Mechanical Systems: Bolt Assembly Analysis

This lecture focuses on the analysis of bolted assemblies, particularly the forces and deformations experienced during initial preload and external axial loads. The instructor begins by summarizing previous concepts related to metric threads and their definitions. The discussion progresses to the mechanics of tightening and loosening bolts, emphasizing the relationship between torque and tensile force. The effects of friction at the thread and contact surfaces are examined, highlighting their impact on the overall performance of the assembly. The lecture introduces a rheological model to represent the behavior of the bolt and the assembled pieces under load, detailing how to calculate equivalent stiffness. The instructor illustrates the deformation of the bolt and the assembly when subjected to preload and external forces, explaining the significance of the load distribution. Finally, practical exercises are presented to apply these concepts, including calculations for determining the axial force required to achieve separation in a bolted assembly, reinforcing the theoretical principles discussed throughout the lecture.