LC4CS铝合金三维复合型断裂的试验研究  

THREE-DIMENSIONAL MIXED MODE FRACTURE EXPERIMENTAL INVESTIGATION OF LC4CS ALUMINIUM ALLOY

作　　者：董蕙茹[1] 郭万林[1] 徐绯[1] 

机构地区：[1]西安交通大学机械结构强度与振动国家重点实验室

出　　处：《机械强度》2003年第2期222-226,共5页Journal of Mechanical Strength

基　　金：国家杰出青年科学基金资助项目 (5962 551 0 )~~

摘　　要：设计并完成LC4CS铝合金 2mm、4mm、8mm、14mm等四种不同厚度紧凑拉伸试样的Ⅰ +Ⅱ复合型断裂试验 ,得到各个厚度下不同加载条件时不同加载条件的载荷位移曲线和裂纹起裂角。结果表明试样厚度和载荷复合比对试样的承载能力、裂纹起裂角均有明显影响 ,纯Ⅰ型载荷下薄试样的承载能力好于厚试样 ;Ⅰ +Ⅱ复合载荷条件下 4mm的承载能力最大 ,2mm和 8mm接近 ,14mm最小 ;纯Ⅱ型载荷条件下各厚度的承载能力基本一致。 2mm试样的起裂角值与 14mm试样的值很接近 ,4mm试样的值略高 ,8mm试样的值低得多。基于平面假设基础上的最大周向应力准则能够很好地预测 2mm薄试样和 14mm厚试样的裂纹起裂角 ,但预测 8mm中间厚度时误差很大。此结果为建立三维复合型断裂准则提供必要的试验基础。Systematic mixed mode Ⅰ+Ⅱ fracture experiments on LC4CS Aluminium alloy compact-tension-shear (CTS) specimens of 2?mm,4?mm,8?mm and 14?mm thickness were designed and accomplished. Force-crack open displacement (Force-COD) curves and mixed crack initial angles with various thicknesses under all loading conditions were obtained. It is showed that the thickness and load mixity have a strong influence on specimen strength and crack initial angle. The strength of thin plate is higher than that of thick plate under pure Ⅰ mode; the strength of 4 mm-thick plate is the highest, 2 mm close to 8 mm, 14 mm the smallest under Ⅰ+Ⅱ mode; and the strength of all kinds of thickness is almost the same under pure Ⅱ mode. The crack initiation direction in 2 mm-thick specimens is mostly the same as that in 14 mm-thick specimens under all sorts of mode mixity. However, it is a little higher in 4 mm-thick specimens and much lower in 8 mm-thick specimens. The maximum tangential stress criterion established on the basis of plane hypothesis is adequate to predict the direction of crack initiation of 2 mm and 14 mm plates under mixed mode load condition, however not suitable to 8 mm-thick plates.

关 键 词：LC4CS 复合型断裂 起裂角 载荷位移曲线 裂纹尖端张开位移 三维约束效应 断裂准则 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG111.91[金属学及工艺—金属材料]