初始损伤影响钢的低温解理断裂韧性的细观力学分析  

Meso-scopic mechanical analysis of effect of initial damage on cleavage fracture toughness of steel at low temperature

作　　者：王国珍[1] 马进[1] 杨伟顺[1] 陈剑虹[1] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,甘肃兰州730050

出　　处：《兰州理工大学学报》2006年第3期29-33,共5页Journal of Lanzhou University of Technology

摘　　要：通过长条形孔洞附近的局部应力应变分布的细观有限元模拟计算,对初始损伤影响钢的低温解理断裂韧性的原因进行了研究.计算结果表明,预加载时引入的长条形孔洞缺陷在后续低温加载时,其前端产生了局部高应力应变集中,促使了解理裂纹的形核(pε≥pεc)和扩展(yσy≥fσ),使解理发生在较低的载荷下,引起了韧性的降低.随预载荷比P0/Pgy的增加,材料中的损伤量和损伤孔洞的尺寸增大,引起的局部高应力应变集中程度增大,可促使解理发生在更低的载荷下.这就是随着预载荷比P0/Pgy的增加,材料的缺口解理断裂韧性Pf/Pgy降低的细观力学原因.The origin of effect of initial damage on the cleavage fracture toughness of steel at low temperature was investigated by means of meso-scopic FEM analysis for the local stress and strain distribution around large string cavities. The calculation result showed that, during loading at low temperature, a high local stress and strain concentration was produced ahead of large string cavities induced originally by preload. This high local stress and strain concentration promoted nucleation （εp≥εpc） and propagation （σyy≥σf） of cleavage fracture, and made both the fracture load and toughness low. With increasing the pre-load ratio Po/Pgy, the damage amount and the cavity size increased, which caused higher local stress and strain concentration and lower fracture load. This is the meso-scopic mechanical reason for the decrease of the notch cleavage fracture toughness with increasing the Po/Pgy.

关 键 词：初始损伤 断裂韧性 有限元分析 应力 应变 钢 

分 类 号：TB301[一般工业技术—材料科学与工程]