摘要
双层管内压弯曲方法为获得大直径超薄弯管提供了可行的途径,文章对该方法避免内层管起皱的机理进行研究。内压在双层管轴向产生的附加拉应力,可降低弯曲内侧轴向压应力,有助于预防起皱。采用弹性理论,得到双层直管状态下附加轴向拉应力表达式,并对理论模型进行验证。通过数值模拟,分析了弯曲过程中支撑内压、外层管厚度,对内层超薄管起皱和轴向应力的影响规律。理论分析结果表明,双层管极限支撑内压,会随外层壁厚的增加而显著提高,因此对于厚度比较大的双层管,可以通过采用较大的支撑内压,提高附加轴向拉应力的方法避免起皱。模拟结果表明,随着外层管厚度增加,外层管弯曲时不易发生失稳起皱,同时弯管内侧轴向压应力绝对值降低。支撑内压越高,内外层界面贴合越紧密,内层管在承受轴向压应力时,其稳定性越高。
The double-layered tube hydro-bending process provides the possibility to get ultra thin products for liquid transportation systems.The mechanism of stabilizing of inner tube was studied by theoretical analysis and FE method.The internal pressure produce additional axial tensile stress to the double-layered tubes,which could decrease axial compressive stress at the inside arc and help to prevent wrinkling.The expression of the axial additional stress for the double layers straight tube was obtained by elastic theory,and the theoretical model was verified.The influences of thickness ratio and internal pressure on wrinkling and axial stress distribution during the bending process were investigated by numerical simulation.It is shown from the theoretical results that the limit internal pressure increases with the increase of thickness,which could increase the additional axial stress greatly and prevent wrinkling.The FE results show that with the increase of thickness of outer tube,the stability of the outer tube enhances and the internal axial compressive stress decreases.The higher the internal pressure,the more firm bond would be formed,and more stable would be the inner tube subjected to the axial compressive stress.
出处
《塑性工程学报》
CAS
CSCD
北大核心
2012年第3期48-53,共6页
Journal of Plasticity Engineering
基金
国家自然科学基金资助项目(51175111)
关键词
弯曲
双层管
起皱
轴向应力
bending
double-layered tube
wrinkling
axial stress
作者简介
胡蓝，男，1984年生，山东人，哈尔滨工业大学，博士研究生，从事液力成形技术研究
苑世剑E-mail：syuan@hit．edu．cn
