The Asme, 2015Co-Authors: Jianjun ChenAbstract:Edge cracking is commonly observed in cold rolling process. However, its failure mechanism is far from fully understanding due to the complex stresses and plastic flow conditions of steel strip under the rolling condition. In this paper, an extended Gurson–Tvergaard–Needleman (GTN) Damage model coupled with Nahshon–Hutchinson Shear Damage mechanism was introduced to investigate the Damage and fracture behavior of steel strip in cold rolling. The results show that extended GTN Damage model is efficient in predicting the occurrence of edge crack in cold rolling, and the prediction is more accurate than that of the original GTN Damage model. The edge cracking behavior under various cold rolling process parameters is investigated. It comes to the conclusion that edge crack extension increases with the increase of the reduction ratio, tension and the decrease of the roller radius and friction coefficient. The influence of Shear Damage becomes more significant in rolling condition with a larger reduction ratio, smaller roller radius, lower friction force, and tension.
R Bochynek - One of the best experts on this subject based on the ideXlab platform.
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analysing and modelling the 3d Shear Damage behaviour of hybrid yarn textile reinforced thermoplastic composites
Composite Structures, 2011Co-Authors: W Hufenbach, Albert Langkamp, A Hornig, M Zscheyge, R BochynekAbstract:Abstract The presented work focuses on the examination of the 3D Shear Damage behaviour and its phenomenological failure process of a thermoplastic composite made of E-glass/polypropylene hybrid yarn with a woven reinforcement. Experimental Shear characterisation is performed by means of the Iosipescu testing approach for both in-plane and through-thickness directions. A procedure for the manufacturing of through-thickness Shear specimens is presented in this study. The characterisation of the chronological failure process and deformation analysis is supported by high speed camera system and Digital Image Correlation. Based on the experimental observations, material modelling strategies are derived and performed within the finite element environment Ls-Dyna.
Chaofang Dong - One of the best experts on this subject based on the ideXlab platform.
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Tearing failure of ultra-thin sheet-metal involving size effect in blanking process: Analysis based on modified GTN model
International Journal of Mechanical Sciences, 2017Co-Authors: Shen Wang, Zhanghua Chen, Chaofang DongAbstract:Abstract In this account, the ductile tearing behavior of a 0.08 mm thick ultra-thin martensitic stainless steel sheet was probed during the blanking process. The experiments suggested that void growth was suppressed around the narrow region due to the relatively low-stress triaxiality. The typical failure phenomena were exhibited in the form of tearing, which may imply that the conventional Gurson–Tvergaard–Needleman (GTN) model failed to predict such Shearing domination failure. Therefore, a modified GTN model based on Lode parameter was tested to describe the failure mechanism. Furthermore, to reflect the remarkable material strengthening behavior at the micrometer scale, the Mechanism-based Strain Gradient (MSG) plasticity was implemented in the User MATerial (UMAT) subroutine of ABAQUS, and a finite element model of three-dimensional blanking processing was then built. The cohesive elements were inserted into the finite element mesh so that the tearing process could be visualized. The numerical results generated by the proposed model were compared with the experimental observations, as well as data from conventional plasticity model. The analysis revealed that Shear Damage rather than microvoids was the primary cause of tearing failure. The effects of strain gradient on distributions of stress level, void volume fraction and Shear Damage evolution were examined. It was concluded that size effect played a significant role in inducing the tearing failure, and the modified GTN model was able to capture Shear Damage evolution inside the Shear region.
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Investigation and prediction of tearing failure during extrusion based on a modified Shear Damage model
Mechanics of Materials, 2017Co-Authors: Pengjing Zhao, Zhanghua Chen, Chaofang DongAbstract:Abstract In this study, a recent modified Shear GTN model suitable for various triaxialities was implemented and validated, which combines the porous plasticity model with a Damage mechanics concept. The original Gurson model was modified by coupling the Shear Damage and void volume fraction parameters into the yield surface. The stress update algorithm was developed via a user-material subroutine. With the help of representative volume elements (RVEs), a connection between the formation of macroscopic cracks and the microstructure was established. The modified GTN model was applied to predict the Damage and tearing fracture. Additionally, the cohesive zone model was applied to the RVE to simulate the de-bonding of the grain interfaces from a microscopic perspective. Metallurgical inspection by means of optical and scanning electron microscopy was performed to explore the failure mechanism and validate the numerical computation results. Furthermore, the deformation of the Shear band and the Damage propagation mechanism during the extrusion process were discussed.
Bradley R. Ringeisen - One of the best experts on this subject based on the ideXlab platform.
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Laser Printing of Single Cells: Statistical Analysis, Cell Viability, and Stress
Annals of Biomedical Engineering, 2005Co-Authors: Jason A. Barron, David B. Krizman, Bradley R. RingeisenAbstract:Methods to print patterns of mammalian cells to various substrates with high resolution offer unique possibilities to contribute to a wide range of fields including tissue engineering, cell separation, and functional genomics. This manuscript details experiments demonstrating that BioLP ^TM Biological Laser Printing, can be used to rapidly and accurately print patterns of single cells in a noncontact manner. Human osteosarcoma cells were deposited into a biopolymer matrix, and after 6 days of incubation, the printed cells are shown to be 100% viable. Printing low numbers of cells per spot by BioLP^TM is shown to follow a Poisson distribution, indicating that the reproducibility for the number of cells per spot is therefore determined not by the variance in printed volume per drop but by random sampling statistics. Potential cell Damage during the laser printing process is also investigated via immunocytochemical studies that demonstrate minimal expression of heat shock proteins by printed cells. Overall, we find that BioLP^TM is able to print patterns of osteosarcoma cells with high viability, little to no heat or Shear Damage to the cells, and at the ultimate single cell resolution.
Enrico Panettieri - One of the best experts on this subject based on the ideXlab platform.
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a non linear Shear Damage model to reproduce permanent indentation caused by impacts in composite laminates
Composite Structures, 2014Co-Authors: Daniele Fanteria, G Longo, Enrico PanettieriAbstract:Abstract For aeronautical composite structures impact Damage is an issue of great concern. In service Damage detection capability is related to the indentation left by impacts, thus it is crucial to understand the physical phenomena which control indentation. Recent studies suggest that indentation is greatly affected by the out-of-plane Shear properties of laminates, nevertheless the simulation of such behavior is still an open issue. A non-linear material model, including both in-plane and out-of-plane Shear, has been developed and implemented in an existing continuum-Damage-mechanics-based UMAT routine for the ABAQUS code. The enhanced code can simulate the indentation caused by impacts and it has been used to simulate tests according to ASTM D7136. The comparison of simulation results with those obtained by means of the original UMAT routine, implementing a simplified Shear model, allows the assessment of the importance of out-of-plane Shear in the simulation of impact events. A comparison between simulated time histories, of both contact force and absorbed energy, and the in-house experimentally measured ones shows a remarkable agreement, allowing the code to be validated. The non-linear out-of-plane Shear model also allows permanent indentations at the end of impact simulations be obtained, which are in good agreement with the experiments.
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A non-linear Shear Damage model to reproduce permanent indentation caused by impacts in composite laminates
Composite Structures, 2014Co-Authors: Daniele Fanteria, G Longo, Enrico PanettieriAbstract:For aeronautical composite structures impact Damage is an issue of great concern. In service Damage detection capability is related to the indentation left by impacts, thus it is crucial to understand the physical phenomena which control indentation.Recent studies suggest that indentation is greatly affected by the out-of-plane Shear properties of laminates, nevertheless the simulation of such behavior is still an open issue.A non-linear material model, including both in-plane and out-of-plane Shear, has been developed and implemented in an existing continuum-Damage-mechanics-based UMAT routine for the ABAQUS code. The enhanced code can simulate the indentation caused by impacts and it has been used to simulate tests according to ASTM D7136.The comparison of simulation results with those obtained by means of the original UMAT routine, implementing a simplified Shear model, allows the assessment of the importance of out-of-plane Shear in the simulation of impact events.A comparison between simulated time histories, of both contact force and absorbed energy, and the in-house experimentally measured ones shows a remarkable agreement, allowing the code to be validated.The non-linear out-of-plane Shear model also allows permanent indentations at the end of impact simulations be obtained, which are in good agreement with the experiments. © 2013 Elsevier Ltd.
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A non-linear model for in-plane Shear Damage and failure of composite laminates
Aerotecnica Missili & Spazio, 2014Co-Authors: Daniele Fanteria, Enrico PanettieriAbstract:Composite material characterization is typically carried out by time-consuming and expensive experimental tests aimed at establishing strengths at both lamina and laminate levels. In this scenario, numerical analyses are valuable tools in order to reduce the number of tests and to gather, at the same time, knowledge about the complex interactions of the composite Damage mechanisms. The paper presents a new constitutive model for the non-linear Shear behavior of composite laminates, which has been implemented in an user-defined Fortran routine (UMAT) to be used within ABAQUS non-linear FE code. A numerical model of the ASTM Standard V-notch specimen Shear test has been developed in order to identify the key parameters of the non-linear Shear constitutive model. This has been achieved by means of a systematic comparison of the numerical results with experimental data. Material anisotropy and the geometry of the notch have been found to cause the Shear strain field to be non-uniform in the notch section. This prevents a direct measure of the Shear constitutive law parameters, which must be alternatively evaluated through an indirect procedure. A modified notch geometry, which mitigates strain non-uniformities, has been evaluated and assessed through numerical simulations.
