A Procedure for Calculation of Torque Specifications for Bolted Joints with Prevailing Torque

Dean, SW; Reiff, JD

doi:10.1520/jai12879

Cited by 5 publications

(1 citation statement)

References 1 publication

(2 reference statements)

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“…13 The design charts for bolts preloaded up to the plastic range were characterized to describe the torque-preload relations 14 and the procedure for calculation of prevailing torque in bolted joints was developed analytically. 15 The influence of different preload levels on fatigue behavior and damage evolution of the metallic bolted joints were assessed via numerical modeling based on a combined continuum damage mechanics (CDM) theory and the critical plane approach. 16,17 But it’s not the case for composite joints where clamped composite components have poor properties in through-thickness direction and are susceptible to damage and failure.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of bolt pretightening and preload relaxation in composite interference-fit joints under thermal effects

Zhang

Cheng

et al. 2020

Journal of Composite Materials

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The present research investigates the mechanism of bolt pretightening and preload relaxation in composite interference-fit joint structures under thermal effects. In view of the dissimilar material properties and the interfacial friction in such joints, the mechanical behavior of bolt and composites during assembly can be regarded as immediate preload response which is described by a linear elastic model, whereas the long-term behavior of composites during preload relaxation in service is considered as delayed response which is characterized by a viscoelastic model. The clamping forces on both sides of joints were captured to evaluate the preload balanced by the frictional behavior. The preload relaxation of joints with various interference-fit sizes and tightening torques under thermal effects were monitored for 240 hours to calibrate and validate the proposed model. The research revealed that the interference-fit size determined the level of frictional force which resulted in a difference between clamping forces at two sides of the fasteners. The preload first increases slowly with the growth of temperature, then decreases sharply when it approaches to glass transition temperature of matrix. The interference-fit joint behaves better in terms of maintaining the stability of preload than clearance-fit joints.

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Section: Introductionmentioning

confidence: 99%

Mechanism of bolt pretightening and preload relaxation in composite interference-fit joints under thermal effects

Zhang

Cheng

et al. 2020

Journal of Composite Materials

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Optimal Space Filling Design Based Finite Element Analysis of Hydraulic Cylinder

Agarwal

Seretse

Pitso

2022

Lecture Notes in Mechanical Engineering

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Understanding the behaviour of silver as a low friction coating in aerospace fasteners

Tronci

Marshall

2016

Tribology International

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Nuts and bolts used in aero-engines are manufactured from heat-resistant super-alloys. When used in a like on like couple, these materials have a high coefficient of friction, and frequently seizure occurs. In order to prevent this, a silver coating is applied to the nut threads, providing a low friction boundary at the interface. Additionally, a radial crimp is applied to the nut, in order to provide a self-locking feature preventing vibration self-loosening. In this study, the coefficient of friction of the thread contact will be investigated both during initial joint assembly, and after thermal ageing. Additionally, a finite element model will be employed to investigate the contact mechanics as a consequence of the crimp. The low coefficient of friction observed during initial assembly was found to be a consequence of shear flow of the silver coating, with an approximate doubling of this value once the coating aged. Areas of silver removal were found to be coincident with areas of high contact pressure in the joint, attributable to the crimp feature.

show abstract

A Procedure for Calculation of Torque Specifications for Bolted Joints with Prevailing Torque

Cited by 5 publications

References 1 publication

Mechanism of bolt pretightening and preload relaxation in composite interference-fit joints under thermal effects

Mechanism of bolt pretightening and preload relaxation in composite interference-fit joints under thermal effects

Optimal Space Filling Design Based Finite Element Analysis of Hydraulic Cylinder

Understanding the behaviour of silver as a low friction coating in aerospace fasteners

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