Search results for "TRES"
showing 10 items of 6927 documents
Magnetorheology for suspensions of solid particles dispersed in ferrofluids
2006
In this work, the magnetorheological properties of suspensions of micron-sized iron particles dispersed in magnetite ferrofluids were studied. With this aim, the flow properties of the suspensions in the steady-state regime were investigated using a commercial magnetorheometer with a parallel-plate measuring cell. The effect of both magnetite and iron concentration on the magnitude of the yield stress was studied for a broad range of magnetic fields. In addition, the experimental values of the yield stress were compared with the predictions from the chain model. With this purpose the values of the yield stress were obtained by means of finite element calculations. Interestingly, it was foun…
On the mechanisms involved in the tensile strength of a dissimilar Ti6Al4V/316L laser welded assembly
2021
International audience; The aim of the present work is to analyze the thermomechanical behavior of dissimilar laser seams by means of FE modeling. The case of a Ti6Al4V/316L assembly with vanadium insert was considered. Effective mechanical properties of the main materials and cords were first estimated from NHT measurements. Modeling of the double pass laser welding process was performed first by considering shrinking of the two weld seams during manufacturing, to get the residual stress state in the welded assembly. Modeling of the tensile test was performed in a second step to study the assembly behavior during loading. In these modeling results, the mesh was the cross-section of the mic…
Impact of Superfinish Turning on Surface Integrity of Pure Copper
2011
Abstract The presented study deals with comprehension of relationships between machining cutting conditions and physical-chemical properties linked with surface integrity. A multi-physics model is presented to calculate residual stress, temperature and dislocation fields in the machined material. This model includes both thermal-mechanical, structural evolution and dynamic recristallisation approaches. The model was applied to pure copper after superfinish turning. Good agreement was found between numerical values and experimental ones. This paper also presents a work on the impact of mechanical and microstructural changes induced by machining on the electrochemical behaviour and corrosion …
Different Space Charge Behavior of Materials Used in AC and DC Systems
2017
The aim of the present work is to evaluate the behavior, from the space charge accumulation phenomenon point of view, of three different XLPE specimens used as insulation materials in high voltage systems. Considering that under DC stress the charge accumulation is more relevant as compared to the AC case, in the specimens for DC applications additives are typically added. In this work, three different specimens are analyzed. One is a free additive sample used conventionally under AC stress and two others include different additives that are used under DC stress. In order to measure the space charge accumulation, the Pulsed Electro Acoustic (PEA) method has been employed. For each sample, t…
Experimental and numerical study of composite T-joints for marine application
2010
Abstract The aim of this work was to study the behaviour of composite T-joints used in marine applications. The effect of several parameters was investigated. In particular, three configurations were studied; i.e. with adhesive and with two different over-laminations. Moreover, the joined sections were made of different materials. These joints were subjected to a tensile load in the plane of the sheet. To quantify the effect of different designs on the strength, a variance analysis was performed. Finally, a numerical model was developed using a commercial finite element code (Ansys).
The global cracking laws for a finite-element model of no-tension material
1992
Abstract For perfect no-tension materials (NRT) the validity of the local stability postulate of Drucker, well known in plasticity, has been assumed so far and utilized to derive the local cracking laws, which relate cracking strain states and stress states to each other. On this base a finite-element (FE) model with suitable constitutive behaviour for the single FE is presented. Classical FE approaches enforce the cracking laws at the Gauss points of the FEs. In this work it is shown that taking into account cracking strains, suitably modelled, over the whole domain of the FE and making use of an energy approach lead to general cracking laws describing the constitutive behaviour of the who…
A matter of time? Challenging and hindering effects of time pressure on work engagement
2017
ABSTRACTThe aim of our research was to test time-exposure effects of time pressure as a stressor typically considered to be a challenge, rather than a hindrance stressor. We examined the within- and between-person effects of time pressure on work engagement in two diary/panel studies with employees using intervals of five days and three weeks, respectively (Study 1, n = 350, and n = 357, respectively) and six to eight weeks (Study 2, n = 238). We assumed that it is a matter of time whether time pressure acts as a challenge (under short-term exposure) or as a hindrance stressor (under long-term exposure). We found significant positive within-person effects of time pressure on work engagement…
Factors Contributing to Different Agency in Work and Study
2013
Most young adults today are following longer educational tracks and postpone entrance into the workforce. This 2-year study aimed to determine factors contributing to occupational self-efficacy in a representative sample of n = 1,891 young adults ( M = 23.92, SD = 2.17 years) with different work statuses (studying, in an apprenticeship, employed, or unemployed). Occupational identity, perceived work quality, the ability to cope with work stress, and symptomatology were assessed. Path analyses revealed that work status was the most important predictor of later occupational self-efficacy, with employment showing the strongest prediction of later agency in the professional domain. Ruminative e…
Knowledge Management of Work Stress in Mexican Manufacturing Environments
2018
This chapter presents a knowledge management perspective to propose a pair of structural models to determine the relationship between burnout syndrome (BS) and body mass index (BMI) among high and middle managers of Mexican maquiladoras. In developing countries like Mexico there are opportunities to expand burnout study on diversity of contexts and occupations. The Maslach burnout general inventory questionnaire (MB-GI) was used, and sociodemographic data were collected as well as the weight and size of respondents. Instrument shows an acceptable reliability index. Structural equation models are used to determine relationship among variables. From a sample of 361 people, using segmentations…
Work related stress and well-being: the roles of direct action coping and palliative coping
2006
The purpose of the present study is to analyze the roles of direct action coping and palliative coping in the relationship between work stressors and psychological well-being, as well as their possible interactions, in a sample of 464 bank employees. Hierarchical regression analyses showed main effects of direct action coping on well-being. Palliative coping predicts higher levels of psychological distress. Contrary to what was expected, the interactions between work stressors and direct action coping were not significant. Palliative coping interacted with work stressors when predicting psychosomatic complaints. The interaction between the two types of coping was significant on psychosomati…