High Temperature Dynamic Mechanical Performance Analysis Of Fused Silica And Experimental Research On Laser Assisted Cutting

Fused silica is mainly an amorphous solid composed of 99.9999% pure SiO2,which has excellent physical,chemical,mechanical and optical properties.These excellent characteristics make fused silica widely used in aerospace,high-power lasers and precision instruments.However,the high brittleness and low toughness characteristics of its conventional state make it difficult to process by traditional methods.For example,grinding will cause micro-crack damage on the surface and subsurface,and cutting will cause severe tool wear.Laser assisted cutting is to use a heat source to reduce the strength of the material in a very short time,and to convert the brittleness removal mode of the material to the plastic removal mode,thereby obtaining a better machined surface quality and longer tool life.In this paper,the following researches are carried out on the high-temperature dynamic mechanical properties and laser-assisted cutting performance of fused silica :First,this paper carried out static tensile experiments of fused silica at room temperature and high temperature,and analyzed the effect of temperature on the mechanical properties of the material.The experimental results showed that the tensile strength of fused silica at1400℃ decreased by about 93.1% compared to room temperature,the modulus of elasticity decreased by 92.1%,and at the same time,a thermo-mechanical damage model of the material was established according to the statistical distribution law of the tensile strength of the material.Secondly,the SHPB dynamic mechanical performance experiment of fused silica was carried out,and the effect of temperature and strain rate on the dynamic compressive strength of the material was analyzed.The study found that the dynamic strength of the material at1000℃ is about 1/3 of that at 23℃.The dynamic compressive strength at a strain rate of1800/s is about 1.5 times that at 800/s;the failure mode of the material changed from the axial splitting under low strain rate to the crushing failure under high strain.Lastly,the JC constitutive equation was initially established,and the SHPB impact performance of the material was verified by simulation using this JC model.Finally,the SPH orthogonal cutting simulation was carried out using the above constitutive equations,and the dynamic cutting process,cutting force and surface topography change laws of the material under conventional and laser assisted cutting were analyzed.Besides,a laser assisted cutting experiment was carried out,focusing on the effect of laser power on the cutting performance of materials.Compared with the conventional cutting,laser assisted cutting reduced the cutting force by up to about 63.5%,and the quality of the machined surface was improved by about 66.35%,and it could produce a smaller tool wear and a longer tool life.