Experimental Research And Numerical Simulation Of Compression And Fragmentation Of Quartz Glass Sphere

In this thesis,the static compression fragmentation experiments of quartz glass spheres and the experiment of quartz glass spheres impacting a rigid target at different impact velocities were carried out.At the same time,the numerical simulation of the experimental process were carried out by using discrete element code PFC^3D,the crushing process and different fracture modes of glass spheres were analyzed.Static compression experiments of quartz glass spheres with diameter of 10mm by MTS universal testing machine.Experiments show that the compression and fracture of quartz glass spheres are staged,and eventually“explosive”fragmentation occurs.According to the maximum broken load by the experiment,the critical breaking velocity of the sphere can be calculated and verified by impact test and numerical simulation.High-speed air gun was used to carry out the experiment of quartz glass balls impacting on a rigid target plate with the same size.It was verified that the critical destruction velocity of the quartz glass ball at a diameter of 10mm was about 14 m/s.Experiments shows that quartz glass spheres have different failure modes at different velocities.With the increase of the impact velocity,the failure modes such as elastic collision,local failure,splitting damage,collapse failure,and spallation failure occurs in sequence.The above experimental processes were numerically simulated by the discrete element code PFC^3D.The simulation results are in good agreement with the experimental phenomena.The compression force in the simulation is consistent with the experiment.According to the compressive force of ball crushing,the crushing of the quartz glass balls can be divided into three stages:“elastic compression-partial crushing-blasting crushing”.The formation of micro cracks inside the sphere at each stage is analyzed.The cracks are mainly concentrated in the“explosion”fragmentation stage.The simulation results shows that under the critical breaking velocity,the ball rebounds from the rigid wall slightly below the impact velocity;at low speed,three regions of“compression and fragmentation zone-surface spalling zone-shear failure zone”are formed in order from the impact end.When velocity is slightly higher,due to the expansion of the shear failure zone,the sphere eventually breaks into several pieces resembling a“crescent”;at medium speed,the quartz glass ball is“collapsed”;at high speed,the inside of the sphere tensile crack occurs and a spallation failure occurs.By analyze the impact force,the impact velocity and the formation of internal cracks in the sphere,the crushing of the quartz glass sphere can be divided into three stages:“elastic compression-integral fracture-secondary impact”,and the fragmentation of each stage was analyzed.The fragments generated in the simulation were statistically analyzed.It was found that the fragments conformed to the two-parameter Weibull distribution,and the extent of fragmentation of the sphere can be quantified by two Weibull parameters.The simulation results of the quartz glass ball obliquely impact rigid wall shows that the impact velocity of the sphere can be decomposed into the vertical impact velocity and parallel velocity.The crushing of the sphere is mainly determined by the vertical impact velocity.In the elastic range,the parallel velocity does not affect the destruction of the sphere.For the inelastic collision,the parallel velocity can weaken the extent of fragmentation of the sphere.The compression crushing experiment of quartz glass sphere can qualitatively analyze the crushing process of quartz glass sphere.The numerical calculation can quantitatively study the crushing mechanism of the sphere.The combination of the two provides a convenient means for studying the damage characteristics of brittle materials.In-depth study of impact crushing of brittle materials offers the possibility.