压力管道焊缝含环向表面裂纹J积分估算方法

J-Estimation Method of Pipe Welded Joints with Circumferential Surface Crack

关键词:  管道  焊缝非匹配  表面裂纹  J积分  有限元模型

Key words:  pipe  weld mis-match  surface crack  J-integral  finite element

摘要:

基于SC.ENG(表面裂纹工程估算)方法的基本原理,建立了弯矩作用下压力管道焊接接头含有内表面、等深度及有限长度环向表面裂纹的J积分近似估算公式,在计算公式中考虑了焊缝非匹配因素的影响。与SC.ENG1和SC.ENG2方法相对应,在此分别称所推导的J积分估算方法为SC.ENG3和SC.ENG4方法。该方法建立在塑性形变理论、Ramberg-osgood本构关系和等效原则基础上,通过使裂纹存在时的结构柔度与壁厚局部减薄时模拟结构的柔度相等的方式建立J积分的估算公式。有限元数值解验证了上述J积分估算公式的有效性。

Abstract:

Approximate J-estimation methods including the weld mis matching effects for a circumferentially surface cracked pipe with an internal,constant depth and finite length surface flaw under pure bending are developed.These are referred to SC.ENG3 and SC.ENG4 in corresponding to SC.ENG1 and SC.ENG2 methods.It is assumed that the Ramberg-Osgood power-law and the plasticity deformation theory control the stress strain response of the base and the weld material.The closed form J-solutions in terms of elementary functions are derived from the classical beam theory combined with an equivalence criterion.Several numerical examples of pipe welded joints are presented to verify the feasibility of the proposed methods.