Dynamic stability of multilayered beam with bolted joints

Abstract

Dynamic stability of elastic systems deals with the study of vibrations induced by pulsating load that are parametric with respect to certain form of deformations. An important aspect in the analysis of parametric dynamic system is the establishment of the regions in the parametric space in which the system in unstable, these regions are known as regions of dynamic instability. The boundary separating the stable zones from unstable zones is called stability boundaries and plot of these boundaries on the parametric space is called a stability diagram. Beams are the simplest structural members in any machine, mechanism or large structure. Layered structures are gaining importance in present day use because of their good vibration damping characteristics. The objective of the present work is to study the dynamic stability of a multilayered bolt jointed beam with fixed-fixed boundary condition and subjected to a pulsating end force. Finite element method is used for theoretical analysis. Experiments have been carried out to validate the theoretical findings. For this a test rig has been designed and fabricated to provide the required variable loading and necessary attachments have also been fabricated to simulate the fixed end conditions. The theoretical and experimental investigations show that the multilayered bolt jointed beam with fixed-fixed end condition is more stable than a single layered beam with similar end condition. The stability of the beam improves with increase in number of layers. The theoretical results matched very well with the experimental one.