基于Normalized Cockcroft & Latham韧性损伤准则Ti600合金临界损伤值的测定

采用物理实验与数值模拟相结合的方法确定材料在给定条件下的临界损伤值,进行Ti600合金1010℃,0.001s^-1下的拉伸实验,获得该条件下的真实应力-应变曲线。同时简化Normalized Cockcroft&Latham损伤模型,以真应变ε1代替等效应变ε-,极限拉应力σUTS代替等效应力σ-,计算得到高温钛合金Ti600在该条件下的临界损伤值。将此损伤值嵌入有限元软件中,对之前的拉伸过程进行数值模拟验证,以确定该临界损伤值的准确性。结果表明:Ti600合金在1010℃,0.001s^-1下的临界损伤值为0.643。将其代入有限元软件模拟拉伸过程发现,试样裂纹萌生和扩展位置预测准确,最小横截面变化规律与实验基本相符。这说明基于Normalized Cockcroft&Latham模型和拉伸实验测得的Ti600临界损伤值是较准确的。

Determination of critical damage value of Ti600 alloy based on Normalized Cockcroft & Latham ductile fracture criterion

Critical damage value of material was obtained by physical experiment combined with a finite element software.True stress-strain curve of Ti600 alloy was studied by high temperature tensile test at 1010℃ and 0.001s^-1.A simplified Normalized Cockcroft & Latham ductile fracture criterion was used,in which ε- and σ- were substituted by ε 1 and σ UTS,respectively.The critical damage value of Ti600 alloy on the above experimental condition was calculated and then was embedded in a finite element software to verify its accuracy by analysing high temperature tensile process.The result shows that the critical damage value of Ti600 alloy at 1010℃ and 0.001s^-1 equals 0.643.By the finite element analysis,the crack initiation and propagation are predicted well and computational variety law of minimum cross sectional area is basically agreed with the experimental law.Hence,the critical damage value of Ti600 alloy obtained by combining a Normalized Cockcroft & Latham ductile fracture criterion with a finite element software is fairly precise.