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Liang Ying - One of the best experts on this subject based on the ideXlab platform.
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on the Thermal Forming limit diagram tfld with gtn mesoscopic damage model for aa7075 aluminum alloy numerical and experimental investigation
Journal of Alloys and Compounds, 2019Co-Authors: Liang Ying, Hai Rong, Ping HuAbstract:Abstract The formability of high strength AA7075 aluminum alloy under elevated temperatures is vital in guiding the fabrication of automobile structural parts. The ductile fracture Forming limit of AA7075 at elevated temperatures is essentially governed by Thermal damage evolution. In this paper, the hot tensile test (300oC-450 °C, strain rate 0.1s−1-0.001s−1) for AA7075 was conducted and the corresponding flow behavior was fitted by Hensiel-Spittel (HS) constitutive equation. The GTN mesoscopic damage model was implemented to take account of the damage evolution phenomenon of AA7075 at elevated temperatures. The temperature-dependent damage void volume fractions (VVF) were identified accurately based on a novel inverse identification procedure, named the CCD parameters design-FEM inverse simulation-genetic algorithm (CCD-FEIS-GA) optimization method. Subsequently, the Thermal Forming limit diagram (TFLD) was calculated based on the GTN damage parameters and further validated by hot Nakajima-type bulging experiment. The corresponding damage evolution behaviors and effects of critical Forming parameters were discussed in detail. The comparison of experimental and numerical results showed that the formability of AA7075 firstly increases and then decreases with the increasing Forming temperature, the TFLD0 reaches its maximum value when the temperature is 400 °C, and the formability also increases with the increasing strain rate and the decreasing surface coefficient of friction. The proposed simulated strategy coupled with mesoscopic GTN approach conduces to the accurate prediction of TFLD and damage fracture behavior of AA7075 in the hot Forming process.
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Thermal Forming limit diagram tfld of aa7075 aluminum alloy based on a modified continuum damage model experimental and theoretical investigations
International Journal of Mechanical Sciences, 2019Co-Authors: Hai Rong, Liang Ying, Ping Hu, Jinghuang ZhangAbstract:Abstract The formability of high strength Al-Zn-Mg-Cu (7000 series) aluminum alloys can be significantly improved at elevated temperatures, which has been paid more attention in recent decades. The formability of high strength aluminum alloys at elevated temperatures is essentially governed by Thermal-damage evolution. In this paper, the main purpose is to propose a modified continuum damage model to describe the damage evolution and predict the fracture behavior of AA7075 at elevated temperatures (300–400 °C). Firstly, the Thermal-mechanical behavior and Forming limit of AA7075 alloy sheet were experimentally investigated using a series of isoThermal uniaxial tensile tests and Nakajima tests at different temperatures and strain rates. A set of uniaxial continuum damage constitutive equations (CDCEs) coupling continuum damage mechanics (CDM) with unified viscoplastic theory was proposed to describe the uniaxial tensile behavior of AA7075. Subsequently, the uniaxial equations were extended into a set of multi-axial CDCEs by introducing a multi-axial damage correction formula to predict the TFLD of AA7075. Besides, the forward Euler method was employed to integrate the proposed CDCEs, and the corresponding material constants of CDCEs were further calibrated by the non-dominated sorting genetic algorithmⅡ(NSGA-Ⅱ). The results illustrate that the Thermal flow behavior and the TFLD of AA7075 alloy can be predicted successfully by the proposed damage model. Detailed discussions about the effects of corresponding parameters on the computed TFLD indicate the established multi-axial CDCEs are flexible and beneficial to the application potential in numerical simulation of hot sheet metal Forming.
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A Thermal Forming limit prediction method considering material damage for 22MnB5 sheet
The International Journal of Advanced Manufacturing Technology, 2017Co-Authors: Liu Wenquan, Liang Ying, Jinghuang Zhang, Dantong WangAbstract:Hot stamping of high-strength steel is an innovative technology to achieve automobile lightweight and guarantee security simultaneously. However, the formability of high-strength steel is still limited at elevated temperatures by the evolution of void damage inside materials. Thus, the establishment of an efficient Forming limit prediction method is urgently demanded. In the present work, the Gurson-Tvergaard-Needleman (GTN) model is extended by containing Hosford anisotropic yield criterion which can characterize void damage in normal anisotropic materials. The flow behavior of matrix material 22MnB5 at different Forming temperatures is simulated by the modified Norton-Hoff hardening law. And the damage-related parameters are calibrated through FEM inverse analysis. Furthermore, the prediction method of Forming limit combined with void damage is realized within the framework of the Marciniak and Kuczynski (M-K) model. Meanwhile, the high-temperature Nakazima test is conducted to obtain experimental Thermal Forming limit diagram (TFLD). The comparison of results by theoretical prediction and experimental test shows good consistency. Based on the proposed method, the effects of temperature, void damage, initial thickness imperfection, and anisotropy on the Forming limit are analyzed. The formability improved with the increasing of deformation temperature but worse for other factors.
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Experimental and numerical determination of Thermal Forming limit diagrams (TFLD) of high strength steel 22MnB5
2013Co-Authors: D. Y. Shi, Liang Ying, X. Zhao, W. Q. LiuAbstract:High strength steel components are increasingly being considered for use in vehicle structures due to the potential for higher strength to weight ratio, fuel economy improvement and emission reduction. However, high strength steel's poor ductility at room temperature requires sheet Forming to be carried out in hot Forming method. The Thermal Forming Limit Diagram (TFLD) is an important primary criterion to determine how close the sheet metal is to tearing when it is formed into a product shape in hot Forming process. In this work, an efficient experimental set-up named TFLD 300 which is based on Nakajima test has been developed. Several experiments for hot Forming limits of high strength steel 22MnB5 were performed and the Forming limit curves at different temperatures are obtained. Then the three-dimensional TFLD which considers temperature history and strain path is constructed. As an evaluation criterion for formability, the three-dimensional TFLD is introduced into KMAS (King Mesh Analysis System), which is independently developed commercial CAE software and can be used for hot Forming simulation. Subsequently, a typical B-pillar's hot Forming process with varying process conditions have been simulated by using the KMAS software. And the corresponding experiment results confirm that the KMAS software and three-dimensional TFLD can accurately predict the fracture of sheet metal in hot Forming.
Akio Ohtani - One of the best experts on this subject based on the ideXlab platform.
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Lightweight and anti-corrosive fiber reinforced thermoplastic rivet
Composite Structures, 2018Co-Authors: Masahito Ueda, Naoya Ui, Akio OhtaniAbstract:Abstract A lightweight anti-corrosive rivet is proposed using a fiber reinforced thermoplastic (FRTP) for the joining of carbon fiber reinforced plastic (CFRP). The FRTP rivet was fabricated via the braiding technique, where Glass fiber/PA66 commingled yarns were wrapped around straightly aligned Carbon fiber/PA66 commingled yarns. Using a pultrusion method, the braided yarn was consolidated into a FRTP rod, which was then cut to an appropriate length for use as a FRTP rivet. Quasi-isotropic CFRP laminates were joined by this rivet through a Thermal Forming process. Single-lap joint specimens were subjected to tensile tests, and compared with a bolted and blind-riveted joint. The joint strength increased with increasing fiber volume fraction of the FRTP rivet, which had a higher specific joint strength than the other metallic joints. The results revealed that, for the same joint strength, FRTP-rivet replacement of the metallic joint yields a reduction in the weight of the joint.
Xuefeng Wang - One of the best experts on this subject based on the ideXlab platform.
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Optimisation research on inductor shape parameters for Thermal Forming behaviour of ship hull plate by moving induction heating
Ships and Offshore Structures, 2019Co-Authors: Shuiming Zhang, Cungen Liu, Xuefeng WangAbstract:ABSTRACTThis paper mainly implemented optimisation research on inductor shape parameters for Thermal Forming behaviour of ship hull plate fabricated by moving induction heating, which can be evalua...
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Nondimensional prediction of Thermal Forming behaviour for the ship hull plate fabricated by induction heating
Ships and Offshore Structures, 2018Co-Authors: Shuiming Zhang, Cungen Liu, Xuefeng Wang, Zhi YangAbstract:ABSTRACTThis paper mainly investigated the nondimensional relation between technological parameters and Thermal Forming behaviour for the ship hull plate by induction heating, which can be evaluated by maximum temperature Tum, breadth b and depth h of the heat-affected zone (HAZ). The mutually coupled electromagnetic-Thermal analysis procedure considering temperature-dependent material properties at each step for the opposite-direction current-carrying inductor with the gap (ODIG) was implemented and validated by an experiment. L25(56) designs of the orthogonal test relative to five technological parameters were then conducted to yield Tum, b and h. Afterwards, critical technological parameters were obtained for Tum based on the ANOVA method, and subsequently utilised for major nondimensional factors through dimensional and correlation analyses. Finally, predictive relations of Tum, b and h were derived by multivariate regression. Furthermore, 18 sets of predicted Tum, b and h were employed for bending an...
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An optimal flattening algorithm for ship hull plate fabricated by Thermal Forming
Journal of Marine Science and Technology, 2018Co-Authors: Shuiming Zhang, Cungen Liu, Xuefeng WangAbstract:Normally, ship hull plates contain compound curvature distributions and they can only be fabricated by integrating mechanical rolling with bending and following them with regional heating to achieve required configuration. This paper mainly proposes a comprehensive flattening process to determine optimal planar shape, shrinkage strain distribution and mapping relation for three typical ship hull plates by Thermal Forming, which practically benefit for automatic Forming. An innovative geometric method is first presented to obtain initial planar approximation and strain square sum subject to negative principal strain constraints within each element from planar to desired surface is formulated based on nonlinear kinetic analysis. Then, we employ area equivalent method through transForming spatial quadrilateral into planar quadrilateral to simplify optimization model. Finally, initial planar approximations are regarded as iteration initial points to solve the model based on sequential quadratic programming. The results indicate that the proposed process can effectively achieve optimal planar shape, mapping relation and negative principal strain to help achieve all heating paths and heat source parameters at one time, thus automation.
Masahito Ueda - One of the best experts on this subject based on the ideXlab platform.
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Lightweight and anti-corrosive fiber reinforced thermoplastic rivet
Composite Structures, 2018Co-Authors: Masahito Ueda, Naoya Ui, Akio OhtaniAbstract:Abstract A lightweight anti-corrosive rivet is proposed using a fiber reinforced thermoplastic (FRTP) for the joining of carbon fiber reinforced plastic (CFRP). The FRTP rivet was fabricated via the braiding technique, where Glass fiber/PA66 commingled yarns were wrapped around straightly aligned Carbon fiber/PA66 commingled yarns. Using a pultrusion method, the braided yarn was consolidated into a FRTP rod, which was then cut to an appropriate length for use as a FRTP rivet. Quasi-isotropic CFRP laminates were joined by this rivet through a Thermal Forming process. Single-lap joint specimens were subjected to tensile tests, and compared with a bolted and blind-riveted joint. The joint strength increased with increasing fiber volume fraction of the FRTP rivet, which had a higher specific joint strength than the other metallic joints. The results revealed that, for the same joint strength, FRTP-rivet replacement of the metallic joint yields a reduction in the weight of the joint.
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Hybrid-fiber Reinforced Thermoplastic Rivet
2018Co-Authors: T. Takahashi, Naoya Ui, Masahito Ueda, A. OtaniAbstract:A lightweight anti-corrosive rivet is proposed using a fiber reinforced thermoplastic (FRTP) for the joining of carbon fiber reinforced plastic (CFRP). The FRTP rivet was fabricated via the braiding technique, where Glass fiber/PA66 commingled yarns were wrapped around straightly aligned Carbon fiber/PA66 commingled yarns. Using a pultrusion method, the braided yarn was consolidated into a FRTP rod, which was then cut to an appropriate length for use as a FRTP rivet. Quasi-isotropic CFRP laminates were joined by this rivet through a Thermal Forming process. Single-lap joint specimens were subjected to tensile tests, and compared with a bolted joint. The results revealed that, for the same joint strength, FRTP-rivet replacement of the metallic joint yields a reduction in the weight of the joint.
Ping Hu - One of the best experts on this subject based on the ideXlab platform.
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on the Thermal Forming limit diagram tfld with gtn mesoscopic damage model for aa7075 aluminum alloy numerical and experimental investigation
Journal of Alloys and Compounds, 2019Co-Authors: Liang Ying, Hai Rong, Ping HuAbstract:Abstract The formability of high strength AA7075 aluminum alloy under elevated temperatures is vital in guiding the fabrication of automobile structural parts. The ductile fracture Forming limit of AA7075 at elevated temperatures is essentially governed by Thermal damage evolution. In this paper, the hot tensile test (300oC-450 °C, strain rate 0.1s−1-0.001s−1) for AA7075 was conducted and the corresponding flow behavior was fitted by Hensiel-Spittel (HS) constitutive equation. The GTN mesoscopic damage model was implemented to take account of the damage evolution phenomenon of AA7075 at elevated temperatures. The temperature-dependent damage void volume fractions (VVF) were identified accurately based on a novel inverse identification procedure, named the CCD parameters design-FEM inverse simulation-genetic algorithm (CCD-FEIS-GA) optimization method. Subsequently, the Thermal Forming limit diagram (TFLD) was calculated based on the GTN damage parameters and further validated by hot Nakajima-type bulging experiment. The corresponding damage evolution behaviors and effects of critical Forming parameters were discussed in detail. The comparison of experimental and numerical results showed that the formability of AA7075 firstly increases and then decreases with the increasing Forming temperature, the TFLD0 reaches its maximum value when the temperature is 400 °C, and the formability also increases with the increasing strain rate and the decreasing surface coefficient of friction. The proposed simulated strategy coupled with mesoscopic GTN approach conduces to the accurate prediction of TFLD and damage fracture behavior of AA7075 in the hot Forming process.
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Thermal Forming limit diagram tfld of aa7075 aluminum alloy based on a modified continuum damage model experimental and theoretical investigations
International Journal of Mechanical Sciences, 2019Co-Authors: Hai Rong, Liang Ying, Ping Hu, Jinghuang ZhangAbstract:Abstract The formability of high strength Al-Zn-Mg-Cu (7000 series) aluminum alloys can be significantly improved at elevated temperatures, which has been paid more attention in recent decades. The formability of high strength aluminum alloys at elevated temperatures is essentially governed by Thermal-damage evolution. In this paper, the main purpose is to propose a modified continuum damage model to describe the damage evolution and predict the fracture behavior of AA7075 at elevated temperatures (300–400 °C). Firstly, the Thermal-mechanical behavior and Forming limit of AA7075 alloy sheet were experimentally investigated using a series of isoThermal uniaxial tensile tests and Nakajima tests at different temperatures and strain rates. A set of uniaxial continuum damage constitutive equations (CDCEs) coupling continuum damage mechanics (CDM) with unified viscoplastic theory was proposed to describe the uniaxial tensile behavior of AA7075. Subsequently, the uniaxial equations were extended into a set of multi-axial CDCEs by introducing a multi-axial damage correction formula to predict the TFLD of AA7075. Besides, the forward Euler method was employed to integrate the proposed CDCEs, and the corresponding material constants of CDCEs were further calibrated by the non-dominated sorting genetic algorithmⅡ(NSGA-Ⅱ). The results illustrate that the Thermal flow behavior and the TFLD of AA7075 alloy can be predicted successfully by the proposed damage model. Detailed discussions about the effects of corresponding parameters on the computed TFLD indicate the established multi-axial CDCEs are flexible and beneficial to the application potential in numerical simulation of hot sheet metal Forming.