Calibration of a constitutive model for polycrystalline diamond sintering process

Polycrystalline diamond is mostly pressed at high temperature in actual production. Thus, circumferential strain data of powder moulding are difficult to collect at high temperatures. As a result, the parameters of DPC constitutive model cannot be obtained using conventional testing methods. Moreover, the use of conventional equipment to test the mechanical properties becomes challenging because of the extremely high hardness and compressive strength of polycrystalline diamond. Sintering tests of polycrystalline diamond were carried out at 1360 degrees C and 223 Mpa using the spark plasma sintering (SPS) method, and displacement-load data were obtained. The spark plasma sintering experiment of polycrystalline diamond under high temperature and pressure was carried out using the Drucker Prager/Cap (DPC) model with relative density to obtain accurate displacement and load numbers. Combined with USDFLD subroutine, the experiment of polycrystalline diamond sintering was simulated on ABAQUS. Based on the complex method, ABAQUS-MATLAB platform is used for the reverse identification of constitutive parameters. The constitutive model parameters of polycrystalline diamond sintering process are obtained. This approach can describe the mechanical behaviour of polycrystalline diamond powder in the sintering process. In addition, the inverse identification method of the constitutive model in the sintering process of polycrystalline diamond based on ABAQUS and MATLAB solves the problem on the difficulty to observe the sintering of polycrystalline diamond under high temperature and high-pressure environment. Moreover, the constitutive model parameters of the sintering process are obtained, thereby reducing the cost and condition constraints in the actual experiment. A novel technique involves obtaining powder constitutive parameters at high temperature from the sintering point of view. This approach is important to simulate sintering of polycrystalline diamond and its composite products. Foundation item: National Natural Science Foundation of China (Grant No. 52075438), the Key Research and Development Program of Shanxi Province of China (Grant No. 2020GY-106), the Open Project of State Key Laboratory for Manufacturing Systems Engineering (Grant No. sklms2020010), and the Open Research Fund of Key Laboratory of Oil & Gas Equipment of Ministry of Education (Grant No. OGE201702-110).