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Article
Publication date: 1 May 2001

J.F. Molinari, M. Ortiz, R. Radovitzky and E.A. Repetto

This paper is concerned with the calibration and validation of a finite‐element model of dry sliding wear in metals. The model is formulated within a Lagrangian framework capable…

1732

Abstract

This paper is concerned with the calibration and validation of a finite‐element model of dry sliding wear in metals. The model is formulated within a Lagrangian framework capable of accounting for large plastic deformations and history‐dependent material behavior. We resort to continuous adaptive meshing as a means of eliminating deformation‐induced element distortion, and of resolving fine features of the wear process such as contact boundary layers. Particular attention is devoted to a generalization of Archard’s law in which the hardness of the soft material is allowed to be a function of temperature. This dependence of hardness on temperature provides a means of capturing the observed experimental transition between severe wear rates at low speeds to mild wear rates at high speeds. Other features of the numerical model include: surface evolution due to wear; finite‐deformation J2 thermoplasticity; heat generation and diffusion in the bulk; non‐equilibrium heat‐transfer across the contact interface; and frictional contact. The model is validated against a conventional test configuration consisting of a brass pin rubbing against a rotating steel plate.

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Engineering Computations, vol. 18 no. 3/4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 25 November 2019

Rohit Pethe, Thomas Heuzé and Laurent Stainier

The purpose of this paper is to present a variational mesh h-adaption approach for strongly coupled thermomechanical problems.

48

Abstract

Purpose

The purpose of this paper is to present a variational mesh h-adaption approach for strongly coupled thermomechanical problems.

Design/methodology/approach

The mesh is adapted by local subdivision controlled by an energy criterion. Thermal and thermomechanical problems are of interest here. In particular, steady and transient purely thermal problems, transient strongly coupled thermoelasticity and thermoplasticity problems are investigated.

Findings

Different test cases are performed to test the robustness of the algorithm for the problems listed above. It is found that a better cost-effectiveness can be obtained with that approach compared to a uniform refining procedure. Because the algorithm is based on a set of tolerance parameters, parametric analyses and a study of their respective influence on the mesh adaption are carried out. This detailed analysis is performed on unidimensional problems, and a final example is provided in two dimensions.

Originality/value

This work presents an original approach for independent h-adaption of a mechanical and a thermal mesh in strongly coupled problems, based on an incremental variational formulation. The approach does not rely on (or attempt to provide) error estimation in the classical sense. It could merely be considered to provide an error indicator. Instead, it provides a practical methodology to adapt the mesh on the basis of the variational structure of the underlying mathematical problem.

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Engineering Computations, vol. 37 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 April 1995

Daphna Birenbaum‐Carmeli

Western countries have invested considerable resources in efforts aimed at reducing the amount of cigarette smoking in their countries, along with its accompanying hazards. Canada…

130

Abstract

Western countries have invested considerable resources in efforts aimed at reducing the amount of cigarette smoking in their countries, along with its accompanying hazards. Canada is no exception to this challenge and takes pride in its participation in the global quest:

Details

International Journal of Sociology and Social Policy, vol. 15 no. 4/5
Type: Research Article
ISSN: 0144-333X

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Article
Publication date: 1 April 2005

Jaroslav Mackerle

Ceramic materials and glasses have become important in modern industry as well as in the consumer environment. Heat resistant ceramics are used in the metal forming processes or…

5158

Abstract

Purpose

Ceramic materials and glasses have become important in modern industry as well as in the consumer environment. Heat resistant ceramics are used in the metal forming processes or as welding and brazing fixtures, etc. Ceramic materials are frequently used in industries where a wear and chemical resistance are required criteria (seals, liners, grinding wheels, machining tools, etc.). Electrical, magnetic and optical properties of ceramic materials are important in electrical and electronic industries where these materials are used as sensors and actuators, integrated circuits, piezoelectric transducers, ultrasonic devices, microwave devices, magnetic tapes, and in other applications. A significant amount of literature is available on the finite element modelling (FEM) of ceramics and glass. This paper gives a listing of these published papers and is a continuation of the author's bibliography entitled “Finite element modelling of ceramics and glass” and published in Engineering Computations, Vol. 16, 1999, pp. 510‐71 for the period 1977‐1998.

Design/methodology/approach

The form of the paper is a bibliography. Listed references have been retrieved from the author's database, MAKEBASE. Also Compendex has been checked. The period is 1998‐2004.

Findings

Provides a listing of 1,432 references. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.

Originality/value

This paper makes it easy for professionals working with the numerical methods with applications to ceramics and glasses to be up‐to‐date in an effective way.

Details

Engineering Computations, vol. 22 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 12 April 2022

Jonathan Kimmitt, Vesna Mandakovic and Pablo Muñoz

Social entrepreneurs engage in action because social entrepreneurs want to solve social problems. Consequently, to see more social entrepreneurship in contexts with the most…

629

Abstract

Purpose

Social entrepreneurs engage in action because social entrepreneurs want to solve social problems. Consequently, to see more social entrepreneurship in contexts with the most severe social problems is expected. This paper argues that this is an oversimplification of the problem-action nexus in social entrepreneurship and that action does not necessarily correspond to the observed scale of social problems. Drawing on the theoretical framing of crescive conditions, this relationship is affected by forms of public investment as institutions that distinctively promote engagement and public interest amongst social entrepreneurs. Thus, this paper assesses the relationship between varying levels of social problems and social entrepreneurship action (SEA) and how and to what extent public investment types – as more and less locally anchored crescive conditions – affect this relationship.

Design/methodology/approach

The hypotheses are tested with a series of random-effects regression models. The data stem from the Global Entrepreneurship Monitor's (GEM) 2015 social entrepreneurship survey and Chile's 2015 National Socioeconomic Characterisation Survey (CASEN). The authors combined both data sets and cross-matched individual-level data (action and investment) with commune-level data (social problem scale) resulting in unique contextualised observations for 1,124 social entrepreneurs.

Findings

Contrary to current understanding, this study finds that SEA is positively associated with low-social problem scale. This means that high levels of deprivation do not immediately lead to action. The study also finds that locally anchored forms of investment positively moderate this relationship, stimulating action in the most deprived contexts. On the contrary, centralised public investment leads to increased social entrepreneurial action in wealthier communities where it is arguably less needed.

Originality/value

The findings contribute to the literature on SEA in deprived contexts, social and public investment as well as policy-level discussion and broader issues of entrepreneurship and social problems.

Details

International Journal of Entrepreneurial Behavior & Research, vol. 28 no. 6
Type: Research Article
ISSN: 1355-2554

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Article
Publication date: 24 July 2007

Rita G. Toscano and Eduardo N. Dvorkin

This paper aims to develop a simple and efficient shell element for large strains hyper‐elastic analyses.

997

Abstract

Purpose

This paper aims to develop a simple and efficient shell element for large strains hyper‐elastic analyses.

Design/methodology/approach

Based on the classical MITC4 shell element formulation a 3D shell element with finite strain kinematics is developed. The new quadrilateral shell element has five dof per node and two global dof to model the thickness stretching. The shell element is implemented for hyperelastic material models and the application of different hyperelastic constitutive relations is discussed.

Findings

The results obtained considering three of the hyperelastic material models available in the literature are quite different when the developed strains are relatively high; this indicates that, for analyzing actual engineering examples, experimental data should be used to decide on the most suitable constitutive relation.

Originality/value

The 3D version of the MITC4 element was developed.

Details

Engineering Computations, vol. 24 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 3 October 2016

Govindarajan Narayanan

The misaligned condition in splines coupling brings more relative motion between the engaging tooth surface and subsequently a rise of wear phenomenon. The sliding friction…

192

Abstract

Purpose

The misaligned condition in splines coupling brings more relative motion between the engaging tooth surface and subsequently a rise of wear phenomenon. The sliding friction between the spline surfaces and initial gap between the teeth are the key roles in wear behaviour in both crowned and straight splines. The paper aims to discuss these issues.

Design/methodology/approach

There is a design constraint to include fretting and wear damage of spline surface in design criteria. It becomes very essential to use a finite element tool to evaluate the wear behaviour of spline surface in order to design for severe environmental conditions. The fretting fatigue and fretting wear damage mechanisms on the spline surfaces are mainly dependent on the forces between the spline surfaces and relative movement between the teeth. This study focusses on the effect of sliding friction coefficients on the wear damage of the spline surfaces based on mating condition.

Findings

Analysis shows that the contact pressure and root stress increase with increasing friction coefficient and misalignment. This is irrelevant to the crowned type of splines. This case becomes worst when the spline has more misaligned condition.

Originality/value

The fretting wear damage of straight spline is essential criterial for the application in aero engines and the crowned spline under controlled misaligned condition provides better wear life compared to straight spline surfaces.

Details

International Journal of Structural Integrity, vol. 7 no. 5
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 2 January 2018

Maarten Otter, Constance Stumpel and Therese van Amelsvoort

The purpose of this paper is to establish the value of clinical genetic diagnostics in the lives of people with an intellectual disability (ID), their families, and their primary…

203

Abstract

Purpose

The purpose of this paper is to establish the value of clinical genetic diagnostics in the lives of people with an intellectual disability (ID), their families, and their primary and professional caregivers. It has been shown that psychologists are more likely to make use of the opportunities offered by clinical genetic diagnostics if they have seen the psychological benefits in their own practice. Moreover, this paper aims to promote the practice of informing people with ID, their families, and other caregivers regarding the current technological advances in genetic diagnostics, thereby allowing these patients to decide for themselves whether to utilise these opportunities.

Design/methodology/approach

The authors report four case studies in which the psychosocial value to each patient is pivotal.

Findings

In these four cases, it is clear the medical model can augment the social model by providing an interpretation of its meaningfulness in the lives of the people concerned.

Research limitations/implications

Case studies alone can have limited scientific significance. This approach examining the significance of clinical genetic diagnosis should be studied further in larger groups.

Practical implications

It is hoped that psychologists and other professional caregivers will become enthused about the value of clinical genetic diagnostics and will choose to discuss the option of referral for clinical genetic diagnostics with their patients more often.

Social implications

People with an ID who are seeking mental health care, and their caregivers, should be given the opportunity to take part in the decision regarding whether to use clinical genetic diagnostics, which may even have a destigmatising effect.

Originality/value

Quality of life may improve for people with an ID seeking mental healthcare and for their caregivers as well by opening up discussion regarding the opportunities presented by clinical genetic diagnostics. The fact that people are able to make their own choices based on their own considerations can have a destigmatising effect.

Details

Advances in Mental Health and Intellectual Disabilities, vol. 12 no. 1
Type: Research Article
ISSN: 2044-1282

Keywords

Available. Open Access. Open Access
Article
Publication date: 24 October 2021

Piergiorgio Alotto, Paolo Di Barba, Alessandro Formisano, Gabriele Maria Lozito, Raffaele Martone, Maria Evelina Mognaschi, Maurizio Repetto, Alessandro Salvini and Antonio Savini

Inverse problems in electromagnetism, namely, the recovery of sources (currents or charges) or system data from measured effects, are usually ill-posed or, in the numerical…

569

Abstract

Purpose

Inverse problems in electromagnetism, namely, the recovery of sources (currents or charges) or system data from measured effects, are usually ill-posed or, in the numerical formulation, ill-conditioned and require suitable regularization to provide meaningful results. To test new regularization methods, there is the need of benchmark problems, which numerical properties and solutions should be well known. Hence, this study aims to define a benchmark problem, suitable to test new regularization approaches and solves with different methods.

Design/methodology/approach

To assess reliability and performance of different solving strategies for inverse source problems, a benchmark problem of current synthesis is defined and solved by means of several regularization methods in a comparative way; subsequently, an approach in terms of an artificial neural network (ANN) is considered as a viable alternative to classical regularization schemes. The solution of the underlying forward problem is based on a finite element analysis.

Findings

The paper provides a very detailed analysis of the proposed inverse problem in terms of numerical properties of the lead field matrix. The solutions found by different regularization approaches and an ANN method are provided, showing the performance of the applied methods and the numerical issues of the benchmark problem.

Originality/value

The value of the paper is to provide the numerical characteristics and issues of the proposed benchmark problem in a comprehensive way, by means of a wide variety of regularization methods and an ANN approach.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 40 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 15 March 2022

Gianmarco Lorenti, Ivan Mariuzzo, Francesco Moraglio and Maurizio Repetto

This paper aims to compare stochastic gradient method used for neural network training with global optimizer without use of gradient information, in particular differential…

116

Abstract

Purpose

This paper aims to compare stochastic gradient method used for neural network training with global optimizer without use of gradient information, in particular differential evolution.

Design/methodology/approach

This contribute shows the application of heuristic optimization algorithms to the training phase of artificial neural network whose aim is to predict renewable power production as function of environmental variables such as solar irradiance and temperature. The training problem is cast as the minimization of a cost function whose degrees of freedom are the parameters of the neural network. A differential evolution algorithm is substituted to the more usual gradient-based minimization procedure, and the comparison of their performances is presented.

Findings

The two procedures based on stochastic gradient and differential evolution reach the same results being the gradient based moderately quicker in convergence but with a lower value of reliability, as a significant number of runs do not reach convergence.

Research limitations/implications

The approach has been applied to two forecasting problems and, even if results are encouraging, the need for extend the approach to other problems is needed.

Practical implications

The new approach could open the training of neural network to more stable and general methods, exploiting the potentialities of parallel computing.

Originality/value

To the best of the authors’ knowledge, the research presented is fully original for the part regarding the neural network training with differential evolution.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 41 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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