内压直管对称循环弯曲棘轮效应实验研究  

EXPERIMENTAL STUDY ON THE RATCHETING OF PRESSURIZED STRAIGHT PIPES SUBJECTED TO REVERSED BENDING

作　　者：高炳军[1] 陈旭[1] 陈刚[1] 

机构地区：[1]天津大学化工学院,天津300072

出　　处：《机械强度》2005年第2期246-250,共5页Journal of Mechanical Strength

基　　金：国家自然科学基金资助项目(19872049);教育部高等学校优秀青年教师教学科研奖励计划资助。~~

摘　　要：利用多轴疲劳实验机及自行设计的准三点弯曲实验装置,对20钢直管在不同内压与不同循环弯曲载荷下进行棘轮应变测试。棘轮应变由应变计检测,直管径向变形由自行设计的径向位移引伸计检测。实验发现,内压直管在一定循环弯曲载荷作用下,将首先沿环向产生棘轮应变,随着载荷的增加,轴向也将产生棘轮应变,但较环向小。随着棘轮应变的产生,直管圆截面变为椭圆截面。无论是不同试件,还是同一试件的多载荷步实验,均发现相同内压下,循环弯曲载荷增大,棘轮应变速率增大;相同循环弯曲载荷下,内压增大,棘轮应变速率增大。多载荷步加载时,以往棘轮应变会降低应有的棘轮应变速率,尤其在较大的载荷下先发生棘轮应变后,这种影响十分明显。利用直管准三点弯曲实验装置,确定内压直管循环弯曲的棘轮边界。Taking advantage of the multi-axial fatigue test machine and a self-designed quasi-three-point-bending apparatus, ratcheting was experimentally studied for the pressurized straight pipes subjected to reversed bending. The ratcheting strains were measured by strain gauges, and the radial deformation of the pipe was measured by self-designed radial displacement extensometers. It is shown that ratcheting initiates firstly in hoop direction and that in axial direction follows with the increase of loading but less in magnitude. The circular cross section turns into ellipse as the ratcheting strain accumulates. Ratcheting strain rate grows with the increase of reversed bending load or internal pressure for both different specimen with different loading and same specimen with multi-step loading. In multi-step loading, ratcheting rate suffers from the ratcheting history, especially for that with ratcheting history at higher level loading. Ratcheting boundary is determined with the aid of the quasi-three-point-bending apparatus.

关 键 词：内压直管 弯曲 多轴棘轮效应 实验研究 

分 类 号：U173.1[交通运输工程] TH123.4[机械工程—机械设计及理论]