Search results for "Fatigue"

Virtual reality as a recovering environment - Implications for design principles

2020

In this study, a simulated, VR-based environment was built and analyzed to explore if a VR environment can possess recovering effects. 61 university students tested a VR application depicting a forest and answered survey questions about the experience. The results showed that VR-environment can indeed have recovering effects. Moreover, when comparing to previous studies in real forests, the recovery effects were at similar levels. The study results suggest that as the VR-based environments can possess recovery effects, they can work as recovery environments at schools or similar environments. The study results offer implications for the designers and propose design principles to build recov…

Modelling of thermal stresses in bearing steel structure generated by electrical current impulses

2018

This work is the study of one particular candidate for white etching crack (WEC) initiation mechanism in wind turbine gearbox bearings: discharge current impulses flowing through bearing steel with associated thermal stresses and material fatigue. Using data/results from previously published works, the authors develop a series of models that are utilized to simulate these processes under various conditions/local microstructure configurations, as well as to verify the results of the previous numerical studies. Presented models show that the resulting stresses are several orders of magnitude below the fatigue limit/yield strength for the parameters used herein. Results and analysis of models …

A computational framework for low-cycle fatigue in polycrystalline materials

2021

Abstract A three-dimensional framework for low-cycle fatigue analysis of polycrystalline aggregates is proposed in this work. First, a cohesive law coupling plasticity and damage is developed for modelling cycle-by-cycle degradation of material interfaces up to complete de-cohesion and failure. The law may model both quasi-static degradation under increasing monotonic load and degradation under cyclic loading, through a coupled plasticity-damage model whose activation and flow rules are formulated in a thermodynamically consistent framework. The proposed interface laws have been then implemented and coupled with a multi-region boundary element formulation, with the aim of analysing low-cycl…

The need for recovery scale

2013

Abstract Introduction Need for Recovery scale is one of the main scales used to assess work-induced fatigue and quality of workers’ recovery time. In fact, need for recovery is considered relevant as a precursor of prolonged fatigue or psychological distress, an indicator of work stress, and a mediating or moderating characteristic in the etiology of work-related health problems, sick leave and work disability. Objective The purpose of the present study is to translate the Need for Recovery scale into Italian, and to adapt it to Italian culture; until now there has been no comparable valid instrument made for the Italian language that measures the need for recovery of employees. The stabili…

COVID-19 Pandemic: Prevention and protection measures to be adopted at the workplace

2020

Introduction: SARS-CoV-2, identified in Wuhan, China, for the first time in December 2019, is a new viral strain, which has not been previously identified in humans; it can be transmitted both by air and via direct and indirect contact; however, the most frequent way it spreads is via droplets. Like the other viruses belonging to the same family of coronaviruses, it can cause from mild flu-like symptoms, such as cold, sore throat, cough and fever, to more severe ones such as pneumonia and breathing difficulties, and it can even lead to death. Since no effective specific drug therapy has been found yet, nor any vaccine capable of limiting the spread of this pathogen, it is important for way…

Narratiiviset resurssit, diskurssit ja luovuus kirjoittaen kerrotuissa identiteeteissä jatkosodan aikaisissa kirjeissä

2013

Relations between cavitation erosion resistance of materials and their fatigue strength under random loading

1999

Abstract The paper contains results of tests on fatigue strength under uniaxial random loading and cavitation erosion resistance for three steels: 10HNAP, 18G2A and 15G2ANb. The obtained fatigue and cavitation characteristics were used for determination of relations between these two phenomena. From the analysis it appears that there is correlation between fatigue strength of the material under random loading and its cavitation erosion resistance. It has been shown that fatigue tests under random loading and tests on cavitation erosion of 10HNAP, 18G2A and 15G2ANb steels may be described with a mathematical model of the same type. It has been also found that there is a linear relation, in t…

FATIGUE FAILURE CRITERIA FOR MATERIALS UNDER RANDOM TRIAXIAL STATE OF STRESS

1984

SUMMARY Five fatigue failure criteria are formulated for a random triaxial state of stress whose components have zero mean values. It is assumed that fatigue failure is determined by the stress and strain components that act on an expected fracture plane. It is shown that in some special cases the proposed failure theories reduce to classical theories applied for sinusoidal stresses.

Model Free Control for muscular force by Functional Electrical Stimulation using pulse width modulation

2016

International audience; Functional Electrical Stimulation (FES) is a useful technique for restoring functions for patients with neurological disorders. Muscle activities can be artificially driven through delivery of electrical pulses to skeletal muscles. Typically, muscles are activated by using constant stimulation train with a fixed parameters (amplitude, frequency and pulse width). In addition, the FES systems do not adapt the parameters stimulation to obtain a desired force response during the rehabilitation session. The purpose of this study is to investigate a real-time FES system for adapting automatically the stimulation parameters (stimulation pulse width) to track a desired force…

The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity.

2016

The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s(-1), and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p0.05, Hedge's g = 4.27). Both measures were highl…