Study On The Compressibility Of Korshinsk Peashrub And Its Stress Relaxation Characteristics

In this paper, as the research object, the compressibility and stress relaxation characteristics of Korshinsk Peashrub crumbled were studied and the main factors that impacted them were analyzed to obtain the law of the compressibility and stress relaxation characteristics. Then, based on vvirtual prototyping technology and finite element method, Korshinsk Peashrub's compressibility and stress relaxation characteristics were simulated .The main contents of this study and the results achieved were as follows:1) Viewing temperature as the research factor, the compressibility of Korshinsk Peashrub crumbled was studied with self-developed compression device on which the temperature could be changed. The results showed that the compressed process can be divided into two stages: loose and compressed.In the process the functions between the pressure and compressed density as well as between the bulk modulus and compressed density were separately obtained.With viscoelastic theory, the nonlinear rheological model that described the compressed process was established and the correctness of the model was verified with the validation tests.2) With the single-factor experiment, based on material temperature, moisture content and feeding capacity, the multi-factor orthogonal experiment was carrired out . The results showed that the compressibility increased with the increase of temperature and moisture content and decreased with the reduce of feeding amount. With the range analysis and the variance analysis, the primary and secondary sequence that impacted on the experiment results by temperature, moisture content and feeding rate and the law of the interaction between factors were obtained.3) Based on virtual prototype technology, the simulation model of the Korshinsk Peashrub's compressed process was built with the ADAMS software.Using spline function to impose pre-load and drive, the simulation of the whole compressed process was achieved.The model validation results showed that the simulation model can simulate better the stress - strain relationship during the compressed process.4) With the temperature and compressed density factors, the stress relaxation experiments of Korshinsk Peashrub crumbled were carried out. The results showed that there were two obvious phases in the stress relaxation process: the stress dropped rapidly in the initial stage; the decline rate of the stress changed slowly and ultimately tended to remain unchanged. The stress relaxation characteristics were influenced by temperature: when the temperature increased, the stress relaxation time decreased and vice versa. Then, based on visco-elastic theory, the stress relaxation models and constitutive equations were established with model theory and empirical models.5) Based on the finite element method, the stress relaxation law of the Korshinsk Peashrub compressor and the variation law of the internal displacement and node force of each node were simulated using the ANSYS software. The results showed that with the initial stress relaxation model the node density at center was greater, the one at circumference was relatively lower, while in the latter of the relaxation law it was opposite.The node axial force and radial force decreased with the time increased and the change rate of the node stress at the center was less than that at the circumference. Meanwhile, the total node counterforce on the side wall of the model reduced gradually and in the early stages of relaxation the node counterforce changed drasticly, then the node counterforce changed slowly, which was similar to the axial stress relaxation law describled in this paper.