Authors: Zong De Liu, Xue Ping Mao
Abstract: The creep experiments of 2Cr11NiMoVNbNB steel were carried out at 550oC and 600oC. The creep damage laws of this material are discussed. An increase of the stress exponent with decreasing temperature was found experimentally and a modified secondary creep rate equation including in creep threshold stress was derived. Creep damage analyses are made under constant stress and under relaxed stress with creep threshold stress. The experimental results show that the
damage value calculated with creep time is almost equal to that calculated with the creep rate, and an iteration method of calculating is proposed.
1031
Authors: Yang Xiao, Masahiro Kuhara, Naoaki Noda, Kinjiro Saito, Masato Nagawa, Atsushi Yumoto, Ayako Ogasawara
Abstract: The bolts and nuts are widely used in various fields as important joining elements with
long history. However, loosening induced by the vibration and external loads is still a big problem.
And the loosening sometimes causes very serious accident without notice. This paper deals with a
special stud bolt named “Super Stud Bolt (SSB)” which can prevent loosening effectively. There is
a thin walled tube between the upper and lower threads, which can be deformed along the axial
direction so that the phase difference is produced and SSB is developed. This phase difference
induces the contrary force on the surfaces of the upper and lower threads, which brings out the
anti-loosening performance. In this study, the processing and fastening-loosening courses are
simulated with the finite element method. And the anti-loosening performance is analyzed and
realized. In addition, the anti-loosening performances under various phase differences are compared
and finally best dimensions for SSB are examined.
249
Authors: Ji Xiang Luo, Chun Tang
Abstract: The riveting is widely used for fitting together two or more elements of structure in the same or different materials. In these assemblies the stress field is complex, we have to consider the effect of the geometrical discontinuity, the contact, the tightening, the material properties and the applied load. The current work focus on the study of fretting fatigue crack formation in common 6XXX aluminum alloys, used in land transportation equipments, and uncovering characteristic origins of crack by experimental and numerical methods based on multi-axial fatigue life models. 3D finite element models were validated by the experimental results obtained with strain gauges. The influences of the contact friction coefficient at the fretting surface, the fastening forces and the remote stress applied in the fretting fatigue experiments on the crack origins are discussed by the comparison of the different numerical results.
1388
Authors: Yue Xu, Jun Wen Qiu
Abstract: This paper using the method of combining balance static calibration with finite element analysis research the change and distribution law, and analyze the influence of the law on primary coefficient of hinge moment balance measurement, in conditions of different fixed-end geometry size and different preloaded force of fastening bolt.
833
Authors: Eduardo Luis Gaertner, José Divo Bressan, Anne Karollyne Petry
Abstract: The fretting is responsible for many failures of components in the industry. It is present in assemblies like rivet and screw fixture, dovetailjoint, shaft and hub with key, and all connections of two bodies with a contact force and a small induced relative displacement. Topic of studies for decades, the researchers perform experimental tests with some simplification in order to accelerate the phenomenon, some times using standard devices or creating dedicated machines for better representing the behavior of the desired components. There are a few studies with thin sheets, in which the fretting fatigue has more impact because a small reduction of the cross section due to the wear of crack results in a significant increase of stress and rate of crack propatation, decresing the number of cycles until failure. In this work, it wasbuild a device to generate the fretting fatigue with two different shape of contact pad. The specimen is a stainless steel sheet thickness 0.152mm, which fractures and surfaces were analyzed using the SEM and white light interferometer to understand the fractures.
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