A Controlled Tap Detection Method for Bolt Tightness
螺栓松紧程度的受控敲击检测方法

Bolt connection is an assembly form extensively used in engineering. Vibration or other ambient conditions may lead to bolt loosing, therefore the normal structure function may be deteriorated and even lead to severe security accidents. So, non-destructive testing method for bolt tightness has been concerned by researchers. In this paper, the sensitive part of power spectrum density of a bolt tapping device was adopted to detect the bolt loosing state. Since the tapping force is strictly controlled to ensure stimulation repeatability, the bolt loosing state can be quantitatively determined by using support vector machine method. Thus, a simple and effective detection method was developed without using complex nonlinear dynamic analysis. Experimental results demonstrate that good quantitative detection of bolt loosing state is possible by using the proposed method. Especially, when bolt is completely loosened or is at the beginning stage of loosing, a higher detection accuracy can be obtained.