U形切槽梁的应力集中系数及材料测试新方法

Stress Concentration Factors for Beams with Single Side U-shaped Notch Subjected to Pure Bending and a New Method for Mechanical Test of Quasi-brittle Materials

用有限元分析得到单边U形切槽梁纯弯曲的应力集中系数,该应力集中系数随切槽宽度增加而急剧减小;随切槽深度增加先增加而后减小,最大值发生在切槽深度与梁高之比α=a/h=0.2附近,改进和扩展了现有应力集中系数手册中的有关数据。另外对U形切槽梁承受三点弯曲的应力集中系数在深切槽段即无量纲化切槽深度α=0.8~1.0也补充了相应数据。基于利用本文得到的U形切槽梁应力集中系数值,提出采用变化切槽根部圆角半径的纯弯曲或三点弯曲U形切槽梁,同时测试准脆性材料拉伸强度σt和断裂韧度KIC的一种新方法。

The stress concentration factors for pure bending of beams with single side U-shaped notch are derived using finite element analysis, with increasing notch depth, the stress concentration factors first increase then decrease, and with increasing notch width, the stress concentration factors decrease drastically, the maximum values occur when the ratio of notch depth to beam height is nearα = α/h = 0.2, the derived results improve and supplement the stress concentration factors collected in the existing handbooks. Data of stress concentration factors are also supplemented for the same U-shape notched beam of deep notch section, i.e. α = 0.8 - 1.0, and subjected to three-point bending. Based on using the stress concentration factors for the U-shape notched beam obtained, a method for simultaneously testing quasi-brittle material＇s tensile strength and fracture toughness using pure bending or three-point bending beams with single side U-shaped notch of different notch root radius is suggested.