螺栓松动损伤的亚谐波共振识别方法
Using Sub-harmonic Resonance to Detect Bolted Joint Looseness

螺栓松动将导致结构完整性的破坏，螺栓连接状态的实时有效监测和评估具有重大意义。提出了一种基于亚谐波共振分析的螺栓松动识别方法。针对螺栓连接结构简化的单自由度非线性模型，采用多尺度方法分析了亚谐波共振现象，定性模拟了螺栓松动损伤亚谐波激励条件。以铝梁螺栓搭接结构为实验对象，利用粘贴在铝梁表面的压电作动/传感单元，采用不同频率的激励信号作用在作动片上，传感片接收响应信号，对其进行频谱分析，通过提取响应频谱中的亚谐波成分进行螺栓松动损伤识别。仿真与实验结果表明，亚谐波产生所需激励频率在两倍固有频率附近，使用亚谐波检测方法能有效识别螺栓松动。
Bolted-joint structures are prone to loosening under vibration, which affects the structural integrity. This paper presents a bolt looseness recognition method based on the sub-harmonic resonance analysis.The bolted-joint structure was simplified to a nonlinear single-degree-of-freedom (SDOF) model, and the multi-scale method was used to explain the sub-harmonic resonance. Experiments were performed on an aluminum beam with a loosened-bolted simulating the damage. Two surface-bonded piezoelectric transducers were used to generate continuous sinusoidal excitation and receive corresponding wave signals. The experimental results demonstrated that the sub-harmonic components appeared when subject to the excitation frequency twice of the natural value, which can be effective on bolt looseness damage detection.