Improvement of performance of bolt–nut connections, Part II: Experimental investigation

Majzoobi, G.H.; Dabbagh, M Agh-Mohammad; Asgari, Pegah; Pipelzadeh, M K; Hardy, Stephen

doi:10.1177/0954406214525950

Cited by 3 publications

(4 citation statements)

References 23 publications

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“…However, finite element analysis demonstrates that the stress along the center axis of the bolt rapidly approaches a constant value at about one-quarter of the bolt diameter away from the bearing faces of the head and the nut. 18,19 Moreover, photoelasticity studies have shown that, at a distance of nearly of one-third of bolt diameter away from the bolt head, the nut, and the transition point, the stress approaches uniformity throughout the cross section. 20 Although for the measurement of clamping force using bolt elongation it is desirable that the FBG sensor be strategically placed in the region of uniform axial strain, it is not mandatory if proper FBG sensor calibration is performed.…”

Section: Theory Of Fbg Sensor Operationmentioning

confidence: 99%

Bolt tension monitoring with reusable fiber Bragg-grating sensors

Khomenko

Koricho

Haq

et al. 2015

The Journal of Strain Analysis for Engineering Design

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Bolted/mechanical fastening is one of the oldest and most widely used joining techniques. While it has many advantages such as ease of assembly and repair, it also has some important limitations. One such concern is bolt clamping load control and monitoring during and after joint assembly. Conventionally used torque wrenches can provide only an approximation of the clamping load and cannot be used for load monitoring. Clamping force transducers are bulky, expensive, and cannot usually be incorporated into the bolted joint for continuous load monitoring in the field. In this work, a novel implementation of a transducer device, called here for convenience the ''bolt tension monitor,'' is described and tested. It utilizes removable and reusable fiber Bragg-grating sensor(s) embedded in a bolt shaft for preload and retained clamping force measurements. While the inherent small size of the fiber Bragg-grating provides precise monitoring without significant effect on the intrinsic properties of the bolt, the embedding of an fiber Bragg-grating sensor with temporary adhesives allows quick assembly, disassembly, and reassembly of the sensor. Furthermore, these instrumented bolts can be used for structural health monitoring and defect detection in joints and structures. The technique shows great potential in simple adaptation to conventional manufacturing practices, precise clamping load measurement, and structural health monitoring of bolts and resulting joints.

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Section: Theory Of Fbg Sensor Operationmentioning

confidence: 99%

Bolt tension monitoring with reusable fiber Bragg-grating sensors

Khomenko

Koricho

Haq

et al. 2015

The Journal of Strain Analysis for Engineering Design

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“…16,17 Dragoni 18 studied the thread pitch effect on steel bolts fatigue strength. The fatigue limit slightly increases as the pitch decreases in small low-grade steel bolts.…”

Section: Introductionmentioning

confidence: 99%

“…Studies have performed numerical simulations and experiments on joint shape changes aiming at reducing the stress concentration in fillets and at increasing the joints performance. 16,17 Dragoni 18 studied the thread pitch effect on steel bolts fatigue strength. The fatigue limit slightly increases as the pitch decreases in small low-grade steel bolts.…”

Section: Introductionmentioning

confidence: 99%

Experimental evaluation of cyclic stresses on axially loaded bolted joints

Griza

Silva

Santos

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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The bolted joints fatigue behavior was analyzed by using torque as tightening method and steel and aluminum as members' material. The bolt used in the current study was the M6 class 8.8. The bolt preload value was calculated based on the bolts' elongation in each applied torque. The fatigue limit increases as the torque increases up to the torque limit to fracture the bolt. This behavior was seen in both members' material. Steel members support higher torque before bolt fracture. An analytical study also evaluated the relationship between the cyclic stress amplitude and the mean stress experienced by fatigue-tested bolts based on the available models for joint stiffness. The results were compared to the bolt fatigue diagram by Burguete and Patterson. The herein studied linear elastic theoretical models showed wide range in the correlation between stress amplitude and mean stress.

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“…The former concerns the bolts' preload planning considering elastic interaction, including bolts number, distribution, preload sequence, preload size, etc. 6,7 In contrast, the latter mainly pays close attention to material creep, such as the bolt stress relaxation. 8 Due to elastic interaction, the tightened bolt loses part of its load as a result of the tightening of another bolt, which lies inside the influence area.…”

Section: Introductionmentioning

confidence: 99%

Modeling and numerical analysis of multi-bolt elastic interaction with bolt stress relaxation

Liu

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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Multi-bolt joint distributed around the connecting members are generally adopted to meet the high-performance assembly requirements in aerospace, energy and power industries. However, the initial preload could be low due to non-optimized preload sequence and bolt stress relaxation, especially at elevated temperature. Thus, it is necessary to take elastic interaction and bolt stress relaxation into account before jointing. In this article, a general multi-bolt elastic interaction with bolt stress relaxation is modelled analytically. First, the multi-bolt joint is characterized by ‘spring-node’ model and elastic interaction stiffness. Second, the bolt residual preload can be estimated according to linear superposition of elastic interaction and bolt stress relaxation under the condition of node displacement equilibrium. Further, the influence of preloading sequence and bolt stress relaxation on residual preload distribution was numerically analyzed using a typical circular ring with 8-bolt joint. Two bolts’ preloading sequences were planned, star sequence and counterclockwise sequence, respectively. The bolt creep simulation time was set as 10 h using the power-model at intermediate temperature. From comparison, the predicted results using the developed model were consistent with the FE simulations both with and without bolt stress relaxation.

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Improvement of performance of bolt–nut connections, Part II: Experimental investigation

Cited by 3 publications

References 23 publications

Bolt tension monitoring with reusable fiber Bragg-grating sensors

Bolt tension monitoring with reusable fiber Bragg-grating sensors

Experimental evaluation of cyclic stresses on axially loaded bolted joints

Modeling and numerical analysis of multi-bolt elastic interaction with bolt stress relaxation

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