Observation of nonlinear dynamics of assembled structure of duralumin with bolted joints
Bolted joints are widely used in mechanical engineering. Due to the complex internal mechanics, joint can significantly affect the dynamics of the structure. Although the exact mechanics of the phenomena in the contact layer of the joint is completely unclear, there are works that give a phenomenological description of the dynamic properties of the joints of parts made of steels. However, there are few works devoted to the study of fixed joints made of light alloys. The article is devoted to the study of the nonlinear dynamics of composite samples made of duralumin. The study was made by investigation of free damped oscillations of the test rig. Dependences of damping and instantaneous frequency on the amplitude of vibrations were constructed based on the received signals of vibration accelerations by applying the Hilbert transform. The separation of the signal into separate modes was carried out using the analysis of the singular spectrum. The obtained dependences are similar in nature to the amplitude dependences for bolted joints of structural steel parts; however, the damping decrement is more than 2.5 times greater.