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Article
Publication date: 13 November 2020

Ji Youjun, K. Vafai, Huijin Xu and Liu Jianjun

This paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low-permeability…

Abstract

Purpose

This paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low-permeability reservoir. The numerical simulation method was used to analyze the process of injected water channeling into the interlayer.

Design/methodology/approach

Some typical cores including the sandstone and the mudstone were selected to test the permeability and the stress sensitivity, and some curves of the permeability varying with the stress for the cores were obtained to demonstrate the sensitivity of the formation. Based on the experimental results and the software Eclipse and Abaqus, the main injection parameters to reduce the amount of the injected water in flowing into the interlayer were simulated.

Findings

The results indicate that the permeability of the mudstone is more sensitive to the stress than sandstone. The injection rate can be as high as possible on the condition that no crack is activated or a new fracture is created in the development. For the B82 block of Daqing oilfield, the suggested pressure of the production pressure should be around 1–3MPa, this pressure must be gradually reached to get a higher efficiency of water injection and avoid damaging the casing.

Originality/value

This work is beneficial to ensure stable production and provide technical support to the production of low permeability reservoirs containing an interlayer.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 April 1988

Roy Bailey

Stress damages us and our performance. It is a real part of most manager's experience and can be said to occur when significant demands exceed perceived management…

1891

Abstract

Stress damages us and our performance. It is a real part of most manager's experience and can be said to occur when significant demands exceed perceived management responsibilities and routines. Stress can be the essence of working life, and certainly need not always be damaging to us. But when it becomes excessive, it is something unwanted.

Details

International Journal of Manpower, vol. 9 no. 4
Type: Research Article
ISSN: 0143-7720

Keywords

Article
Publication date: 1 April 2002

Philip Dewe and Michael O’Driscoll

Presents a report of research which surveyed managers’ views on stress, their beliefs about stress interventions and who should be responsible for addressing job‐related stress

14697

Abstract

Presents a report of research which surveyed managers’ views on stress, their beliefs about stress interventions and who should be responsible for addressing job‐related stress problems. Stress management interventions have embedded in them a range of practices that offer opportunities for individual development and employee wellbeing. Equally, though, there is a strongly‐held belief that many interventions fall short, because they offer only a partial solution or fail to recognize the wider contextual‐structural issues within which organisational behaviour takes place. One reason for this may be that little attempt has been made to find out what managers understand by stress and the extent to which they think that their organisation has a responsibility to address problems of stress. Both qualitative and quantitative techniques were used to explore these issues, using a sample of 540 New Zealand managers. The results draw attention to a number of issues including: do managers’ views of stress reflect acknowledged definitions? Who should assume responsibility for managing stress? What do managers mean when they indicate that an intervention is effective? Are stress interventions any different from standard human resource practices and is there a role for theory in stress interventions?

Details

Personnel Review, vol. 31 no. 2
Type: Research Article
ISSN: 0048-3486

Keywords

Article
Publication date: 1 March 1986

Theodore Sussman and Klaus‐Jürgen Bathe

We describe a visual method—stress band plots—for displaying the stress solution within a two‐dimensional finite element mesh. The stress band plots differ from conventional stress

162

Abstract

We describe a visual method—stress band plots—for displaying the stress solution within a two‐dimensional finite element mesh. The stress band plots differ from conventional stress contour plots because stress band plots display unaveraged stresses (the stresses are computed directly from the solution variables) and stress discontinuities in the finite element solution are directly displayed. Stress band plots are useful in judging the accuracy of a finite element solution, in the comparison of different finite element solutions and during mesh refinement. These uses are demonstrated in an axisymmetric pressure vessel analysis.

Details

Engineering Computations, vol. 3 no. 3
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 1 November 2000

P.M. McDermott and Y.W. Kwon

An algorithm for stable transient solutions was developed for a non‐linear constitutive model for void growth and nucleation with elasto‐plastic deformation of plate structures…

Abstract

An algorithm for stable transient solutions was developed for a non‐linear constitutive model for void growth and nucleation with elasto‐plastic deformation of plate structures under bending loads. The Gurson model was used for void growth and plastic deformation. The constitutive model was incorporated into a plate element which includes both transverse shear and normal deformations. Numerical examples were provided to test the algorithm and to show the effects of the transverse normal deformation and void on plastic strains in plate structures.

Details

Engineering Computations, vol. 17 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 7 August 2017

Susana Rodrigues, Mariana Kaiseler, Cristina Queirós and Miguel Basto-Pereira

Police in Europe are facing increased demands and diminished resources, and this is particularly prominent among emergency response officers (EROs) working in poorer countries…

Abstract

Purpose

Police in Europe are facing increased demands and diminished resources, and this is particularly prominent among emergency response officers (EROs) working in poorer countries such as Portugal. Considering that daily stress and limited coping skills can result in detrimental consequences for officers’ health and society welfare, the purpose of this paper is to investigate stress and coping among Portuguese EROs.

Design/methodology/approach

EROs completed daily diaries over 11 working days. Each diary entry included an open-ended stressor, coping section and a Likert-type scale to evaluate coping effectiveness. Data were analyzed using inductive and deductive content analysis procedures. The frequency of stressors, coping and coping effectiveness were calculated.

Findings

EROs reported facing more operational stressors, particularly public disorder situations. However, gun situations were perceived as the most intense stressor. Emotion-focused coping (i.e. peer support) was more used than problem-focused. Despite variation in coping effectiveness in accordance to stressor experienced, longitudinal analysis suggests that problem-focused coping is more effective.

Research limitations/implications

Longitudinal methodologies should contemplate stress appraisal and coping effectiveness in order to fully understand stress and coping. Future studies should employ this methodology at a larger scale and over longer periods.

Practical implications

Intervention programs for EROs should be multidimensional, targeting work conditions and resources, stress management, and coping effectiveness.

Originality/value

Findings provide strong recommendations for future research and applied implications for stress prevention and effective coping interventions.

Details

International Journal of Emergency Services, vol. 6 no. 2
Type: Research Article
ISSN: 2047-0894

Keywords

Article
Publication date: 1 May 1993

B. BENNANI, P. PICART and J. OUDIN

Microstructure void volume fraction is taken into account in finite element models developed for large strain elastoplastic problems. Void nucleation rate is related to matrix…

Abstract

Microstructure void volume fraction is taken into account in finite element models developed for large strain elastoplastic problems. Void nucleation rate is related to matrix effective strain rate, void growth to material strain rate and associated elastoplastic potential available for porous material, void coalescence to matrix effective strain rate. The related radial return algorithm is described. Three types of computations are proposed: first, axisymmetric Q4 element traction are given as validation example; second, collar cylinder compression are computed as reference example; third, bulk forming are analysed as large strain specific example. Void volume fraction and hydrostatic stress are mainly discussed according to microvoids nucleation, growth and coalescence. Finally, the main interests of those computations are enhanced.

Details

Engineering Computations, vol. 10 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 December 2000

Ramin Moshfegh, Xiangdong Li and Larsgunnar Nilsson

Two mesh refinement indicators based on the gradients of effective stress (GSIG) and effective plastic strain (GEPS), respectively, are proposed for adaptive finite element…

Abstract

Two mesh refinement indicators based on the gradients of effective stress (GSIG) and effective plastic strain (GEPS), respectively, are proposed for adaptive finite element analysis of the large deformation, quasi‐static or dynamic response of shell structures. The mesh refinement indicators are based on equi‐distributing the variation of stresses or plastic strains over the elements of the mesh. A program module is developed and implemented in the non‐linear explicit finite element code LS‐DYNA. This module provides element‐wise refinement evaluations so that selective mesh refinements are carried out in regions of the mesh where the values of local indicators exceed a user‐specified tolerance. The FE model of a conventional deep drawing process is used as a numerical model, including both material and geometrical non‐linearities, in order to demonstrate the versatility of the two refinement indicators. Four different refinement indicators, based on angle change, thickness change, GSIG and GEPS, are applied in this investigation. The numerical results are compared with experimental results regarding the thickness distribution versus cup height, cup height variation versus circumference angle, effective plastic strain in the deformed sheet and punch force. It is shown that the proposed indicators can identify finite elements which have high gradients of effective stress or effective plastic strain so that the mesh is refined in the regions undergoing the most severe deformations and the numerical results are improved.

Details

Engineering Computations, vol. 17 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 March 1997

S.‐W. Lee and J.H. Lau

This paper presents a non‐linear numerical study to investigate the effectof chip dimension and substrate thickness on the solder joint reliability of plastic ball grid…

220

Abstract

This paper presents a non‐linear numerical study to investigate the effect of chip dimension and substrate thickness on the solder joint reliability of plastic ball grid array (PBGA) packages. The package under investigation was a 225‐pin full‐grid PBGA assembly. The diagonal cross‐section of the PBGA together with the printed circuit board (PCB) was modelled by plane‐strain elements. A uniform thermal loading was applied and the solder joints were stressed due to the mismatch of coefficient of thermal expansion (CTE) and constructions of the PCB assembly. The effective stress and accumulated plastic strain of solder balls against various chip dimensions and substrate thicknesses were evaluated as an index for the reliability of solder joints. The results of this study are helpful for electronics packaging engineers to optimise the geometry of plastic ball grid array packages.

Details

Circuit World, vol. 23 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 30 September 2014

Asghar Zajkani, Abolfazl Darvizeh and Mansour Darvizeh

The purpose of this paper is to introduce a computational time dependent modeling to investigate propagation of elastic-viscoplastic zones in the shock wave loaded circular…

Abstract

Purpose

The purpose of this paper is to introduce a computational time dependent modeling to investigate propagation of elastic-viscoplastic zones in the shock wave loaded circular plates.

Design/methodology/approach

Constitutive equations are implemented incrementally by the Von-Kármán finite deflection system which is coupled with a mixed strain hardening rule and physical-base viscoplastic models. Time integrations of the equations are done by the return mapping technique through the cutting-plane algorithm. An integrated solution is established by pseudo-spectral collocation methodology. The Chebyshev basis functions are utilized to evaluate the coefficients of displacement fields. Temporal terms are discretized by the Houbolt marching method. Spatial linearizations are accomplished by the quadratic extrapolation technique.

Findings

Results of the center point deflections, effective plastic strain and stress (dynamic flow stress) and temperature rise are compared for three features of the Von-Kármán system. Identifying time history of resultant stresses, propagations of the viscoplastic plastic zones are illustrated for two circumstances; with considering strain rate and hardening effects, and without them. Some of modeling and computation aspects are discussed, carefully. When the results are compared with experimental data of shock wave loadings and finite element simulations, good agreements between them are observed.

Originality/value

This computational approach makes coupling the structural equations with the physical descriptions of the high rate deformation through step-by-step spectral solution of the constitutive equations.

Details

Engineering Computations, vol. 31 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

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