Search results

1 – 10 of over 30000
Article
Publication date: 26 November 2018

Xiaogang Zhang and Yali Zhang

This study aims to investigate the sliding friction behaviour and mechanism of engineering surfaces.

Abstract

Purpose

This study aims to investigate the sliding friction behaviour and mechanism of engineering surfaces.

Design/methodology/approach

A new numerical approach is proposed. This approach derives the macroscale friction coefficient from microscale asperity interactions. By applying this approach, the sliding friction behaviour under different operating conditions were investigated in terms of molecular and mechanical components.

Findings

Numerical results demonstrate an independent relationship between normal load and friction coefficient, which is governed by the saturated plastic ratio. Numerical results also demonstrate that under very small load, an increase in load increases the friction coefficient. In addition, numerical results confirm the existence of optimal surface roughness where the friction coefficient is the lowest. For the surface profiles used in the current calculation, an optimal surface roughness value is obtained as Rq = 0.125 μm.

Originality/value

This new approach characterizes the deterministic relationship between macroscale friction coefficient and microscale asperity molecular/mechanical interactions. Numerical results facilitate the understanding of sliding friction mechanism.

Details

Industrial Lubrication and Tribology, vol. 71 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 24 June 2019

Jan Karthaus, Benedikt Groschup, Robin Krüger and Kay Hameyer

Due to the increasing amount of high power density high-speed electrical machines, a detailed understanding of the consequences for the machine’s operational behaviour and…

Abstract

Purpose

Due to the increasing amount of high power density high-speed electrical machines, a detailed understanding of the consequences for the machine’s operational behaviour and efficiency is necessary. Magnetic materials are prone to mechanical stress. Therefore, this paper aims to study the relation between the local mechanical stress distribution and magnetic properties such as magnetic flux density and iron losses.

Design/methodology/approach

In this paper, different approaches for equivalent mechanical stress criteria are analysed with focus on their applicability in electrical machines. Resulting machine characteristics such as magnetic flux density distribution or iron are compared.

Findings

The study shows a strong influence on the magnetic flux density distribution when considering the magneto-elastic effect for all analysed models. The influence on the iron loss is smaller due to a high amount of stress-independent eddy current loss component.

Originality/value

The understanding of the influence of mechanical stress on dimensions of electrical machines is important to obtain an accurate machine design. In this paper, the discussion on different equivalent stress approaches allows a new perspective for considering the magneto-elastic effect.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 2 August 2017

Zahid Hussain Hulio and Wei Jiang

The purpose of this paper is to analyze wind climate parameters and performance functions, on the basis of two years of data, and reliability of Pakistan’s first wind farm…

Abstract

Purpose

The purpose of this paper is to analyze wind climate parameters and performance functions, on the basis of two years of data, and reliability of Pakistan’s first wind farm located at Jhimpir, Sindh.

Design/methodology/approach

The methodology covers assessment of wind climate parameters including wind variation at different hub heights, wind shear and diurnal wind shear. In addition, a performance assessment of a wind farm on the basis of technical and real availability, capacity factor and failure rate of mechanical and electrical components has been conducted. The Weibull method has been used for reliability analysis. The maintenance model is proposed for improving the performance. Last is about annual energy volume lost and of financial constraints’ assessment.

Findings

The monthly mean wind variation at heights of 80, 60 and 30 m was found to be 8, 6.9 and 5.9 m/s, respectively. The monthly mean wind shear coefficient was found to be 0.2419. The performance assessment of the wind farm includes technical and real availability, and the capacity factor was found to be 97, 90 and 35.5 per cent, respectively. The failure rate found in the first and second year was 8 and 14 per cent, respectively. Reliability decreased from the first year to the second year, i.e. 0.89 to 0.71 per cent. The components’ failure frequency rose to 57.2 per cent in the second year. The lost energy production due to electrical and mechanical failures was 27.241 GWh in two years that cost Pakistani Rs. 329.8m.

Originality/value

The results of the assessment show that a wind farm needs drastic maintenance strategies to maximize the its performance.

Article
Publication date: 5 May 2015

Fabien Hospital, Marc Budinger, Aurélien Reysset and Jean-Charles Maré

This paper aims to propose preliminary design models of actuator housing that enable various geometries to be compared without requiring detailed knowledge of the actuator…

Abstract

Purpose

This paper aims to propose preliminary design models of actuator housing that enable various geometries to be compared without requiring detailed knowledge of the actuator components. Aerospace actuation systems are currently tending to become more electrical and fluid free. Methodologies and models already exist for designing the mechanical and electrical components, but the actuator housing design is still sketchy.

Design/methodology/approach

The approach is dedicated to linear actuators, the most common in aerospace. With special attention paid to mechanical resistance to the vibratory environment, simplified geometries are proposed to facilitate the generation of an equivalent formal development. The vibratory environment imposes the sizing of the actuator housing. Depending on the expected level of details and to vibration boundary conditions, three levels of modeling have been realized.

Findings

This paper shows that the vibrations induced by aircraft environment are not design drivers for conventional hydraulic actuators but can be an issue for new electromechanical actuators. The weight of the latter can be optimized through a judicious choice of the diameter of the housing.

Practical implications

This approach is applied to a comparison of six standard designs of linear actuator geometries after validation of the consistency of the different models. Early conclusions can be drawn and may lead to design perspectives for the definition of actuator architecture and the optimization of the design.

Originality/value

This paper has demonstrated the importance of the vibratory environment in the design of linear actuator housing, especially for electro-mechanical actuators with important strokes. Developed analytical models can be used for the overall design and optimization of these new aerospace actuators.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 87 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 30 June 2022

Miguel Ángel Caminero, Ana Romero Gutiérrez, Jesús Miguel Chacón, Eustaquio García-Plaza and Pedro José Núñez

The extrusion-based additive manufacturing method followed by debinding and sintering steps can produce metal parts efficiently at a relatively low cost and material…

Abstract

Purpose

The extrusion-based additive manufacturing method followed by debinding and sintering steps can produce metal parts efficiently at a relatively low cost and material wastage. In this study, 316L stainless-steel metal filled filaments were used to print metal parts using the extrusion-based fused filament fabrication (FFF) approach. The purpose of this study is to assess the effects of common FFF printing parameters on the geometric and mechanical performance of FFF manufactured 316L stainless-steel components.

Design/methodology/approach

The microstructural characteristics of the metal filled filament, three-dimensional (3D) printed green parts and final sintered parts were analysed. In addition, the dimensional accuracy of the green parts was evaluated, as well as the hardness, tensile properties, relative density, part shrinkage and the porosity of the sintered samples. Moreover, surface quality in terms of surface roughness after sintering was assessed. Predictive models based on artificial neural networks (ANNs) were used for characterizing dimensional accuracy, shrinkage, surface roughness and density. Additionally, the response surface method based on ANNs was applied to represent the behaviour of these parameters and to identify the optimum 3D printing conditions.

Findings

The effects of the FFF process parameters such as build orientation and nozzle diameter were significant. The pore distribution was strongly linked to the build orientation and printing strategy. Furthermore, porosity decreased with increased nozzle diameter, which increased mechanical performance. In contrast, lower nozzle diameters achieved lower roughness values and average deviations. Thus, it should be noted that the modification of process parameters to achieve greater geometrical accuracy weakened mechanical performance.

Originality/value

Near-dense 316L austenitic stainless-steel components using FFF technology were successfully manufactured. This study provides print guidelines and further information regarding the impact of FFF process parameters on the mechanical, microstructural and geometric performance of 3D printed 316L components.

Details

Rapid Prototyping Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 10 June 2014

Bo Jansen, Eugeni L. Doubrovski and Jouke C. Verlinden

This paper investigates how designers exploit the full potential of additive manufacturing (AM). AM yields a broad range of advantageous properties including the…

Abstract

Purpose

This paper investigates how designers exploit the full potential of additive manufacturing (AM). AM yields a broad range of advantageous properties including the possibility to fabricate mechanical multi-body structures.

Design/methodology/approach

This case study explores the possibilities and limitations in designing mechanical multi-body structures for AM, focused on the development of a selective laser sintering (SLS) version of Theo Jansen’s “Strandbeest” walking mechanism, dubbed Animaris Geneticus Parvus (AGP). We discuss the design process and considerations involved and attempt to distill design guidelines.

Findings

Novel structural solutions were developed to enable SLS fabrication of the AGP, specifically cross-shaped pivot pins, increased clearance between bodies, spacing studs, restricting axial play with pins, partial disassemblies and increased clearance around extremities. The result is a functioning walking mechanism of 74 components can be fabricated at once without human intervention.

Research limitations/implications

This article represents a case study; although it does mention adapted design rules for SLS, its greatest contribution is the holistic approach – to integrate a number of engineering challenges in one prototypical manifestation.

Practical implications

Part consolidation by AM could bring great benefits in future product design applications. The findings show that complex multi-body mechanical structures with more than 70 elements are feasible by AM without assembly. This presents new business opportunities for AM service bureaus and novel product opportunities for designers.

Originality/value

As a case study, this article provides inspiration of the mechanical complexity beyond regular products – from original idea to end result. For researchers, key contribution is the approach in obtaining design optimization strategies which provides engineering designers with a new language to consider SLS.

Article
Publication date: 1 February 1983

K.G. Swift and R.J. Dewhurst

An orientation system incorporating a low power He‐Ne laser system is described. In one application grub screws were fed at rates in excess of 100 per minute

Abstract

An orientation system incorporating a low power He‐Ne laser system is described. In one application grub screws were fed at rates in excess of 100 per minute

Details

Assembly Automation, vol. 3 no. 2
Type: Research Article
ISSN: 0144-5154

Article
Publication date: 24 June 2019

Jan Karthaus, Silas Elfgen and Kay Hameyer

Magnetic properties of electrical steel are affected by mechanical stress. In electrical machines, influences because of manufacturing and assembling and because of…

Abstract

Purpose

Magnetic properties of electrical steel are affected by mechanical stress. In electrical machines, influences because of manufacturing and assembling and because of operation cause a mechanical stress distribution inside the steel lamination. The purpose of this study is to analyse the local mechanical stress distribution and its consequences for the magnetic properties which must be considered when designing electrical machines.

Design/methodology/approach

In this paper, an approach for modelling stress-dependent magnetic material properties such as magnetic flux density using a continuous local material model is presented.

Findings

The presented model shows a good approximation to measurement results for mechanical tensile stress up to 100 MPa for the studied material.

Originality/value

The presented model allows a simple determination of model parameters by using stress-dependent magnetic material measurements. The model can also be used to determine a scalar mechanical stress distribution by using a known magnetic flux density distribution.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 19 April 2013

Francesca Riccobono, Manfredi Bruccoleri and Giovanni Perrone

Many research studies in operations management (OM) and strategic management (SM) investigate how different kinds of firm decisions regarding business relationships can…

Abstract

Purpose

Many research studies in operations management (OM) and strategic management (SM) investigate how different kinds of firm decisions regarding business relationships can positively affect a firm's operations performance, resource endowment, and competitive position. Very few studies exist, however, that have attempted to illuminate the actual behaviors of managers when making strategic decisions about their intercompany relationships; rather, most existing studies focus on normative theory. The purpose of this paper is to explore linkages between the “set” of strategic objectives that managers are willing to pursue, the “set” of networking decisions they make, and the “set” of business agreements they sign.

Design/methodology/approach

In order to investigate and explore actual managerial behaviors with respect to networking strategy, the study adopts a field research approach based on multiple case studies. Data were collected on 13 business agreements from three manufacturing firms in the mechatronics industry in Italy. Within‐case and cross‐case analyses are used for theory‐building purposes.

Findings

The empirical data allow identification four different archetypes of networking strategy. The archetypes capture different connections between the “set” of strategic objectives that managers are willing to pursue, the “set” of networking decisions that they consider, and the “set” of strategic agreements that they actually adopt. Specifically, the identified archetypes are named multi‐alignment, multi‐agreement (diversification), multi‐objective, and mono‐alignment (focus), and these are related to different association multiplicities among objectives, decisions, and agreements. The implications related to these archetypes are three‐fold. First, the multi‐alignment archetype suggests a focus not just on one kind of agreement, but also on the firm's overall portfolio of agreements, in order to facilitate understanding of how different kinds of agreements and networking decisions can play a complementary role in achieving a firm's predetermined business objective/s. Second, the multi‐agreement (diversification) archetype suggests that managers can minimize the risk of losing the potentiality of network collaboration by undertaking different kinds of agreements for the same strategic objective. Third, the mono‐alignment (focus) and multi‐objective archetypes suggest that just one agreement can potentially pursue one or multiple strategic objectives, and thus can allow managers to minimize the cost of managing several networking relationships.

Originality/value

The originality of this study lies in its exploration of linkages between objectives, decisions and networking agreements. Unlike most of the existing papers in OM and SM, however, it does not specifically focus on: vertical or horizontal relationships; operations performance (positioning school) or resource endowment (resource‐based view) strategic objectives; or any specific kind of agreement contract (outsourcing, alliance, joint venture, etc.). This paper presents four different networking strategy archetypes that represent different ways of matching a “set” of networking decisions, strategic objectives and business agreements. These are not related to either vertical or horizontal relationships, operations performance or resource endowment objectives, or any specific contract agreement form.

Article
Publication date: 1 March 1998

David J. Edwards, Gary D. Holt and F.C. Harris

The construction industry relies increasingly on profits generated from high utilisation of mechanisation. Interruption of this mechanical supply not only incurs the…

4294

Abstract

The construction industry relies increasingly on profits generated from high utilisation of mechanisation. Interruption of this mechanical supply not only incurs the “tangible” costs of labour, replacement parts and consumables, but also the less tangible costs of delays to contract, possible loss of client goodwill and ultimately, loss of profit. Cumulative costs associated with plant breakdown are therefore significant. Predictive maintenance (PM) techniques have evolved to keep a check on mechanical health, by generating information on machine condition. Such data allow just in time maintenance to be conducted. However, recent developments have witnessed an increased interest in determining “root cause” of failure as opposed to monitoring the time to breakdown once the wear process has begun. This paper reviews condition based monitoring (CBM) technologies and introduces the evolving concept of root cause analysis. Both these could have particular relevance to construction plant and equipment. In summary, the paper presents initial findings of ongoing research, which is the development of a model for predicting construction plant and equipment breakdown.

Details

Journal of Quality in Maintenance Engineering, vol. 4 no. 1
Type: Research Article
ISSN: 1355-2511

Keywords

1 – 10 of over 30000