基于螺栓头部端面应变状态的螺栓松动检测研究

Bolt Looseness Detection Based on Strain State of Bolt Head Surface

针对螺栓联接结构中的松动问题,提出了一种通过测量螺栓头部径向应变进而确定螺栓预紧力的方法。采用有限单元法分析了受不同预紧力作用下螺栓头部端面的应变状态,发现端面径向应变与所受预紧力之间存在较好的线性关系;并进一步对不同工况下的预紧力检测效果进行分析,发现螺栓在受到四种不同因素的影响下两者仍具有很好的线性关系。因此,可通过检测螺栓头部端面的径向应变,实现螺栓联接状态(表现为预紧力大小)的检测。设计了径向应变片,并制作了集成应变片的螺栓传感器,进行了实验研究。实验结果表明,螺栓头部端面径向应变与预紧力变化的线性关系明显,与有限元分析结果一致,说明所提出的方法和所设计的传感器能有效检测螺栓预紧力大小,进而实现对螺栓联接状态的检测,可作为螺栓联接结构健康检测的一种新途径。

A new bolt looseness(shown as the pre-tightening force)detection method through measuring the radial strain on the circumferential ring of the bolt head end surface is proposed.The bolt head surface strain states under different bolt preload are analyzed using the finite element method(FEM).The FEM results show that the radial strain of the bolt head end surface and the pre-tightening force has a good linear relationship.The bolt under different working conditions are analyzed,and the aforementioned linear relationship remains well even when the bolt is under the influence of four different factors.A bolt sensor with radial strain gages integrated on the bolt head surface are designed and fabricated.The experiments of bolt looseness detection based on the proposed method are performed for the designed bolt sensor.The experimental results show a good linear relationship between the output radial strain of the bolt head surface and the pre-tightening force,and this is consistent with the results of FEM analysis.The proposed method and the designed sensor can effectively detect the bolt pre-tightening force change and monitor the bolt connection state.The proposed method has profound application prospects.