铝合金板件环槽铆钉搭接连接受剪性能试验研究

Experimental study on shearing behavior of lockbolted lap connection for aluminum alloy plates

针对工程中常用的铝合金板件环槽铆钉搭接连接,进行了受剪性能的静力试验。通过拉伸试验测得铝板用6061-T6铝材和铆钉用304HC不锈钢材的物理参数,测定了环槽铆钉的预紧力。试验中获得了12个单铆钉搭接连接试件的荷载-位移曲线和极限荷载,分析了其破坏模式及铆钉孔径、端距、边距等参数的影响。结果表明:试件的破坏形式有环槽铆钉剪切破坏、板件顶端纵向撕裂破坏与侧边横向撕裂破坏3种,控制铆钉孔端、边距尺寸能避免后两种破坏;环槽铆钉预紧力在板件间产生的摩擦力有限,因此该搭接连接应属于承压型连接;铆钉与孔壁间的间隙最终会因板件间的相对滑移而致密,故过大的铆钉孔径将造成大的残余变形,但对承载力的影响有限;剪力作用下节点的荷载-位移曲线早期有较明显弹性段,可取其弹性段的末端荷载值作为受剪承载力设计值,极限荷载和该承载力设计值的比值约为2.3。

Static tests were carried out to study the shearing behavior of the lockbloted lap connections which are normally used for aluminum alloy plates. Mechanical parameters of the 6061-T6 aluminum and the 304HC stainless steel lockbolt were obtained by tensile tests. The pretension in lockbolt was also determined. The load-displacement curves as well as bearing capacities of 12 lap connections with single lockboh were further investigated by tensile tests. The failure modes were analyzed with emphasis on the influences of aperture, end distance and edge distance of bolt hole. The test results reveal that three failure modes exist for this kind of lap connection, including the shearing failure of lockboh, end fracture failure of plate and the side fracture failure of plate. The last two failure modes, however, can be avoided by controlling the end distance or edge distance of bolt hole. The pretension of lockbolt provides very limited friction force between plates, so this kind of lap connection actually works in a bearing manner. The gap between the lockboh and its hole wall finally leads to a relative sliding between two plates, thus oversized bolt hole will cause large residual deformation, even though its influence on the ultimate bearing capacity is limited. There is an obvious early elastic stage in the load-displacement curve of the connection under shear force. It indicates that the terminal value of elastic stage can be adopted as the design bearing capacity of the connection. In this case, the ratio of the bearing capacity to the design bearing capacity is about 2.3.