Torque it up: a low-cost approximate method to prevent lateral load slip in mechanical hardware fasteners by determination of preload

Daniel R. Dell'Anno; Daniel P. DeSantis; John W. Pepi; Danielle M. Robare

doi:10.1117/12.2598670

11 August 2021 Torque it up: a low-cost approximate method to prevent lateral load slip in mechanical hardware fasteners by determination of preload

Daniel R. Dell'Anno, Daniel P. DeSantis, John W. Pepi, Danielle M. Robare

Author Affiliations +

Proceedings Volume 11816, Optomechanics and Optical Alignment; 118160D (2021) https://doi.org/10.1117/12.2598670
Event: SPIE Optical Engineering + Applications, 2021, San Diego, California, United States

Abstract

Determining preload for mechanical fastener hardware such as screws and bolts is critical to a successful aerospace mission. Preload helps to ensure that fatigue failure during operation is minimized, prevents gapping under applied dynamic loading while minimizing change in preload, and can prevent friction slip under high lateral loads. Many codes have been developed to approximate hardware torque to preload relationship dependent on friction, and high uncertainty factors are indicated (up to 35%) to bound analyses. More precise measurement of preload requires costly technique using strain gage or micro precision instrumentation. An approximate but low-cost method of determining preload for a given application is presented to prevent underloading of components, using standard hardware analytical techniques and breadboard testing. Results are shown accurate to better than the uncertainties, which can assist in determining proper torque requirement. Included are both lubricated and non-lubricated hardware, and effects of washers on preload.

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Citation Download Citation

Daniel R. Dell'Anno, Daniel P. DeSantis, John W. Pepi, and Danielle M. Robare "Torque it up: a low-cost approximate method to prevent lateral load slip in mechanical hardware fasteners by determination of preload", Proc. SPIE 11816, Optomechanics and Optical Alignment, 118160D (11 August 2021); https://doi.org/10.1117/12.2598670

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