基于HyperMesh 和LS-DYNA 的玉米籽粒碰撞损伤动态过程的有限元分析
摘要
This study focuses on exploring the damage susceptibility and the realistic representation of time dependent nonlinear mechanical behaviour of maize kernel under various impact cases with threshing unit. A reverse engineering approach based on three dimensional (3D) scanning technology, finite element method (FEM)-based explicit dynamics simulations and response surface method (RSM) were utilized to investigate contact force, Von Mises stress and displacement characteristics, determine critical velocity of maize kernel. Five moisture contents (11.78%, 17.63%, 23.45%, 29.31% and 34.73%) and five impact velocities (4, 6, 8, 10 and 12 m/s) were considered in the impact simulation scenarios. Useful numerical data and deformation visuals were obtained from the simulation results. These results showed that when impacting, the stress concentrated in the small contact area and spread around and decreased gradually. The maximum contact force, maximum Von Mises stress decreased while maximum displacement increased as the moisture content increased, and the critical velocities of maize kernels with moisture contents of 11.78%, 17.63%, 23.45%, 29.31% and 34.73% were determined as 5.51, 6.75, 8.15, 9.36, 10.57 m/s, respectively. In addition, prediction models were successfully established with reasonable coefficient of determination (R<sup>2</sup>) values. The best parameter combination was obtained through multi-objective optimizing as moisture content of 26.99% with impact velocity of 5.17 m/s, and the corresponding contact force, Von Mises stress and displacement were calculated as 19.30 N, 40.64 MPa and 0.73 mm, respectively. Verification checks of the prediction models also indicated that the relative errors between the results of simulation and the empirical model were less than 8%. The above results suggest that these models are reliable to describe the damage susceptibility of the maize kernel for various impact cases.