Sensitivity Analysis of Self-Loosening Behavior forMesoscale Bolt Assemblies Under Cyclic Lateral Loading

Abstract

This study aims to enhance the understanding of self-loosening in mesoscale bolt assemblies, specifically those with characteristic dimensions ranging from 100 to 3,000 micrometers. These bolts pose unique design challenges due to the small difference between their nominal dimensions and manufacturing tolerances. This work discusses the design of new instrumentation to test multimesoscale bolt assemblies under various loading conditions, an area previously focused only on larger bolts. A case study was conducted in collaboration with a mesoscale multi-bolt system that was experiencing self-loosening failures. This system was tested to determine its susceptibility to the self-loosening failure mode. An experimental study was conducted to identify the sensitivities of the system to geometric and loading environment parameters. A set of hypotheses were proposed as a way to facilitate new learnings about the system’s sensitivities to four different parameters. The findings from the experimental study provide valuable insights into how different geometric configurations and types of loading conditions contribute to the performance of mesoscale multi-bolted systems. Through these investigative efforts, the study successfully identified the existence of a critical displacement threshold for self-loosening in mesoscale multi-bolted systems that is sensitive to factors such as clamp length, amplitude of input displacement load, and screw position.