Papers by Keyword: Hertzian Contact

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Authors: Taisei Yamada, Hwa Soo Lee, Hideyoshi Matsushita
263
Authors: Katsuyuki Kida, Megumi Uryu, Takashi Honda, Edson Costa Santos, Kenichi Saruwatari
Abstract: Flaking failure of bearings is caused by crack growth and stress concentration. The contact conditions between ball, retainer and race affect the durability of the bearings. Non-destructive methods that can be related to contact conditions are necessary to study and understand the phenomena caused by the contact stresses. In the present work, a scanning Hall probe microscope (SHPM) equipped with a GaAs film sensor was used to observe the asymmetric distribution of three-dimensional magnetic fields in bearing steel plates (JIS-SUJ2) before and after light load contact tests of 19.6N. It was found that only vertical components of the magnetic fields are slightly affected by the spherical Hertzian contact. Furthermore, the change in the three-dimensional magnetic fields is asymmetric to the contact center and magnetization center.
1031
Authors: Katsuyuki Kida, Megumi Uryu, Takashi Honda, Edson Costa Santos, Kenichi Saruwatari
Abstract: Failure of dies and molds is caused by wear and deformation during the metal sheet forming process. Die wear takes various forms, and the contact conditions in die-parts affect the strength of the components. Non-destructive methods that can be related to contact conditions are necessary to study and understand the phenomena caused by the contact stresses. In the present work, a newly developed scanning Hall probe microscope (SHPM) equipped with a GaAs film sensor was used to observe the three-dimensional magnetic fields in tool steel plates before and after contact tests at room temperature in air. It was found that the intensity of three-dimensional magnetic fields is only slightly affected by the spherical Hertzian contact. However, all of the three-dimensional components of the magnetic fields change significantly. The extent of the changes depends not on the distribution of stress under spherical Hertzian contact but on the initial distribution of the magnetic fields.
578
Authors: Chang Ping Zou
Abstract: The advanced actuator is a kind of swaying mechanism specially developed for certain aircraft, having low rotational speed and great torque. Utilizing criterions of mass equivalent and bending stiffness equivalent, this paper firstly applies simplification to the actuator, getting a piece of continuous beam with varying circular sections. According to the mounting condition of actuator, then establishes the finite element dynamic analyzing model, using I-DEAS software, selecting method of synchronous vector iteration, finishes normal modal analyzing. Next, carries Hertzian contact resonance analyses to ball straight-rotary pair, ball spline pair and ball unload pair, calculates contact resonance frequencies. Considering the resistance torque being moving still concludes formulae of quantity of contact resonance frequencies. Lastly, based on load spectra, makes a conclusion that antiresonance behavior of the actuator is well, showing that the design plan is feasible. Experimentation of prototype indicates that the above theoretical analyses are correct.
2410
Authors: Chul Seung Lee, Kee Sung Lee, Shi Woo Lee, Do Kyung Kim
Abstract: Contact damage resistances of silicon nitride ceramics with various grain boundary phases are investigated in this study. The grain boundary phases are controlled by the addition of different types of sintering additives, or the crystallization of intergranular phase in a silicon nitride. We control the microstructures of materials to have similar grain sizes and the same phases to each other. Contact testing with spherical indenters is used to characterize the damage response. The implication is that the grain boundary phase can be another controllable factor against contact damage and strength degradation even though it is not critical relative to the effect of grain morphology.
421
Authors: Katsuyuki Kida, Megumi Uryu, Takashi Honda, Edson Costa Santos, Kenichi Saruwatari
Abstract: Tribological failure of machine components, such as wear and flaking failure is caused by contact stress concentration. However, observation of stress under contact load is a difficult task. Non-destructive methods that can be related to contact conditions are necessary to study and understand the phenomena caused by the contact stresses. In the present work, a scanning Hall probe microscope (SHPM) equipped with a GaAs film sensor was used to observe the three-dimensional magnetic fields in a long square bar specimen (JIS-SUJ2) before and after contact tests at 196N. It was found that the changes in the three-dimensional magnetic fields caused by spherical Hertzian contact are not affected by the location of the magnetization point on the specimen's surface.
103
Authors: Hyun Kyu Jun, Won Hee You
Abstract: Rolling contact fatigue initiated defects such as surface corrugation, head check, squat, are one of growing problems in high speed railway line. A squat is generally developed below the rail surface and grows parallel to surface until it turns down into rail. Estimation of critical crack size and crack growth rate is an essential to prevent rail from failure and develop cost effective railway maintenance strategy. In this study, we predict crack growth rate of a rail with a squat defect. For this purpose, a rail model with a squat defect is developed. Timoshenko’s beam theory is applied to calculate the global bending stress at the crack tip and Hertzian contact model is applied to calculate the local contact stresses at the surface of rail by simulating rolling over a railway wheel on a rail. Stress intensity factors are calculated from the total stress at the crack tip. Fatigue crack growth curve of 60kg rail steel is applied to calculated crack growth rate. Software to predict crack growth life through whole life cycle is developed. We expect that we can make a more cost effective rail maintenance strategy by considering the crack growth analysis for a defective rail.
313
Authors: Zhong Guang Wang, H. Zhang, Q.S. Zang, Zhe Feng Zhang, Z.M. Sun
693
Authors: Zhong Guang Wang, H. Zhang, Q.S. Zang, Zhe Feng Zhang, Z.M. Sun
Abstract: Ti3SiC2 has been widely investigated for their intriguing physical and mechanical properties [1]. In the past decades, dense and pure polycrystalline Ti3SiC2 has been fabricated by some techniques [1,2]. Studies on deformation and fracture behavior at elevated temperature showed that Ti3SiC2 exhibited substantial plasticity with high strength [3]. It is pointed out that Ti3SiC2 can be possibly used for some contact applications, such as bearings, for its relative high compression strength, self-lubricating and machinability [1]. In the present paper, fatigue crack-growth rates and Hertzian contact damage of Ti3SiC2 were studied. Shielding ability of Ti3SiC2 was investigated specially in the small crack region. Damage evolution and strength degradation under Hertzian contact were studied to reveal damage behavior and mechanisms in Ti3SiC2.
849
Authors: Xiao Hui Dong, Hong Wei Zhang, Lei Wang
Abstract: A finite element model with functionally graded materials is established. Furthermore, the distributions of the maximum contact stresses on monolithic substrates under Hertz contact conditions have been analyzed. The effect of the coating thickness is obtained by single-layer coating systems. With increasing the coating thickness, the distribution of maximum radial stress is moved from the coating surface to coating/substrate interface. Meanwhile, the depth of maximum shear stress is moved away from the interface. The location of the maximum shear stress within the multilayer coating systems is not changed. The deformation of the model is more serious with the increase of the applied load.The results can provide some insights regarding the design of the graded coatings in the engineering application.
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