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

Nassar, Sayed A.; Housari, Basil A.

doi:10.1115/1.2717227

Cited by 37 publications

(27 citation statements)

References 7 publications

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“…Nassar and Housari [10][11][12][13][14][15] proposed a mathematical model based on the differential equation and experiment to study the bolt loosening caused by vibration. ey also studied the influence of the pitch, preload, hole clearance, friction, and transverse excitation on loosening.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study and Life Prediction of Bolt Loosening Life under Variable Amplitude Vibration

Yang

Che

Xiao

et al. 2019

Shock and Vibration

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The transverse vibration test of bolts has been designed with adoption of the fatigue tester to study the features of the loosening life of bolts. Firstly, the transverse vibration frequency has been changed, the effects of the amplitudes of displacement, velocity, and acceleration on the loosening life of bolts have been compared, and it has been confirmed that the transverse displacement amplitude is the main factor that affects bolt loosening in low-frequency vibration. Secondly, the loosening degree of the bolts preloaded standard under five displacement amplitude grades has been monitored and the bolt loosening situation has been expressed through the residual preload-vibration times curve. The data of each stage of residual preload under each displacement amplitude were summarized, and the displacement-life (D-N) curve of bolt loosening under different loosening situations (percentage of residual preload) which is referred to the material fatigue life S-N curve was drawn. Finally, the accumulation mechanism of bolt loosening has been studied and the linear accumulation model of bolt loosening has been set up through designing variable amplitude vibration tests at high-low and low-high displacement stages. Results show that, through the bolt loosening D-N curve, it can be found out that the bolt loosening life curve and the material fatigue life curve are with features of double line and high- and low-cycle boundary under the logarithmic coordinate. Linear accumulation of bolt loosening is with similar principle of linear damage accumulation of material fatigue. Therefore, the bolt loosening life can be predicted through bolt displacement-loosening life (D-N) curve attained from the experiment and the established linear accumulation model of bolt loosening.

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Section: Introductionmentioning

confidence: 99%

Experimental Study and Life Prediction of Bolt Loosening Life under Variable Amplitude Vibration

Yang

Che

Xiao

et al. 2019

Shock and Vibration

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show abstract

“…Additionally, Nassar and Housari [13,14] used a simplified mathematical model to investigate some factors on self-loosening of threaded fasteners such as the hole clearance, thread fit, thread pitch, and initial tension. In subsequent work, Nassar et al [15][16][17] proposed a more accurate mathematical model to predict the variation of the preload during the self-loosening process by investigating the relationship between the bearing friction torque, the thread friction torque, and the pitch torque components.…”

Section: Introductionmentioning

confidence: 99%

Self-Loosening Failure Analysis of Bolt Joints under Vibration considering the Tightening Process

Chen

Gao

Guan

2017

Shock and Vibration

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By considering the tightening process, a three-dimensional elastic finite element analysis is conducted to explore the mechanism of bolt self-loosening under transverse cyclic loading. According to the geometrical features of the thread, a hexahedral meshing is implemented by modifying the node coordinates based on cylinder meshes and an ABAQUS plug-in is made for parametric modeling. The accuracy of the finite element model is verified and validated by comparison with the analytical and experimental results on torque-tension relationship. And, then, the fastening states acquired by different means are compared. The results show that the tightening process cannot be replaced by a simplified method because its fastening state is different from the real process. With combining the tightening and self-loosening processes, this paper utilizes the relative rotation angles and velocities to investigate the slip states on contact surfaces instead of the Coulomb friction coefficient method, which is used in most previous researches. By contrast, this method can describe the slip states in greater detail. In addition, the simulation result reveals that there exists a creep slip phenomenon at contact surface, which causes the bolt self-loosening to occur even when some contact facets are stuck.

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“…Hence, the resistance of bolted joint against the vibration is lower (Figure 2 -23). This has been experimentally proven by Basil Housari [8]. His results show that with a larger hole clearance, less cycles are required to loosen a bolted joint.…”

Section: The Factors Influencing Self Loosening Of a Bolted Jointmentioning

confidence: 83%

“…Applying the Fourier Transform to Equation (3)(4)(5)(6)(7)(8)(9), the linear relation between the input and output of the system can be formed as follows:…”

Section: Transduction Matrix Of Brushed DC Motorsmentioning

confidence: 99%

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Tightening and loosening of bolted joint

Tanra¹

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A bolted joint is a common joint encountered in mechanical structures or machine design. Its tightness is important in order to secure the structure or machine it is attached to. A proper tightness is installed at a bolted joint to resist static and dynamic loading it is subjected to. When tightness is not sufficient, it can cause failure such as loosening and in extreme cases, joint separation. In this project, a bolted joint and its tightness are objects being studied. The purpose of this project is to understand the factors affecting tightness of a bolted joint and causes of its loosening under dynamic loading (vibration). A DC motor with known transduction matrix was used as a device to measure mechanical condition of a bolted joint. By obtaining the 2x2 transduction matrix, mechanical output of a DC motor can be related with its electrical input. With this relation, a DC motor was used to tighten a bolted joint and measure its mechanical condition by controlling and measuring its electrical input. Based on this mechanical condition, tightness and dynamic condition of a bolted joint were obtained. The project is divided into 2 parts. In the first part, the tightening process of a bolted joint is studied. The experiment results show that torque is not sufficient in indicating tightness of a bolted joint. Under different friction conditions, tightness that is achieved by the same value of torque differs significantly. Thus, energy is used as a tightening indicator. With simultaneously measurement of torque and rotation speed, energy applied to a bolted joint can be measured. The experiment results show that energy is a better tightening indicator as compared to torque. In the second part, dynamic behavior of a bolted joint under dynamic loading is studied. First, mechanical impedance of a bolted joint is measured with usage of Hilbert Transform. The Hilbert Transform helps to obtain mechanical impedance in time domain. With this, change of mechanical impedance over a period of time can be monitored. By obtaining mechanical impedance, system properties can be Abstract ii derived from their relation. The results show that system properties of a bolted joint are affected by tightness of a bolted joint (preload), its surface condition and frequency of applied excitation. After obtaining system properties of a bolted joint, response of a bolted joint to a vibration, especially transverse vibration, can be calculated. The results show that a transverse vibration given to a bolted joint can cause loosening due to thread geometry and system properties of a bolted joint. Acknowledgment iii ACKNOWLEDGMENT I would like to praise my thanks to the God for the completion of this thesis report. I also would also like to thank my supervisor, Professor Ling Shih Fu, for his ideas, guidance and support in this research. Even in his busiest schedule, he still spends his time in discussing this research. Secondly, I would like to thanks my fellow friends, Lian Kar Foong, Wong Yoke Rong, Felicia Rezanda, Hossein Mousavi and Peng Xi...

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

Cited by 37 publications

References 7 publications

Experimental Study and Life Prediction of Bolt Loosening Life under Variable Amplitude Vibration

Experimental Study and Life Prediction of Bolt Loosening Life under Variable Amplitude Vibration

Self-Loosening Failure Analysis of Bolt Joints under Vibration considering the Tightening Process

Tightening and loosening of bolted joint

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