Self-Loosening Characteristics of Three-Dimensional Printed Bolted Joints

Wi, Jun-Hee; Ahn, Hyoung-Jong; Lee, Kwang-Hee; Lee, Chulhee

doi:10.1089/3dp.2018.0017

Cited by 6 publications

(6 citation statements)

References 9 publications

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“…The standard test in the existing research was that the scholar Junker built a bolt loosening experimental device, as shown in Figure 1a. The bolt loosening test curve based on this is shown in Figure 1b [24]. P represents preload and θ represents the angle of nut rotation.…”

Section: Problem Descriptionmentioning

confidence: 99%

“…Jiang [23] used the thin-layer element method to identify the mechanical properties of the contact surface of the bolted structure, but cannot express the mechanical characteristics during loosening. Wi [24] has studied the self-loosening phenomenon of 3D printed bolts under transverse vibration through finite element analysis and experiments. Zhang [25] proposed a finite element model that considers the evolution of the wear profile of the thread surface to simulate self-loosening of the bolt under transverse load.…”

Section: Introductionmentioning

confidence: 99%

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Loosening of Bolted Connections under Transverse Loading in Timber Structures

Chen

Wang

et al. 2020

Forests

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Bolted joints are widely used in timber structures, and the loosening of bolt connections will reduce the structural performance. In this paper, a mechanical model of bolt connection for timber structures is established, and the process of bolt loosening under a transverse load is investigated. By using the finite element method to construct an accurate thread model with a helix angle, the thread contact state during the bolt loosening procedure was analyzed in detail, and the factors such as load amplitude, load frequency, load location, and different timber materials on bolt loosening are also studied. In the timber structure, the load amplitude is the main factor affecting the bolt loosening, the decay rate of the preload in the bolted joint is positively correlated with the amplitude of the cyclic transverse load. The frequency of the loading has a smaller effect on the looseness, the preload decreases as the frequency increases. When the load is applied to the smooth rod part of the bolt, the preload force will decrease rapidly, and the distance between the load position and the bolt has no effect on the change in looseness. The decreasing range of the preload is different with different timber material, but the decreasing law is the same. The model can be applied to analyze the loosening rule of bolted connections in timber structures.

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Section: Problem Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Loosening of Bolted Connections under Transverse Loading in Timber Structures

Chen

Wang

et al. 2020

Forests

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“…Additive manufacturing (AM) nowadays represents a reliable technology to fabricate metallic, polymeric, ceramic as well as composite components, driven by applications in automotive, aerospace, defense, healthcare, architecture and construction industries (“3D Printing Market Size, Share, Business Fotune Insights”, 2021; Spaggiari and Denti, 2019). Among the current mainstream AM technologies, material extrusion (MEX) process is mainly engaged in industries and offices due to its low material and machine cost, simple fabrication process, reliability and safety (Masood and Song, 2004; Wi et al , 2019). However, regardless of the advantages that MEX has to offer, there are distinct drawbacks that are obstructing its forward vertical integration into the manufacturing industry (Dugbenoo et al , 2018; Fieger et al , 2020; Yap et al , 2020).…”

Section: Introductionmentioning

confidence: 99%

Investigations on friction stir spot welding to overcome bed size limits of material extrusion (MEX) 3D printers

Tiwary,

Padmakumar,

Malik

2023

RPJ

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Purpose Material extrusion (MEX) 3D printers suffer from an intrinsic limitation of small size of the prints due to its restricted bed dimension. On the other hand, friction stir spot welding (FSSW) is gaining wide interest from automobile, airplane, off-road equipment manufacturers and even consumer electronics. This paper aims to explore the possibility of FSSW on Acrylonitrile Butadiene Styrene/Polylactic acid 3D-printed components to overcome the bed size limitation of MEX 3D printers. Design/methodology/approach Four different tool geometries (tapered cylindrical pin with/without concavity, pinless with/without concavity) were used to produce the joints. Three critical process parameters related to FSSW (tool rotational speed, plunge depth and dwell time) and two related to 3D printing (material combination and infill percentages) were investigated and optimized using the Taguchi L27 design of experiments. The influence of each welding parameter on the shear strength was evaluated by analysis of variance. Findings Results revealed that the infill percentage, a 3D printing parameter, had the maximum effect on the joint strength. The joints displayed pull nugget, cross nugget and substrate failure morphologies. The outcome resulted in the joint efficiency reaching up to 100.3%, better than that obtained by other competitive processes for 3D-printed thermoplastics. The results, when applied to weld a UAV wing, showed good strength and integrity. Further, grafting the joints with nylon micro-particles was also investigated, resulting in a detrimental effect on the strength. Originality/value To the best of the authors’ knowledge, this is the first study to demonstrate that the welding of dissimilar 3D-printed thermoplastics with/without microparticles is possible by FSSW, whilst the process parameters have a considerable consequence on the bond strength.

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“…Up until now, most research on the mechanics of bolted connection looseness refer to the equipment designed by Junker [ 28 ]; Figure 1 a. The testing results of the correlation between the bolt preload and rotation angle are given in Figure 1 b [ 29 ], where P represents the preload and θ is the rotation angle of the nut. When no relative sliding exists between the bolt and nut, the preload curve stays relatively gentle in stage I, and the looseness angle is miniscule.…”

Section: Introductionmentioning

confidence: 99%

Detection Method for Bolted Connection Looseness at Small Angles of Timber Structures based on Deep Learning

Liu

Chen

et al. 2021

Sensors

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Bolted connections are widely used in timber structures. Bolt looseness is one of the most important factors leading to structural failure. At present, most of the detection methods for bolt looseness do not achieve a good balance between cost and accuracy. In this paper, the detection method of small angle of bolt loosening in a timber structure is studied using deep learning and machine vision technology. Firstly, three schemes are designed, and the recognition targets are the nut’s own specification number, rectangular mark, and circular mark, respectively. The Single Shot MultiBox Detector (SSD) algorithm is adopted to train the image datasets. The scheme with the smallest identification angle error is the one identifying round objects, of which the identification angle error is 0.38°. Then, the identification accuracy was further improved, and the minimum recognition angle reached 1°. Finally, the looseness in a four-bolted connection and an eight-bolted connection are tested, confirming the feasibility of this method when applied on multi-bolted connection, and realizing a low operating costing and high accuracy.

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Self-Loosening Characteristics of Three-Dimensional Printed Bolted Joints

Cited by 6 publications

References 9 publications

Loosening of Bolted Connections under Transverse Loading in Timber Structures

Loosening of Bolted Connections under Transverse Loading in Timber Structures

Investigations on friction stir spot welding to overcome bed size limits of material extrusion (MEX) 3D printers

Detection Method for Bolted Connection Looseness at Small Angles of Timber Structures based on Deep Learning

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