压力容器开孔间距对应力集中的影响

Influence of holding space at pressure vessel on the stress concentration

采用ANSYS有限元软件,对压力容器筒体上不同中心距L的两相邻直径为d的开孔周边应力场进行分析,并定义参数K=L(/2d)。结果表明:无接管模型开孔周边最大应力大于有接管模型,故基于无接管模型的分析结果相对安全;当K<0.9时,随着两开孔间距的增大,开孔中心线上的最小应力显著减小;当K=0.9～1.5时,开孔中心线上的最小应力随开孔间距的增大缓慢减小;当K>1.5时,开孔中心线上的最小应力均接近筒体远离开孔部位的应力。综合分析应力集中系数及应力集中影响范围,可知当K>1.7时,两开孔不存在干涉作用,可视为相互独立开孔。

With ANSYS finite element software,this paper analyzes the opened rim stress field with different center distances L at two adjacent holes with diameter d in a cylinder of pressure vessel,defined the parameter K as L/(2d).Analytic conclusion displays that the maximum opened rim stress value for nipple pipe free model is bigger than that of nipple pipe model,therefore,the value from the former is relatively safe.When K is more than 0.9,the minimum stress value along the center line of openings is decreased significantly with the increase of holing space.When K=0.9～1.5,the minimum stress is gradually decreased.When K is more than 1.5,the minimum stress value is close to the stress of the cylinder's location,far away from the openings.Comprehensive analysis make clear that for the concentration factor of stress and its impact range,when K is more than 1.7,there is no interference between two openings,which can be deemed as independent openings.