A geometric model of rotors is established on the basis of the structure of vertical shaft impact crusher. The dynamic simulation of the rotor is carried out by using the discrete element software EDEM. At the same time, the correlation between the angle of the guide plate and the crushing performance of the crusher is studied systematically. The optimal angle of the guide plate is obtained by theoretical analysis of the particle motion. The simulation method is used to analyze the velocity of particles, so the influence law of the angle of the guide plate on the acceleration effect of particles is obtained. The results of this paper show that the peak value of the maximum velocity of particles is the highest when the angle of the guide plate is 35 ° , which is consistent with the theoretical results. At this time, the average velocity of particle population is the largest and the proportion of particles with high velocity is the highest. It means that the particles obtain the largest crushing kinetic energy and the best crushing performance.
At present, the demand for ready-mixed concrete (RMC) in construction industry is increasing day by day, and the supply mode of multiple delivery depots corresponding to multiple construction sites has been widely used. In order to further improve the joint distribution efficiency between various delivery depots, this research establishes a multiobjective optimal distribution model with time window constraints and demand postponement attributes for the problem that the subbatching plants need to work together. The model divides the reasons for demand postponement into two types: the constraint for timely unloading of trucks cannot be met on time and the constraint for timely pouring at the construction site cannot be met on time. This work improved the coding method of genetic algorithm based on the characteristics of the distribution model. Using hierarchical real-coding form, the coding operator of each layer can be evolved separately, which ensures the globality of the search, and, at the same time, an improved immune operator is added to ensure the local search performance. By comparison, the results obtained by improved GA are 7.05% higher than those of the standard GA, and the early convergence speed of improved GA is obviously better than that of the standard GA. The simulation experiments show that the total trucks’ waiting time during the process of providing delivery services from 5 concrete plants to 8 construction sites is 769 minutes, and the total waiting time of 8 construction sites is 507 minutes. Through practical case analysis, this work can enable RMC production enterprises and construction sites to effectively reduce the waiting time of corresponding operations, and the obtained results are close to the simulation results. The proposed method indeed improves the efficiency of RMC distribution.
During the sand-making process, the wear of the split cone will affect the dynamic balance of the rotor and the sand-making effect of the crusher. This paper focuses on experiments and simulations with the rotor of a vertical shaft impact crusher. A wear model for predicting the wear value of the split cone is established and its effectiveness is verified. The orthogonal test of L 16 4 4 is designed. By using the range analysis method, the influence of the rotor speed, the feed height, the installation angle, and the number of the guide plate on the wear resistance of the split cone are studied. By using the multiple linear regression analysis method, the optimal parameter combination of each factor is obtained. The results of this paper show that the wear resistance of the split cone is the best when the installation angle of the guide plate is 40°, the installation number of the guide plate is 3, the rotor speed is 2800 r/min, and the feed height is 40 mm.
Nonlinear random response and fatigue life estimation of the skin panels of hypersonic flight vehicles at elevated temperatures and high intensity acoustic loadings have become a matter of considerable importance in recent years. Finite element equations are presented for the prediction of nonlinear responses of curved panels under combined thermo-acoustic loadings. Thermal loading with a non-uniform temperature field is considered, and band limited Gaussian white noise is chosen as random acoustic loading. A numerical integration is applied to determine random response. Thermal buckling temperature and thermal buckling deflections are obtained to explain the snap-through phenomenon. The modal frequency of the vibration about the thermally buckled equilibrium position is studied, which shows great difference between the primary and secondary buckled equilibrium position of curved panels. Displacement and stress response obtained show nonlinear characteristics of curved panels under thermo-acoustic loadings. Stress-life (S-N) curves and rainflow counting method are combined by means of damage accumulation theory and mean stress model to predict curved panel fatigue life. The results show that the fatigue life estimation of the curved panel by using the Smith-Watson-Topper model is more conservative.
The three-dimensional model rotor of vertical shaft impact crusher was established by using the three-dimensional software Solidworks and it was imported into the discrete element software EDEM for dynamic simulation. The force of the split cone, the motion trajectory and force of the particles were analyzed in rotor by using the post-processing function of EDEM. The results show that the split cone was mainly affected by the normal action of particles. According to the definition of impact wear, it was finally determined that the wear form of the split cone is impact wear.
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