Analysis of Additional Load and Fatigue Life of Preloaded Bolts in a Flange Joint Considering a Bolt Bending Load

Okorn, Ivan; Nagode, Marko; Klemenc, Jernej; Oman, Simon

doi:10.3390/met11030449

Cited by 11 publications

(3 citation statements)

References 30 publications

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“…As stated previously, there is no standardized method for testing bolt assemblies subjected to combined tension and bending [27]. For this reason, the effects of the modelling criteria the bolt material and for bolt-nut interaction are observed by using them in the case of a flush end plate bolted link and an extended end plate bolted link.…”

Section: Discussionmentioning

confidence: 99%

Simplified Modelling of Failure in High Strength Bolts under Combined Tension and Bending

2022

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Bolted connections are widely adopted in steel structures and their behaviour affects to a large extent the global response of the system. High-strength bolts of type HV are commonly employed. Under pure tension, these bolt assemblies usually fail by thread stripping. However, it was observed experimentally that, under combined tension and bending, the failure mode changes to fracture of the shank. The former loading condition commonly occurs in the case of thick extended end plate connections and the latter in the case of flush end plates. In order to analyse the behaviour of the structure, the finite element method (FEM) is usually employed. While there is a wealth of information on FEM modelling of bolts for standard loading conditions (e.g., tension), the authors are unaware of a model able to replicate both tension-only and combined tension and bending conditions. In this paper, a simplified approach to be used in the framework of FEM is proposed to model the behaviour of high-strength HV bolts which can replicate the failure mechanism of bolts under tension only and combined tension and bending. The bolt assembly is modelled with continuum elements, supplemented by a non-linear spring connecting the nut to the bolt shank. The spring captures the stiffness, resistance, and ductility of the bolt-to-nut threaded connection, reproducing the experimentally observed failure mode in the case of pure tension conditions. A simplified damage model is applied to the continuum finite elements used to model the bolt, which replicates shank failure under combined tension and bending as a result of large local stresses and strains occurring under these conditions. The proposed model captures with good accuracy the actual behaviour of high-strength HV bolts under tension only as well as under combined tension and bending.

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Section: Discussionmentioning

confidence: 99%

Simplified Modelling of Failure in High Strength Bolts under Combined Tension and Bending

2022

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“…The L-type flange is widely used to connect the tower segments in wind turbine towers [1][2][3]. However, during flange manufacturing, it is common to make a slope on the flange surface, which might have negative effects on the stress distribution of the bolts [2,4,5]. Therefore, it is necessary to investigate the influences of flange surface flatness on the structural behavior of L-type flange joints (LTFJs).…”

Section: Introductionmentioning

confidence: 99%

Structural Behavior of L-Type Flange Joint with Various Flange Flatness Conditions

Tran,

Park,

Lee

2023

Energies

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The L-type flange joint is widely used to attach steel tower segments to each other. However, tolerances on the flange surface flatness may occur during its fabrication, leading to a negative impact on the bolt stress distribution. This study evaluates the influences of the flange surface flatness on the behavior of L-type flange joints through numerical simulations. First, the finite element model of a 5 MW L-type flange joint is established, and its accuracy is verified based on comparison with an experimental test. Using the same loading conditions and material properties, the influences of geometrical imperfections (i.e., flange-sided gap, tower-sided gap) on the structural response are investigated. Furthermore, the impact of the flange gap opening length is reported. The results show that the flange-sided gap outperforms the tower-sided gap, resulting in reduced stress concentration in the bolt. In addition, the stresses in flange-sided gapping joints increase with an increase in the opening length.

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“…Some research focuses on the application of finite element modelling to the study of threaded joints. Okorn et al [30] provided analytical calculations according to Verein Deutscher Ingenieur (VDI) Recommendation 2230 and numerical analysis using the finite element method (FEM). To verify the FEM analysis, the forces in the bolts were measured under preload and under service load on a test bench.…”

Section: Introductionmentioning

confidence: 99%

Assessment of the Durability of Threaded Joints

et al. 2021

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The article deals with the determination of the resistance to cyclic loading of the threaded joints of pressure vessels and defective elements according to the failure mechanics criteria. Theoretical and experimental studies do not provide a sufficient basis for the existing calculation methods for the cyclic strength of the threaded joints of pressure vessels. The short crack kinetics in the threaded joints, a shakedown in one of the joint elements of pressure vessels, i.e., in the bolt or stud, has not been studied sufficiently. The calculation methods designed and improved within the study were based on theoretical and experimental investigations and were simplified for convenient application to engineering practice. The findings could be used to investigate the shakedown of studs of a different cross-section with an initiating and propagating crack. Value: the developed model for the assessment of durability of the threaded joints covers the patterns of resistance to cyclic failure (limit states: crack initiation, propagation, final failure) and shakedown (limit states: progressive shape change and plastic failure). Analysis-based solutions of plastic failure conditions and progressive shape change were accurate (the result was reached using a two-sided approach; the solutions were obtained in view of the parameters of the cyclic failure process in the stud (bolt) and based on experimental investigations of the threaded joints).

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Analysis of Additional Load and Fatigue Life of Preloaded Bolts in a Flange Joint Considering a Bolt Bending Load

Cited by 11 publications

References 30 publications

Simplified Modelling of Failure in High Strength Bolts under Combined Tension and Bending

Simplified Modelling of Failure in High Strength Bolts under Combined Tension and Bending

Structural Behavior of L-Type Flange Joint with Various Flange Flatness Conditions

Assessment of the Durability of Threaded Joints

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