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Article
Publication date: 18 October 2018

Zhicheng Huang, Jean-Yves Dantan, Alain Etienne, Mickaël Rivette and Nicolas Bonnet

One major problem preventing further application and benefits from additive manufacturing (AM) nowadays is that AM build parts always end up with poor geometrical quality…

Abstract

Purpose

One major problem preventing further application and benefits from additive manufacturing (AM) nowadays is that AM build parts always end up with poor geometrical quality. To help improving geometrical quality for AM, this study aims to propose geometrical deviation identification and prediction method for AM, which could be used for identifying the factors, forms and values of geometrical deviation of AM parts.

Design/methodology/approach

This paper applied the skin model-based modal decomposition approach to describe the geometrical deviations of AM and decompose them into different defect modes. On that basis, the approach to propose and extend defect modes was developed. Identification and prediction of the geometrical deviations were then carried out with this method. Finally, a case study with cylinders manufactured by fused deposition modeling was introduced. Two coordinate measuring machine (CMM) machines with different measure methods were used to verify the effectiveness of the methods and modes proposed.

Findings

The case study results with two different CMM machines are very close, which shows that the method and modes proposed by this paper are very effective. Also, the results indicate that the main geometrical defects are caused by the shrinkage and machine inaccuracy-induced errors which have not been studied enough.

Originality/value

This work could be used for identifying and predicting the forms and values of AM geometrical deviation, which could help realize the improvement of AM part geometrical quality in design phase more purposefully.

Details

Rapid Prototyping Journal, vol. 24 no. 9
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 3 April 2017

Zul-Atfi Ismail

Conventional methods practiced by the Development and Facilities Management Unit (UPPF) have faced issues due to management deficiencies and incompetent staff members who…

Abstract

Purpose

Conventional methods practiced by the Development and Facilities Management Unit (UPPF) have faced issues due to management deficiencies and incompetent staff members who were unable to handle facilities management assessment processes at Malaysian Polytechnics. The paper aims to discuss this issue.

Design/methodology/approach

The prime objective of this paper is to improve the conventional methods which tend to be both cumbersome and ineffective in the UPPF Maintenance Management Systems (MMSs) at Malaysian Polytechnics. Primary data were gathered through interviews to develop the proposed system. Eight Polytechnics were selected based on major problems arising from using conventional methods. A comparison was then conducted to investigate the maintenance management practices at each Polytechnic. There are around 32 Polytechnics in Malaysia and most are using conventional methods.

Findings

The major conclusion drawn from the interview results was that comprehensive MMSs are lacking, specifically those that integrate operation and maintenance (O&M) processes of facilities management and software programming that provides guidelines for decision-making processes. The interview results also revealed irregularities within the Malaysian Polytechnics’ maintenance management database. This paper explores the concepts of Electronic Form Defect Assessment (E-Form Defect Assessment), relational databases and online customer complaints to adapt their role as dynamic maintenance management tools.

Originality/value

The paper concludes that the developed system is able to accommodate recording of data, such as complaints and specific items needed for maintenance, through the internet and intranet. MMSs potentially transform facilities management O&M processes into one of the most sophisticated technologies by providing access to all information published by each Malaysian Polytechnic institution. This technology was established in order to foster financial cooperation with the idea being that Polytechnics which compete with one another become financially interdependent with the goal of promoting successful facilities management in the construction of new facilities and infrastructure.

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Article
Publication date: 31 May 2011

S. Thirunavukkarasu, B.P.C. Rao, G.K. Sharma, Viswa Chaithanya, C. Babu Rao, T. Jayakumar, Baldev Raj, Aravinda Pai, T.K. Mitra and Pandurang Jadhav

Development of non‐destructive methodology for detection of arc strike, spatter and fusion type of welding defects which may form on steam generator (SG) tubes that are in…

Abstract

Purpose

Development of non‐destructive methodology for detection of arc strike, spatter and fusion type of welding defects which may form on steam generator (SG) tubes that are in close proximity to the circumferential shell welds. Such defects, especially fusion‐type defects, are detrimental to the structural integrity of the SG. This paper aims to focus on this problem.

Design/methodology/approach

This paper presents a new methodology for non‐destructive detection of arc strike, spatter and fusion type of welding defects. This methodology uses remote field eddy current (RFEC) ultrasonic non‐destructive techniques and K‐means clustering.

Findings

Distinctly different RFEC signals have been observed for the three types of defects and this information has been effectively utilized for automated identification of weld fusion which produces two back‐wall echoes in ultrasonic A‐scan signals. The methodology can readily distinguish fusion‐type defect from arc strike and spatter type of defects.

Originality/value

The methodology is unique as there is no standard guideline for non‐destructive evaluation of peripheral tubes after shell welding to detect arc strike, spatter and fusion type of welding defects.

Details

International Journal of Structural Integrity, vol. 2 no. 2
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 3 November 2020

Chinmay Roy, Aparna Ghosh and Suman Chatterjee

This paper aims to estimate the relationship between defect structure with gas concentration for use as a gas sensor. The change in defect concentration caused a shift in…

Abstract

Purpose

This paper aims to estimate the relationship between defect structure with gas concentration for use as a gas sensor. The change in defect concentration caused a shift in the Fermi level, which in turn changed the surface potential, which is manifested as the potentiometric response of the sensing element.

Design/methodology/approach

A new theoretical concept based on defect chemistry and band structure was used to explain the experimental gas response of a sensor. The theoretically simulated response was compared with experimental results.

Findings

Understanding the origin of potentiometric response, through the generation of defects and a corresponding shift in Fermi level of sensing surface, by the adsorption of gas. Through this understanding, the design of a sensor with improved selectivity and stability to a gas can be achieved by the study of defect structure and subsequent band analysis.

Research limitations/implications

This paper provides information about various types of surface defects and numerical simulation of material with defect structure. The Fermi energy of the simulated value is correlated with the potentiometric sensor response.

Practical implications

Gas sensors are an integral part of vehicular and industrial pollution control. The theory developed shows the origin of response which can help in identifying the best sensing material and its optimum temperature of operation.

Social implications

Low-cost, reliable and highly sensitive gas sensors are highly demanded which is fulfilled by potentiometric sensors.

Originality/value

The operating principle of potentiometric sensors is analyzed through electron band structure analysis. With the change in measured gas concentration, the oxygen partial pressure changes. This results in a change in defect concentration in the sensing surface. Band structure analysis shows that change in defect concentration is associated with a shift in Fermi level. This is the origin of the potentiometric response.

Details

Sensor Review, vol. 40 no. 6
Type: Research Article
ISSN: 0260-2288

Keywords

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Article
Publication date: 4 January 2011

Stoyan Stoyanov, Tim Tilford, Farid Amalou, Scott Cargill, Chris Bailey and Marc Desmulliez

Nano‐imprint forming (NIF) is a manufacturing technology capable of achieving high resolution, low‐cost and high‐throughput fabrication of fine nano‐scale structures and…

Abstract

Purpose

Nano‐imprint forming (NIF) is a manufacturing technology capable of achieving high resolution, low‐cost and high‐throughput fabrication of fine nano‐scale structures and patterns. The purpose of this paper is to use modelling technologies to simulate key process steps associated with the formation of patterns with sub‐micrometer dimensions and use the results to define design rules for optimal imprint forming process.

Design/methodology/approach

The effect of a number of process and pattern‐related parameters on the quality of the fabricated nano‐structures is studied using non‐linear finite element analysis. The deformation process of the formable material during the mould pressing step is modelled using contact analysis with large deformations and temperature dependent hyperelastic material behaviour. Finite element analysis with contact interfaces between the mould and the formable material is utilised to study the formation of mechanical, thermal and friction stresses in the pattern.

Findings

The imprint pressure, temperature and the aspect ratio of grooves which define the pattern have significant effect on the quality of the formed structures. The optimal imprint pressure for the studied PMMA is identified. It is found that the degree of the mould pattern fulfilment as function of the imprint pressure is non‐linear. Critical values for thermal mismatch difference in the CTE between the mould and the substrate causing thermally induced stresses during cooling stage are evaluated. Regions of high stresses in the pattern are also identified.

Originality/value

Design rules for minimising the risk of defects such as cracks and shape imperfections commonly observed in NIF‐fabricated nano‐structures are presented. The modelling approach can be used to provide insights into the optimal imprint process control. This can help to establish further the technology as a viable route for fabrication of nano‐scale structures and patterns.

Details

Engineering Computations, vol. 28 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 4 July 2016

Tomasz Chady, Ryszard Sikora, Mariusz Szwagiel, Bogdan Grzywacz, Leszek Misztal, Pawel Waszczuk, Michal Szydlowski and Barbara Szymanik

The purpose of this paper is to describe a multisource system for nondestructive inspection of welded elements exploited in aircraft industry developed in West Pomeranian…

Abstract

Purpose

The purpose of this paper is to describe a multisource system for nondestructive inspection of welded elements exploited in aircraft industry developed in West Pomeranian University of Technology, Szczecin in the frame of CASELOT project. The system task is to support the operator in flaws identification of welded aircraft elements using data obtained from X-ray inspection and 3D triangulation laser scanners.

Design/methodology/approach

For proper defects detection a set of special processing algorithms were developed. For easier system exploitation and integration of all components a user friendly interface in LabVIEW environment was designed.

Findings

It is possible to create the fully independent, intelligent system for welds’ flaws detection. This kind of technology might be crucial in further development of aircraft industry.

Originality/value

In this paper a number of innovative solutions (new algorithms, algorithms’ combinations) for defects’ detection in welds are presented. All of these solutions are the basis of presented complete system. One of the main original solution is a combination of the systems based on 3D triangulation laser scanner and X-ray testing.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 October 2003

C. Wrubl, M. Fassin, A. Buffoli and A. Mollica

In the present work, the protective properties of inhibitive pigments in two epoxy‐primers against corrosion of the aluminium alloy 2024T3 in marine atmosphere were…

Abstract

In the present work, the protective properties of inhibitive pigments in two epoxy‐primers against corrosion of the aluminium alloy 2024T3 in marine atmosphere were investigated, the first containing SrCrO4 and the second Zn3(PO4)2. Potentiostatic polarisation and impedance measurement methods were utilised to evaluate, both the spontaneous onset of defects on coated samples and the propagation of a small artificial defect of known dimension applied since the beginning of the test on each sample, during 24 months of exposure to the marine atmosphere. These techniques enabled a quantitative evaluation of the protective efficiency of the two primers to be made, and for the effects of the surface pre‐treatments of the metallic substrate to be investigated.

Details

Anti-Corrosion Methods and Materials, vol. 50 no. 5
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 August 1998

Jaroslav Mackerle

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder…

Abstract

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder metallurgy and composite material processing are briefly discussed. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for 1994‐1996, where 1,370 references are listed. This bibliography is an updating of the paper written by Brannberg and Mackerle which has been published in Engineering Computations, Vol. 11 No. 5, 1994, pp. 413‐55.

Details

Engineering Computations, vol. 15 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 11 June 2018

Halyna Krechkovska, Oleksandra Student, Grzegorz Lesiuk and José Correia

The purpose of this paper is to assess the technical state of old and repair steels of Shukhov’s tower elements after operation during ~ 110 and 70 years of the water…

Abstract

Purpose

The purpose of this paper is to assess the technical state of old and repair steels of Shukhov’s tower elements after operation during ~ 110 and 70 years of the water tower in Nikolaev, basing on their mechanical tests, metallography and fractography investigations.

Design/methodology/approach

For their certification, the fractographic and structural features and mechanical properties (hardness, strength, plasticity and impact toughness) were analyzed. Both the steels under consideration were characterized by low values of hardness and brittle fracture resistance. The mechanical characteristics of the old steel are lower compared with the repair one. It cannot be only explained by the quality of metal rolling. Moreover, the plasticity characteristics of both steels, defined in synthetic acid rain environment, are lower than in the air. Using fractography investigation, the operational damages in the bulk metal in the form of the elements of cleavage fracture in the central part of the fracture surfaces of specimens tested at the hydrogenation condition by synthetic acid rain environment were revealed.

Findings

The results of this study suggested a degradation of steels’ characteristics caused by the development of scattering damages during their operation. Higher relative elongation of the old steel at lower hardness and impact toughness were also evidenced in that. The metallography and fractography investigations also supported this finding.

Originality/value

This original study aimed at characterizing the microstructural and mechanical degradation of mild steels that was collected from Shukhov’s tower structural elements.

Details

International Journal of Structural Integrity, vol. 9 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 22 February 2021

Zhimin Cao, Wenjun Zong, Junjie Zhang, Chunlei He, Jiaohu Huang, Wei Liu and Zhiyong Wei

This paper aims to reveal the tribochemical reaction mechanism on the nano-cutting interface between HMX crystal and diamond tool.

Abstract

Purpose

This paper aims to reveal the tribochemical reaction mechanism on the nano-cutting interface between HMX crystal and diamond tool.

Design/methodology/approach

Molecular dynamics simulation of HMX crystal nano-cutting by the reactive force field is carried out in this paper. The affinity of activated atoms and friction damage at the different interface have been well identified by comparing two cutting systems with diamond tool or indenter. The analyses of reaction kinetics, decomposition products and reaction pathways are performed to reveal the underlying atomistic origins of tribocatalytic reaction on the nano-cutting interface.

Findings

The HMX crystals only undergo damage and removal in the indenter cutting, while they appear to accelerate thermal decomposition in the diamond cutting. the C-O affinity is proved to be the intrinsic reason of the tribocatalytic reaction of the HMX-diamond cutting system. The reaction activation energy of the HMX crystals in the diamond cutting system is lower, resulting in a rapid increase in the decomposition degree. The free O atoms can induce the asymmetric ring-opening mode and change the decomposition pathways, which is the underlying atomistic origins of the thermal stability of the HMX-diamond cutting system.

Originality/value

This paper describes a method for analyzing the tribochemical behavior of HMX and diamond, which is beneficial to study the thermal stability in the nano-cutting of HMX.

Details

Industrial Lubrication and Tribology, vol. 73 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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