摘要
考虑残余应力对压痕弯曲梁应力场强度的贡献后,对相应的K_(IC)表达式进行了修正。研究表明:在合适的压痕压制荷载范围内,弯曲梁强度σ_r与压痕裂纹深度的倒数平方根(1/a)^(1/2)之间存在线性关系;压痕处的残余应力效应可以用σ_(?)-(1/a)^(1/2)直线关系式中的强度修正项加以描述。高温下强度修正项的值随温度的升高而减小,说明残余应力在高温作用下得到了部分消除;退火处理也导致了强度修正项的减小。采用强度修正项后的K_(IC)计算公式,压痕弯曲梁法可望应用于各种温度下的K_(IC)测试;由σ_(?)(1/a)^(1/2)直线斜率求得的K_(IC)值不受残余应力影响。
An improved K_(IC) formula for indented bending beam method is proposed by considering the contribution from residual stress to the total stress intensity at the indentation flaw. Ir'is shown that a quite linear relationship exists between the strength of bending beam,σ_f, and the inverse square root of the depth of indentation flaw,(1/a)^(1/2) for an appro-priate range of indentation load. The effect of residual stress about indentation canbe described properly with a strength revisionary term appeared in σ_(1/a)^(1/2) fitting equation. The value of strength revisionary term decreases as temperature increases, inflecting that the residual stress is relieved partly at elevated temperatures.Annealing process also results in decrease in the value of revisionary term. Experiment confirms that indented bending beam method can be used for K_(IC) measurement at both room and elevated temperatures. The residual stress does not influence K-(IC) value calculated from the slope of σ_(1/a)^(1/2) fitting line.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
1991年第3期226-233,共8页
Journal of The Chinese Ceramic Society
关键词
陶瓷
断裂韧性
压痕
应力
fracture toughness
indentation
residual stress
ceramic materials
