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Leigang Li - One of the best experts on this subject based on the ideXlab platform.

  • digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Jin Guo-liang, Leigang Li
    Abstract:

    Abstract A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction.

  • Digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Xiang Guo, Jin Guo-liang, Leigang Li
    Abstract:

    A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction. © 2013 Elsevier Ltd.

Hao Hu - One of the best experts on this subject based on the ideXlab platform.

  • digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Jin Guo-liang, Leigang Li
    Abstract:

    Abstract A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction.

  • Digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Xiang Guo, Jin Guo-liang, Leigang Li
    Abstract:

    A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction. © 2013 Elsevier Ltd.

Zhengzong Tang - One of the best experts on this subject based on the ideXlab platform.

  • digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Jin Guo-liang, Leigang Li
    Abstract:

    Abstract A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction.

  • Digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Xiang Guo, Jin Guo-liang, Leigang Li
    Abstract:

    A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction. © 2013 Elsevier Ltd.

Jin Guo-liang - One of the best experts on this subject based on the ideXlab platform.

  • digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Jin Guo-liang, Leigang Li
    Abstract:

    Abstract A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction.

  • Digital speckle based strain measurement system for Forming Limit Diagram prediction
    Optics and Lasers in Engineering, 2014
    Co-Authors: Hao Hu, Zhengzong Tang, Xiang Guo, Jin Guo-liang, Leigang Li
    Abstract:

    A digital speckle based strain measurement system is developed to investigate the Forming Limit Diagram (FLD) of sheet metal. A stochastic speckle pattern is sprayed on the surface of flat sheet metal before Forming. A series of images are recorded by two cameras during the Forming process. The strain field is then calculated for FLD determination, which involves the following key issues. First, to solve the problem of large deformation and strain measurement in sheet metal Forming, a fractionized matching algorithm using deformation continuity of adjacent images is proposed. Second, an algorithm for three-dimensional (3-D) strain calculation is discussed, and a spline model is specially used to calculate the strain of the sheet metal in deep drawing. Third, a Limit strain determination algorithm is proposed for Forming Limit curve (FLC) calculation by creating sections in the measured strain fields. Finally, a Forming Limit strain measurement system (also called Xi'an Jiaotong University Forming Limit Curve measurement system, XJTUFLC) is developed on the Visual Studio 2010 platform. With our self-developed image acquisition instrument and sheet metal bulging setup, FLD determination tests are conducted to validate the performance of the system. And the measured FLD is compared with the traditional experimental FLD as well as with that predicted by the empirical model. From the analysis of the experimental results, it can be concluded that the proposed system is feasible to measure the full-field strain during sheet metal Forming processes and provides a better solution for Forming Limit Diagram prediction. © 2013 Elsevier Ltd.

Suwat Jirathearanat - One of the best experts on this subject based on the ideXlab platform.

  • experimental and theoretical formability analysis using strain and stress based Forming Limit Diagram for advanced high strength steels
    Materials & Design, 2013
    Co-Authors: Sansot Panich, Frederic Barlat, Vitoon Uthaisangsuk, Surasak Suranuntchai, Suwat Jirathearanat
    Abstract:

    Abstract In this study, experimental and numerical analyses of Forming Limit Diagram (FLD) and Forming Limit Stress Diagram (FLSD) for two Advanced High Strength Steel (AHSS) sheets grade DP780 and TRIP780 were performed. Initially, the Forming Limit curves were experimentally determined by means of the Nakazima Forming test. Subsequently, analytical calculations of both FLD and FLSD were carried out based on the Marciniak–Kuczinsky (M–K) model. Additionally, the FLSDs were calculated using the experimental FLD data for both investigated steels. Different yield criteria, namely, von Mises, Hill’s 48, and Barlat2000 (Yld2000-2d) were applied for describing plastic flow behavior of the AHS steels. Both Swift and modified Voce strain hardening laws were taken into account. Hereby, influences of the constitutive yield models on the numerically determined FLDs and FLSDs were studied regarding to those resulted from the experimental data. The obtained stress based Forming Limits were significantly affected by the yield criterion and hardening model. It was found that the Forming Limit curves calculated by the combination of the Yld2000-2d yield criterion and Swift hardening law were in better agreement with the experimental curves. Finally, hole expansion tests were conducted in order to verify the different failure criteria. It was shown that the stress based Forming Limit curves could more precisely describe the formability behavior of both high strength steel sheets than the strain based Forming Limit curves.