Clamp Load Loss due to Elastic Interaction and Gasket Creep Relaxation in Bolted Joints

Nassar, Sayed A.; Alkelani, Ali A.

doi:10.1115/1.2218343

Cited by 57 publications

(17 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A detailed survey of problems of estimating the performance of structural members by analyzing stress relaxation can be found in [2]. An example of influence of relaxation processes in elastomers on pipeline component performance is given in [3], where the influence of properties of sealing gaskets made of various materials on the tightening force of flange connection bolts is studied experimentally. It is shown that in connections with styrene-butadiene rubber gaskets the tightening force for the considered connection can decrease by 50% and more in five minutes.…”

Section: Introductionmentioning

confidence: 99%

Study of viscoelastic properties of elastomers reinforced by nanoparticles

Zezin

Ломакин

2015

Mech. Solids

View full text Add to dashboard Cite

The results of experimental studies of hyperelastic and relaxation properties of polymer composites with elastomer matrix based on hydrogenated nitrile-butadiene rubber filled with technical carbon particles in the temperature range 20-125 • C are presented. The characteristic experimental strain curves of materials in extension at a constant strain rate and the stress relaxation curves in materials at various tensile strain levels are given. A possible version of constitutive relations for describing some specific features of mechanical behavior of the considered materials under finite strains is considered. The obtained experimental data are used to verify the proposed constitutive relations experimentally. It is shown that the temperature-time analogy permits one to use the obtained constitutive relations to analyze nonmonotone variations in the relaxation properties of the considered materials as the temperature increases in the range under study.

show abstract

Section: Introductionmentioning

confidence: 99%

Study of viscoelastic properties of elastomers reinforced by nanoparticles

Zezin

Ломакин

2015

Mech. Solids

View full text Add to dashboard Cite

show abstract

“…Polymeric gaskets, however, demonstrate viscoelastic behavior and thus are limited in life due to creep relaxation. Nassar and Alkelani [5] created an experiment to measure the relationship between the thickness of the gasket and gasket deflection. Even though gasket relaxation is affected by gasket thickness, t G , a thicker gasket does not necessarily translate to increased relaxation.…”

Section: Mechanics Of Flanges and Re-torquementioning

confidence: 99%

“…Care was taken in the current study to ensure that the assembly and tightening procedures were not only consistent from experiment to experiment, but also done in accordance with standard practices associated with gasketed flange assemblies. Several tightening strategies have been studied by Nassar and Alkelani [5] (i.e., star, clockwise, and simultaneous). For the current study, bolts were initially hand-tightened.…”

Section: Experimental Approachmentioning

confidence: 99%

See 1 more Smart Citation

Optimization of Re-Torque and Relaxation Parameters of the GUCP

Gordon

Drilling

Williams

et al. 2011

Volume 2: Computer Technology and Bolted Joints

View full text Add to dashboard Cite

Self-loosening of bolts in non-permanent connections has been the subject of a myriad of investigations; however, because the vast majority of these studies focused on applications with long-term service conditions involving creep and/or cyclic (working or vibratory) loading, there are no analytical techniques that have been developed to address the load decay behavior of bolted assemblies with gaskets under a primary followed up by a secondary torque. The Ground Umbilical Carrier Plate (GUCP) includes a gasketed ASME-type flange assembly that transfers pressurized, cryogenic hydrogen from the Space Transportation System (STS). Although the threaded stud material is nominally elastic under service conditions, the gasket material, a polytetrafluorethylene (PTFE) matrix filled with 25% chopped glass fibers, undergoes viscous, strain hardening deformation. The consequence of over-torquing the assembly is yielding the stud. Alternatively, the consequence of under-torquing is premature loosening and subsequent fuel leakage. As such, identifying the interactions between assembly configuration, initial torque, etc. to relaxation behavior of the assembly has been identified as a means to reduce the dwell period (the time between initial torque and re-torque). Research is carried out to identify the optimal torque parameters that confer a minimal dwell period. This article documents the Gasket Relaxation and Re-Torque Optimization (GRRO) program used to modify procedures employed when connecting the flanges to the fuel tank of the Space Transportation System prior to a launch.

show abstract

“…Due to the preferred orientation and the cellular structure, the sheet is resilient in the direction perpendicular to the sheet. This resiliency contributes to the ability of flexible graphite to serve as a gasket, such as a gasket for sealing fluids [8,10]. Because graphite is chemically and thermally resistant, the gasket is particularly valuable for functioning under harsh environments.…”

Section: Introductionmentioning

confidence: 99%