This The bolted joint is the best choice for detachable assembly of components in structures and machines to maintain integrity in fastened structure due to their high reliability, strong load bearing capacity, easy maintenance and inspection at low cost. However, in many applications bolt connections are often subjected to low velocity impact loading during their service life which reduce the preload on bolted joint and leads to failure of engineering structures. Reduction in preload (Loosening) of bolted connections in a structure can significantly reduce its load bearing capacity. Detecting loosening of bolted connections at an early stage can prevent failure of the structure. Due to the complex geometry of a bolted connection, it is difficult to detect loosening of a bolted connection using conventional nondestructive test methods. A vibration-based method that uses changes in natural frequencies of a structure is effective in detecting loosening of bolted connections since the method focuses on detecting a stiffness reduction of bolted structure. The present work is focused on analyzing effect of preload on natural frequency of bolted joined structure subjected to low velocity impact loading. The effect of preload is carried out in experimental analysis and simulated by Pre- Stressed Modal Analysis.
Keywords— Preload, Low velocity impact, Natural frequency measurement, Bolted joint.