Study of the Effect of Hole Clearance and Thread Fit on the Self-Loosening of Threaded Fasteners

This study provides an experimental and theoretical investigation of the effect of hole clearance and thread fit on the self-loosening of tightened threaded fasteners that are subjected to a cyclic transverse service load. An experimental procedure and test setup are developed in order to collect real-time data on the rate of clamp load loss per cycle as well as the loosening rotation of the bolt head. Three levels of hole clearance are investigated; namely, 3%, 6%, and 10% of the bolt nominal diameter. For the commonly used 2A thread fit for a selected bolt size, three classes of the nut thread fit are considered; namely, 1B, 2B, and 3B. A simplified mathematical model is used for the analytical investigation of the effect of the hole clearance and thread fit on threaded fasteners self-loosening. The experimental and theoretical results are presented and discussed.

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Study of the Effect of Hole Clearance and Thread Fit on the Self-Loosening of Threaded Fasteners

Design Engineering and Computers and Information in Engineering, Parts A and B ◽

10.1115/imece2006-15977 ◽

2006 ◽

Cited By ~ 2

Author(s):

Sayed A. Nassar ◽

Basil A. Housari

Keyword(s):

Analytical Investigation ◽

The Self ◽

Time Data ◽

Test Set ◽

Experimental Procedure ◽

Threaded Fasteners ◽

Service Load ◽

Set Up ◽

Theoretical Results ◽

Simplified Mathematical Model

This study provides an experimental and theoretical investigation of the effect of hole clearance and thread fit on the self-loosening of tightened threaded fasteners that are subjected to a cyclic transverse service load. An experimental procedure and test set up are developed in order to collect real-time data on the rate of clamp load loss per cycle as well as the loosening rotation of the bolt head. Three levels of hole clearance are investigated; namely, 3%, 6%, and 10% of the bolt nominal diameter. For the commonly used 2A thread fit for a selected bolt size, three classes of the nut thread fit are considered; namely, 1B, 2B, and 3B. A simplified mathematical model is used for the analytical investigation of the effect of the hole clearance and thread fit on threaded fasteners self-loosening. The experimental and theoretical results are presented and discussed.

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Effect of Thread and Bearing Friction Coefficients on the Vibration-Induced Loosening of Threaded Fasteners

Journal of Vibration and Acoustics ◽

10.1115/1.2748473 ◽

2007 ◽

Vol 129 (4) ◽

pp. 484-494 ◽

Cited By ~ 19

Author(s):

Basil A. Housari ◽

Sayed A. Nassar

Keyword(s):

Mathematical Model ◽

The Self ◽

Time Data ◽

Friction Coefficients ◽

Rotational Angle ◽

Transverse Loads ◽

Threaded Fasteners ◽

Solid Film ◽

Loosening Rate ◽

Bearing Friction

This study provides a theoretical and experimental investigation of the effect of the thread and bearing friction coefficients on the self-loosening of threaded fasteners that are subjected to cyclic transverse loads. The friction coefficients are varied by using different types of coating and lubrication. A phosphate and oil coating and an olefin and molydisulfide solid film lubricant are used on the bolts tested. A mathematical model is developed to evaluate the self-loosening behavior in threaded fasteners when subjected to cyclic transverse loads. An experimental procedure and test setup are proposed in order to collect real-time data on the loosening rate (rate of clamp load loss per cycle) as well as the rotational angle of the bolt head during its gradual loosening. The experimental values of the friction coefficients are used in the mathematical model to monitor their effect on the theoretical results for the loosening rate. Experimentally, the friction coefficients are modified by changing the coating or the lubrication applied to the fasteners. The theoretical and experimental results are presented and discussed.

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Mathematical methodologies for calculating the mass diffusion coefficient of bananas during drying

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/s1415-43662007000600011 ◽

2007 ◽

Vol 11 (6) ◽

pp. 623-627 ◽

Cited By ~ 8

Author(s):

Mariângela Amendola ◽

Marlene R. Queiroz

Keyword(s):

Differential Equation ◽

Diffusion Coefficient ◽

Mass Diffusion ◽

Drying Process ◽

Experimental Procedure ◽

Residual Values ◽

The Finite Difference Method ◽

Theoretical Results ◽

Minimal Residual ◽

Simplified Mathematical Model

In this work two mathematical methodologies to solve the diffusion differential equation related to the banana drying process were used in order to obtain the mass diffusion coefficient value. A simplified mathematical model was considered that was based on Fick's Law, with initial and boundary conditions according to the experimental procedure carried out for banana drying. The first methodology was performed by using an approximation of the analytical solution and the second by using the numerical simulation according to the implicit scheme of the finite difference method. The calculation was carried out by looking for the minimal value of the norm calculated between the experimental data and the theoretical results obtained using different values of the diffusion coefficient. The algorithms associated with these methodologies were implemented with Matlab. The values of the diffusion coefficient according to the first and second methodologies were 1.65 x 10-6 [m² h-1] and 1.58 x 10-6 [m² h-1] respectively, with the associated minimal residual values of 0.0269 and 0.0257.

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Effect of Coating and Lubrication on the Vibration-Induced Loosening of Threaded Fasteners

Design Engineering and Computers and Information in Engineering, Parts A and B ◽

10.1115/imece2006-16185 ◽

2006 ◽

Author(s):

Basil A. Housari ◽

Sayed A. Nassar

Keyword(s):

Mathematical Model ◽

The Self ◽

Time Data ◽

Rotational Angle ◽

Transverse Loads ◽

Threaded Fasteners ◽

Solid Film ◽

Set Up ◽

The Mathematical Model ◽

Loosening Rate

This study provides an experimental and theoretical investigation of the effect of the bearing friction coefficient and the thread friction on the self-loosening of threaded fasteners that are subjected to cyclic transverse service loads. Coating and lubrication affect the thread and the underhead friction of the fastener, which affects the loosening rate when it is subjected to transverse loads. A mathematical model was developed to evaluate the self-loosening behavior in threaded fasteners when subjected to cyclic transverse loads. An experimental procedure and test set up are designed in order to collect real-time data on the rate of preload loss per cycle as well as the rotational angle of the bolt head during its gradual loosening. The values of the coefficients of friction under the bolt head and between the threads were changed in the mathematical model to monitor their effect on the loosening rate. Experimentally, the friction coefficients are modified by changing the coating or the lubrication applied to the fasteners. One coating and one solid film lubricant are used, namely, phosphate and oil coating and Olefin and Molydisulfide lubricated bolts. The theoretical and experimental results are presented and discussed.

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