多裂纹结构剩余强度的均匀设计研究

摘要

多部位损伤会造成工程结构剩余强度的大幅下降。为了更好地探索不同因素对工程结构剩余强度的影响能力，以均匀设计的实验设计和有限元分析方法，探索了连通距离、宽度和深度等三个因素对于结构剩余强度的影响，并用非线性拟合得到经验公式。研究结果表明：连通距离在10～20 mm范围内，剩余强度与连通距离成线性关系，在裂纹宽度10 mm、裂纹深度0．75 mm、连通距离从10 mm增大到20 mm时，剩余强度从352．8 MPa增加到388．6 MPa；剩余强度与裂纹宽度在5～10 mm的范围内成线性关系，在连通距离20 mm、裂纹深度0．75 mm、裂纹宽度从5 mm增加到10 mm的过程中，剩余强度从360．8 MPa增加到388．6 MPa；剩余强度与裂纹深度成四次多项式关系，裂纹深度从0．25 mm增加到0．75 mm的过程中，剩余强度的降幅大于40 MPa，其影响能力明显大于前两者。研究结果对于工程结构剩余强度的评估提供了有价值的参考。%Multi-site damage can make residual strength of structure reduced greatly .To explore the influence of connecting distance , crack width and depth on residual strength of structure , these three elements are researched using uniform design method and finite element analysis .Then the corresponding formula is fitted .The results indi-cate that the residual strength increases with connecting distance linearly at the range of research , rising from 352.8 MPa to 388.6 MPa with the connecting distance changing from 10 mm to 20 mm when crack width is 10 mm and depth is 0.75 mm.The residual strength increase with the increase of crack width linearly .When connecting dis-tance is 20 mm and crack depth is 0.75 mm, the residual strength is changing from 360.8 MPa to 388.6 MPa with crack width increasing from 5 mm to 10 mm.The residual strength changed with crack depth which is fitted quartic polynomial relation .When crack depth increasing from 0.25 mm to 0.75 mm the decreasing amplitude of residual strength is more than 40 MPa which is greater than the influence ability of crack distance and width .This research provides a valuable reference for evaluating the residual strength .