Mechanical Systems: Bolted Joint Analysis and Preload Effects

This lecture covers the analysis of bolted joints, focusing on the behavior of these joints under external loads and the importance of preload. The instructor begins by summarizing previous concepts related to the relationship between torque and tensile force in bolts. The lecture explains how bolted assemblies behave like a series of springs, emphasizing the significance of preload in maintaining joint integrity. Various models are introduced to illustrate the rheological behavior of bolted connections, including the effects of external axial forces. The discussion extends to the limits of bolt usage, including the conditions for initial tightening and the impact of friction on preload. The instructor also addresses the consequences of thermal expansion and the phenomenon of settling in bolted joints. Practical applications, such as hydraulic tensioning methods, are explored to demonstrate their advantages in achieving accurate preload without introducing torsional stress. The lecture concludes with exercises to apply these concepts in real-world scenarios, reinforcing the theoretical knowledge presented.