Simulation And Experimental Study On Micro Fracture Mechanism Of Granite

With the application of the computer technology,the granite cutting has been widely used in the daily life,and it also has a wider application prospect.At present,machinery and equipment technology of granite processing has been mature,but the processing efficiency and material loss has become a difficult problem of granite machining.The processing parameters are selected by experience.The improper processing parameters often lead to wear cutting-tool,waste material and reduce the processing quality and efficiency.The key factor affecting the efficiency of granite processing is the formation of debris,and the wear of the tool has a great influence on the machining efficiency.In the granite processing field,there is a lot of research on the granite cutting and crushing,so there are many experimental studies on diamond saw blade,which can provide reference for the granite cutting process.However,the research on the micro cracks in the processing of granite is lack,which makes it difficult to develop in the processing of granite.Therefore,this thesis is aimed at the process of indentation,which the crack was caused by the contact of diamond grains and granite in the granite processing.It was discussed from the following aspects:First of all,through consulting a large number of documents,the theoretical basis of the performance of stone material and stone indentation experiments were sorted out,and the indentation fracture mechanism of general stone in different pressure head was summarized.Through this mechanism,this thesis analyzed the contact stress and the crack formation process of the granite with the pressure head and the working condition.On the basis of the theory of fracture mechanism,a further study was carried out.According to the analysis of granite stone indentation stress state is based on the theoretical study of early stone in indentation test of stress field.In the stress field,the formation of an irreversible deformation zone was formed in the stress field,and the expansion of various cracks was described in detail from loading to unloading process.A radial crack model of granite under the reference pressure head was studied.The cracking behavior of rock under the pressure head was studied based on the yield criterion.The stress state of different regions in the model was analyzed.The relationship between the crack length and the load and the indentation depth was deduced according to the theory.Secondly,this thesis used ANSYS/LS-DYNA and LS-PrePost software to simulate the indentation.The material model was suitable for the simulation process.The selection of the material model and granite stone was the basis of the simulation process,which directly influences the validity of the simulation results.Through simulation,it simulated the diamond particles in the pressing process of crack producing granite and the crack growth process was analyzed in detail,and the theoretical process is compared with that of the process.It reached the indentation of different granite by modifying the material parameters.The stress change of granite in the process of indentation was obtained by different linear velocity,and the stress state of the crack formation and propagation process and granite was obtained under different working conditions,and the radial crack size was measured under different line speeds.In the end,the indentation test of the sharp pressure head was carried out using the micro hardness tester and the micro observation system.The indentation process was achieved by means of micro hardness tester.In the experiment,the test force and the time of holding pressure were set up.This thesis extended observation radial indentation granite surface by a 3-D microscope system,the influence of the crack length on the crack growth was measured under different operating conditions.The relationship between the cutting force and the length of the crack was obtained by the simulation.Through the above work,the stress state of granite and the indentation test were compared.The simulation results were verified by the experimental process,and the stress state and the radial crack size were compared.It has certain directive significance to reduce production cost and improve the processing efficiency in granite processing from the theoretical data of simulations and experiments.