扭速对脆性材料强度和剪切模量的影响分析

Analysis of the Influence of Torsional Velocity on the Strength and ShearModulus of Brittle Materials

以脆性材料为研究对象,通过扭转试验研究扭转速率对脆性材料的扭转强度和剪切模量的影响.首先对脆性材料发生扭转时表面的应力状态进行分析,通过扭断后不同的断口形态来判断断裂的原因;然后以脆性材料的典型代表材料铸铁试件进行分组扭转试验,得到不同扭转速率下铸铁试件的扭矩图和扭转数据;最后对其扭转强度和剪切模量进行分析,得出结论:当扭转速率从小开始增加时,由于在弹性范围内,材料仍具有弹性可以承受较大形变不会被破坏,因此剪切强度极限和剪切模量都会增加.然而当扭转速率超过了材料所能承受的弹性极限,材料就会变形而失去弹性,从而导致剪切强度极限和剪切模量减小.

Taking brittle materials as the research object,the influence of torsion rate on the torsional strength and shear modulus of brittle materials is studied through torsion tests.Firstly,analyze the surface stress state of brittle materials when they undergo torsion,and determine the cause of fracture through different fracture morphology after torsion;Then,typical representative materials of brittle materials,cast iron specimens,were subjected to grouped torsion tests to obtain torque diagrams and torsion data of cast iron specimens at different torsion rates;Finally,an analysis was conducted on its torsional strength and shear modulus,and the conclusion was drawn that when the torsional rate increases from a small point on,the material still has elasticity within the elastic range and can withstand large deformations without being damaged.Therefore,the ultimate shear strength and shear modulus will both increase.However,when the twisting rate exceeds the elastic limit that the material can withstand,the material will deform and lose its elasticity,which will lead to a decrease in the shear strength limit and shear modulus.