An analytical investigation of the collapse of asymmetrically corroded pipes under external pressure

This paper presents an analytical investigation of elastic collapse of asymmetrically corroded rings under external pressure when both internal corrosion and external corrosion exist.Governing equations are derived for membrane inextensible and membrane extensible cases;a full continuity condition is rigorously derived by the Euler-Bernoulli beam assumption.Comparison with finite element analysis(FEA)shows good agreement for load-displacement curves but membrane extensibility should be included to accurately predict the initial deformation phase,although the discrepancy for both the inextensible and extensible models vanishes for larger deformation phases.By the perturbation technique,the initial load-displacement slope is calculated,and extensive parametric analysis shows complicated dependency of this slope on the misalignment parameter and the angular extent of corrosion.We also present an infallible semi-analytical perturbation solution for both homogeneous and inhomogeneous cases by the Lyapunov arbitrary small-parameter method and show that the resulting power series always converges;then a mathematical argument of analyticity has been presented to illustrate that the so-called homotopy analysis method in the literature converges when the convergence controlling parameter is lying in(-2,0).This paper serves to enhance the understanding of asymmetrically corroded rings and it is mainly relevant to offshore engineering.

浙江大学特种控制阀研究室（英文）

目的:目前大中型控制阀大多存在结构复杂、驱动能耗大、反应时间慢、振动噪声大、稳定性差和使用寿命短等缺点。基于此,浙江大学相关研究人员组建了特种控制阀研究室,致力于提升控制阀的整体性能和设计水平。研究点:本研究室的主要方向为:1.控制阀内部流动特性分析和新结构设计开发;2.流体目标流量、温度、压力和振动噪声等的智能控制研究;3.适应纳米流体、压缩氢气和高温高压过热蒸汽等新流体介质的智慧控制阀研究。展望:特种控制阀作为超超临界火电机组、核电、石化高压反应和百万吨级乙烯工程等国家重大重点工程的关键零部件之一,将会在内流动机理、新结构开发、新流体介质和智能控制等研究领域得到广泛关注和长足发展。