A computer model for simulation of the wear behaviour in helical gears has been developed. The method used can deal with tooth modifications and different profiles. The authors have studied the effects of wear previously but only in a two-dimensional perspective. The objective of the paper is to compare the wear behaviour of gears using different approaches. The gear teeth in this model are regarded as thin uncoupled slices, the slicing method is valid when the contact area is slender in the rolling direction, which is the case for contacting gear teeth. The pressure distribution on each slice is calculated using the well-known theories of Hertz assuming an infinitely wide line-contact. When the pressure and velocity on the surfaces are known, a modified Archard's wear equation is applied to calculate wear depths on the teeth. The simulation then becomes an initial value problem since a complete mesh cycle is repeated a number of times with gradually changing surfaces due to the wear that is being integrated over each time step.

Simulation of Mild Wear in Helical Gears

Abstract Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology. 

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A review of advances in tribology in 2020–2021

Industrial elevator systems are complex Cyber-Physical Systems operating in uncertain environments and experiencing uncertain passenger behaviors, hardware delays, and software errors. Identifying, understanding, and classifying such uncertainties are essential to enable system designers to reason about uncertainties and subsequently develop solutions for empowering elevator systems to deal with uncertainties systematically. To this end, we present a method, called RuCynefin, based on the Cynefin framework to classify uncertainties in industrial elevator systems from our industrial partner (Orona, Spain), results of which can then be used for assessing their robustness. RuCynefin is equipped with a novel classification algorithm to identify the Cynefin contexts for a variety of uncertainties in industrial elevator systems, and a novel metric for measuring the robustness using the uncertainty classification. We evaluated RuCynefin with an industrial case study of 90 dispatchers from Orona to assess their robustness against uncertainties. Results show that RuCynefin could effectively identify several situations for which certain dispatchers were not robust. Specifically, 93% of such versions showed some degree of low robustness against uncertainties. We also provide insights on the potential practical usages of RuCynefin, which are useful for practitioners in this field.

Are elevator software robust against uncertainties? results and experiences from an industrial case study

This work presents an active control system applied to vibration level reduction in high-performance vertical transport, aiming at improving the passengers’ comfort in high-speed elevators. The control system design includes the use of a Proportional Integral Derivative (PID) control. Three strategies were proposed in order to achieve a 90% reduction in the vibration amplitudes: (I) the consecutive reduction of 90% of the displacements, (II) the consecutive reduction of 90% of the velocity, and (III) the consecutive reduction of 90% of the acceleration. The presentation of these three proposals allows their application for the use of different sensors. The performance of each strategy was evaluated through mathematical modeling and numerical simulations of a vertical transport with 4 degrees of freedom, submitted to excitations arising from rail deformations. Vibration and comfort levels in the cabin were numerically analyzed, taking into account ISO 2631 and BS 6841 standards for elevator lateral acceleration level and comfort level felt by passengers. Numerical simulations showed that the force required to reduce the vibration levels is practically the same for the three proposed strategies. However, strategy (III) – the successive reduction of 90% of acceleration – proved to be more efficient at improving passengers’ comfort level when compared to the other two strategies.

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Active Control System Applied to Vibration Level Control in High-Speed Elevators

Industrial elevator systems are commonly used software systems in our daily lives, which operate in uncertain environments such as unpredictable passenger traffic, uncertain passenger attributes and behaviors, and hardware delays. Understanding and assessing the robustness of such systems under various uncertainties enable system designers to reason about uncertainties, especially those leading to low system robustness, and consequently improve their designs and implementations in terms of handling uncertainties. To this end, we present a comprehensive empirical study conducted with industrial elevator systems provided by our industrial partner Orona, which focuses on assessing the robustness of a dispatcher—that is, a software component responsible for elevators’ optimal scheduling. In total, we studied 90 industrial dispatchers in our empirical study. Based on the experience gained from the study, we derived an uncertainty-aware robustness assessment method (named UncerRobua) comprising a set of guidelines on how to conduct the robustness assessment and a newly proposed ranking algorithm, for supporting the robustness assessment of industrial elevator systems against uncertainties.

Uncertainty-Aware Robustness Assessment of Industrial Elevator Systems

Lubrication analysis and wear mechanism of heavily loaded herringbone gears with profile modifications in full film and mixed lubrication point contacts

Xiaolong Ma

Papers

Lubrication analysis and wear mechanism of heavily loaded herringbone gears with profile modifications in full film and mixed lubrication point contacts

Experimental evaluation of braking pad materials used for high-speed elevator