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Journal ArticleDOI

Fatigue Analysis of Spherical Contact Subjected to Cyclic Elastic-Plastic Normal Loading

01 Jul 2021-Journal of Tribology-transactions of The Asme (American Society of Mechanical Engineers Digital Collection)-Vol. 143, Iss: 7
TL;DR: In this article, the multiaxial Fatemi-Socie fatigue criterion is adopted to study the contact fatigue in a spherical asperity subjected to cyclic elastic-plastic normal loading.
Abstract: Surface fatigue resulting from cyclic contact loading is a main reason for the rough surface wear. Since a rough surface consists of many asperities, the fatigue in one asperity is investigated. The multiaxial Fatemi–Socie fatigue criterion is adopted to study the contact fatigue in a spherical asperity subjected to cyclic elastic-plastic normal loading. The fatigue damage in the asperity is predicted. The maximum fatigue damage occurs at the edge of the maximum contact area. Two typical patterns are found for the fatigue damage distribution. Locations and orientations of fatigue microcrack initiation are also identified. Finally, future research directions are discussed.
Citations
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Journal ArticleDOI
TL;DR: In this article , the effect of lubricant viscosity on dynamics of a high-precision spur gear pair with near-zero backlash was investigated under deterministic and uncertain conditions via a tribo-dynamic model.

10 citations

Journal ArticleDOI
TL;DR: In this paper, a hybrid optimization method was developed for solving many-objective optimization problems of low specific speed centrifugal pumps (LSSCP) in district energy systems to promote the integration of renewable energy.
Abstract: Low specific speed centrifugal pumps (LSSCP) are widely utilized in district energy systems to promote the integration of renewable energy. However, the performance of LSSCP becomes inefficient due to harsh operating conditions resulting in substantial increase in energy consumption. Many-objective optimization is significant in improving the performance of LSSCP and promoting the sustainability of district energy systems. Among the existing optimization methods, global optimization methods are limited by high computational cost when solving many-objective optimization problems, and gradient-based optimization methods face difficulties in locating the global optimum. In the present study, a hybrid optimization method was developed for solving many-objective optimization problems of LSSCP. The LSSCP optimization result of the hybrid algorithm was compared with that of the non-dominated sorting genetic algorithm (NSGA), so as to demonstrate the capacity of the proposed method. In the designed flow condition without cavitation, the hydraulic efficiency obtained by the hybrid optimization algorithm was found to be 9.5%, 5.4%, and 4.7% higher than those of the original, NSGA-II, and NSGA-III optimized results, respectively. The shaft power was 10.3%, 8.7% and 5.1% less than said three optimized results. The maximum turbulent kinetic energy in the flow passage obtained from the hybrid optimization was only 2.2 J/kg, which was 67% and 46% less than that of the NSGA-II and NSGA-III optimized results, respectively. In the designed flow condition with cavitation, the net positive suction head critical optimized by the hybrid model was 0.857 m, which was substantially reduced compared with the original and NSGA- II optimized results.

8 citations

Journal ArticleDOI
01 Jan 2022-Sensors
TL;DR: In this article , a vibration separation methodology compensated by a time-varying transfer function (TVTF-VS) was proposed to diagnose non-hunting tooth planetary gearboxes.
Abstract: Due to planetary movement of planet gears, the vibration signal perceived by a stationary sensor is modulated and difficult to diagnose. This paper proposed a vibration separation methodology compensated by a time-varying transfer function (TVTF-VS), which is a further development of the vibration separation (VS) method in the diagnosis of non-hunting tooth planetary gearboxes. On the basis of VS, multi-teeth VS is proposed to extract and synthesize the meshing signal of a planet gear using a single transducer. Considering the movement regularity of a planetary gearbox, the time-varying transfer function (TVTF) is represented by a generalized expression. The TVTF is constructed using a segment of healthy signal and an evaluation indicator is established to optimize the parameters of the TVTF. The constructed TVTF is applied to overcome the amplitude modulation effect and highlight fault characteristics. After that, experiments with baseline, pitting, and compound localized faults planet gears were conducted on a non-hunting tooth planetary gearbox test rig, respectively. The results demonstrate that incipient failure on a planet gear can be detected effectively, and relative location of the local faults can be determined accurately.

8 citations

Journal ArticleDOI
01 Mar 2021
TL;DR: In this paper, a finite element model of an asperity subjected to cyclic elastic-plastic normal loading was developed under frictionless contact condition, and the multiaxial Fatemi-Socie fatigue criterion was adopted to evaluate the fatigue damage of the Asperity in elastic shakedown state, which was achieved after several loading cycles.
Abstract: Surface fatigue wear widely exists, and it occurs as long as a sufficient number of loading–unloading cycles are applied. Slowing down surface fatigue wear requires understanding the evolution of fatigue damage in the surface. Real surfaces are composed of many asperities; therefore, it is important to study the fatigue damage of a single asperity. A finite element model of an asperity subjected to cyclic elastic–plastic normal loading was developed under frictionless contact condition. The asperity can be either completely or partially unloaded in a loading cycle. For the sake of completeness, both cases were investigated in the present study. The multiaxial Fatemi-Socie fatigue criterion was adopted to evaluate the fatigue damage of the asperity in elastic shakedown state, which was achieved after several loading cycles. For the case of complete unloading, severe fatigue damage was confined in a subsurface ridge starting from the edge of the maximum loaded contact area. The shape and volume of the wear particles were predicted based on a fundamentally valid assumption. For the case of partial unloading, the fatigue damage was much milder. Finally, potential research directions to expand the current study are suggested.

1 citations

Journal ArticleDOI
TL;DR: In this article , a translational-torsional coupled nonlinear tribodynamic model considering local faults is developed to detect incipient faults in a wind turbine planetary gearbox system.
Abstract: In a wind turbine (WT) planetary gearbox system, the characteristics of incipient faults are difficult to recognize with increasing friction under a lack of lubrication condition. To this end, a translational–torsional coupled nonlinear tribodynamic model considering local faults is developed. A fitted time-varying transfer function is obtained using an impact experiment excited by a planet gear with a missing tooth and is further used to represent the modulation effect caused by the carrier. Using the proposed analytical model, the vibration response and modulation mechanism of the resultant signal under the coupling effect of tooth root crack and sliding friction are investigated. It is demonstrated that specific sidebands are greatly excited and the spectrum structure becomes extremely complex after the introduction of friction. Based on these results, sideband indicators are obtained to monitor the lubrication state and detect incipient faults. The experimental results based on an in-house WT drivetrain testbench are in good agreement with the simulation results.

1 citations

References
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Journal ArticleDOI
TL;DR: In this paper, a modification to Brown and Miller's critical plane approach is proposed to predict multiaxial fatigue life under both in-phase and out-of-phase loading conditions.
Abstract: — A modification to Brown and Miller's critical plane approach is proposed to predict multiaxial fatigue life under both in-phase and out-of-phase loading conditions. The components of this modified parameter consist of the maximum shear strain amplitude and the maximum normal stress on the maximum shear strain amplitude plane. Additional cyclic hardening developed during out-of-phase loading is included in the normal stress term. Also, the mathematical formulation of this new parameter is such that variable amplitude loading can be accommodated. Experimental results from tubular specimens made of 1045 HR steel under in-phase and 90° out-of-phase axial-torsional straining using both sinusoidal and trapezoidal wave forms were correlated within a factor of about two employing this approach. Available Inconel 718 axial-torsional data including mean strain histories were also satisfactorily correlated using the aforementioned parameter.

1,493 citations

Journal ArticleDOI
TL;DR: In this paper, a finite element study of elasto-plastic hemispherical contact is presented, and the results are normalized such that they are valid for macro contacts (e.g., rolling element bearings), although micro-scale surface characteristics such as grain boundaries are not considered.
Abstract: This work presents a finite element study of elasto-plastic hemispherical contact. The results are normalized such that they are valid for macro contacts (e.g., rolling element bearings) and micro contacts (e.g., asperity contact), although micro-scale surface characteristics such as grain boundaries are not considered. The material is modeled as elastic-perfectly plastic. The numerical results are compared to other existing models of spherical contact, including the fully plastic truncation model (often attributed to Abbott and Firestone) and the perfectly elastic case (known as the Hertz contact). This work finds that the fully plastic average contact pressure, or hardness, commonly approximated to be a constant factor of about three times the yield strength, actually varies with the deformed contact geometry, which in turn is dependent upon the material properties (e.g., yield strength). The current work expands on previous works by including these effects and explaining them theoretically. Experimental and analytical results have also been shown to compare well with the current work. The results are fit by empirical formulations for a wide range of interferences (displacements which cause normal contact between the sphere and rigid flat) and materials for use in other applications.

558 citations

Journal ArticleDOI
TL;DR: In this paper, the applications of three main types of biocompatible metal, namely, stainless steels, cobalt-chromium alloys, and titanium and its alloys are reviewed.

403 citations

Journal ArticleDOI
TL;DR: In this article, a brief overview of some important issues in multiaxial fatigue and life estimation is presented, including damage mechanisms and damage quantification parameters, material constitutive response and non-proportional hardening, cycle counting and damage accumulation in variable amplitude loading, and mixed-mode crack growth.

298 citations

Journal ArticleDOI
TL;DR: This article focuses on product design stages to investigate what key factors affect product design quality and how it can be controlled and assured, and separately survey key factors affecting product designquality in traditional and crowdsourcing-based design environments.
Abstract: Small and medium-sized enterprises face the challenges that they do not have enough employees and related resources to produce high-quality products with limited budget and time. The emergence of c...

288 citations