自紧工艺对复合材料压力容器金属内衬断裂强度的影响

Effect of autofrettage technique upon fracture strength of metallic liners for composite overwrapped pressure vessels

基于压力容器自紧前后金属内衬的应力分析,利用子模型方法建立了含内衬表面圆裂纹的有限元模型,使用区域积分法计算了其在工作压力下裂纹前缘的J积分值,研究是否采用自紧工艺和不同自紧压力值情况下的裂纹尖端强度。结果表明:经过自紧工艺处理后裂纹前缘的J积分值将明显提高,且随自紧压力值的增大而增大;随着裂纹尺寸的增大,相应的J积分值也增大,并且沿裂纹前缘的J积分曲线变陡。由此说明自紧工艺压力值的提高和裂纹尺寸的增加均增大了内衬开裂的风险,因此复合材料缠绕压力容器自紧工艺压力值的确定需进行金属内衬的断裂分析。

The finite element model of composite overwrapped pressure vessel（COPV） including a circular surface crack in the liner was constructed with the sub-model technique.Based on the stress analysis of the metallic liner before and after autofrettage technology,the J-integrals along the crack front under operating pressure were calculated by the domain integral method.The objective was to investigate the crack tip strength under the following two cases： whether considerd the autofrettage or not and autofrettage with different pressures.Results show that the J-integrals increase significantly after autofrettage and improve slightly due to a superior autofrettage pressure;the deeper crack would lead the J-integrals to become larger and the curve to become sharper.It could be concluded that the larger the autofrettage pressure or crack size,the more likely the crack will open.Therefore it is necessary to analyze the fracture behavior of metallic liner when determining the autofrettage pressure.