Material Testing for Development and Calibration of Material models for Plastic Deformation and Failure
Material testing at various, loading conditions, temperatures, and strain rates is used forstudying plastic deformation and failure of materials. The data from such tests is used for developing and calibrating material model that are utilized in numerical codes that are used for simulations of practical applications. The presentation will review experimental techniques used in such testing with emphasis on the integration of Digital Image Correlation (DIC) for measuring full-field deformations and the development of new tests. Of special interest is the testing needed for supporting the new deformation and failure model MAT224 in LS-DYNA ® . This material model is based on experimental determination of a failure surface that gives the equivalent plastic strain to failure as a function of stress triaxiality and the Lode parameter. It is done by testing specimens that are subjected to uniform and nonuniform states of stress and deformation and determining the failure state (deformation and stress) from matching the simulation of the test with the DIC and load measurements. Testing can be done at room temperature or, by using a special furnace, at elevated temperatures (up to 850C°). In addition, a new experimental setup in which full-field deformation and full-field temperature are measured simultaneously on the surface of a specimen during a tensile test is introduced. Results from testing specimens made of stainless steel show a significant temperature increase in the neck area in a quasi-static tension test. In most material models (e.g. Johnson Cook) the effect of strain hardening and temperature softening are uncoupled. The data that is typically used for determining the parameters in the models is obtained from experiments where strain hardening and temperature are coupled. The results from the new experimental setup can be used for uncoupling the effect of strain hardening and thermal softening during plastic deformation.
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Material Testing for Development and Calibration of Material models for Plastic Deformation and Failure
Material testing at various, loading conditions, temperatures, and strain rates is used forstudying plastic deformation and failure of materials. The data from such tests is used for developing and calibrating material model that are utilized in numerical codes that are used for simulations of practical applications. The presentation will review experimental techniques used in such testing with emphasis on the integration of Digital Image Correlation (DIC) for measuring full-field deformations and the development of new tests. Of special interest is the testing needed for supporting the new deformation and failure model MAT224 in LS-DYNA ® . This material model is based on experimental determination of a failure surface that gives the equivalent plastic strain to failure as a function of stress triaxiality and the Lode parameter. It is done by testing specimens that are subjected to uniform and nonuniform states of stress and deformation and determining the failure state (deformation and stress) from matching the simulation of the test with the DIC and load measurements. Testing can be done at room temperature or, by using a special furnace, at elevated temperatures (up to 850C°). In addition, a new experimental setup in which full-field deformation and full-field temperature are measured simultaneously on the surface of a specimen during a tensile test is introduced. Results from testing specimens made of stainless steel show a significant temperature increase in the neck area in a quasi-static tension test. In most material models (e.g. Johnson Cook) the effect of strain hardening and temperature softening are uncoupled. The data that is typically used for determining the parameters in the models is obtained from experiments where strain hardening and temperature are coupled. The results from the new experimental setup can be used for uncoupling the effect of strain hardening and thermal softening during plastic deformation.
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