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Article
Publication date: 7 October 2020

Liang Tian and Yu Luo

The purpose of this paper is to quantitatively investigate the effect of process parameters (including welding current, voltage and speed) and plate thickness on in-plane…

Abstract

Purpose

The purpose of this paper is to quantitatively investigate the effect of process parameters (including welding current, voltage and speed) and plate thickness on in-plane inherent deformations in typical fillet welded joint; meanwhile, the plastic strains remaining in the weld zone are also analyzed under different influencing factors.

Design/methodology/approach

To achieve the purpose of this study, a thermal-elastic-plastic finite element (TEP FE) model is developed to analyze the thermal-mechanical behavior of the T-welded joint during the welding process. Experimental measurements have verified the validity of the established TEP FE model. Using the effective model, a series of numerical experiments are performed to obtain the inherent deformations under the conditions of different influencing factors, and then the calculation results are discussed based on the relevant data obtained.

Findings

Through numerical simulation analysis, it is found that the longitudinal and transverse inherent deformations decrease with the increase of welding speed and plate thickness, whereas as the nominal heat input increases, the inherent deformations increase significantly. The longitudinal shrinkage presents a quasi-linear and nonlinear distribution in the middle and end of the weld, respectively. The plastic strains in the cross section of the T-joint also vary greatly because of the process parameters and plate thickness, but the maximum value always appears near the location of the welding toe, which means that this point faces a relatively large risk of fatigue cracking. The inherent deformations are closely related to the plastic strains remaining in the weld zone and are also affected by many influencing factors such as process parameters and plate thickness.

Research limitations/implications

In this study, relatively few influencing factors such as welding current, voltage, speed and plate thickness are considered to analyze the inherent deformations in the T-welded joint. Also, these influencing factors are all within a certain range of parameters, which shows that only limited applicability can be provided. In addition, only in-plane inherent deformations are considered in this study, without considering the other two out-of-plane components of inherent deformations.

Originality/value

This study can help to expand the understanding of the relationship between the inherent deformations and its influencing factors for a specific form of the welded joint, and can also provide basic data to supplement the inherent deformation database, thereby facilitating further researches on welding deformations for stiffened-panel structures in shipbuilding or steel bridges.

Details

Engineering Computations, vol. 38 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 20 April 2012

Morteza Vatani, Farshad Barazandeh, AbdolReza Rahimi and Amir Sanati Nezhad

In stereolithography (SL), the total exposure absorbed by photopolymer is variable and is a function of height. This phenomenon causes heterogeneous properties and…

Abstract

Purpose

In stereolithography (SL), the total exposure absorbed by photopolymer is variable and is a function of height. This phenomenon causes heterogeneous properties and develops residual stresses during process. Consequently, a pronounced deformation occurs especially when small and more intricate objects are fabricated. The purpose of this paper is to predict this deformation when miniature and complicated parts are fabricated.

Design/methodology/approach

In this paper classical lamination theory is employed to model mechanical properties of layers, layers shrinkage and residual stress growth during SL process. Distortion is predicted based on the developed model.

Findings

Results show that final distortion is proportional to part thickness and it increases exponentially as parts thickness or layers thickness decrease.

Practical implications

To verify the results, several test pieces were built with SLA 5000 machine and SOMOS 11120 resins. Their distortions were measured with video measuring machine (VMM‐3020D machine). The estimation agrees very well with the experimental results (less than 10 per cent error).

Originality/value

The paper considers the heterogeneous properties of SL parts during fabrication process; an item which was ignored in previous researches. This theoretical and experimental study provides useful information about estimation of deformation of SL parts after building. This information helps the SL machine user to select the best parameters when fabricating miniature and intricate features, especially for biomechanics parts.

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Article
Publication date: 8 June 2021

Swapnil Vyavahare, Soham Teraiya and Shailendra Kumar

This paper aims to focus on studying the influence of gradient parameters, namely, thickness coefficient, length coefficient and height ratio of auxetic structure on…

Abstract

Purpose

This paper aims to focus on studying the influence of gradient parameters, namely, thickness coefficient, length coefficient and height ratio of auxetic structure on responses such as strength, stiffness and specific energy absorption (SEA) under compressive loading. Optimization of significant parameters is also performed to maximize responses. Further, efforts have also been made to develop regression models for strength, stiffness and SEA of auxetic structure.

Design/methodology/approach

Central composite design of response surface methodology is used for planning experiments. Auxetic structures of acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) materials are fabricated by the material extrusion (ME) technique of additive manufacturing. Fabricated structures are tested under in-plane uniaxial compressive loading. Grey relational analysis is used for the optimization of gradient parameters of the unit cell of auxetic structure to maximize responses and minimize weight and time of fabrication.

Findings

From the analysis of variance of experimental data, it is found that the compressive strength of auxetic structures increases with a decrease in length coefficient and height ratio. In the case of ABS structures, stiffness increases with a decrease in thickness coefficient and length coefficient, while in the case of PLA structures, stiffness increases with a decrease in length coefficient and height ratio. SEA is influenced by length coefficient and thickness coefficient in ABS and PLA structures, respectively. Based on the analysis, statistical non-linear quadratic models are developed to predict strength, stiffness and SEA. Optimal configuration of auxetic structure is determined to maximize strength, stiffness, SEA and minimize weight and time of fabrication.

Research limitations/implications

The present study is limited to re-entrant type of auxetic structures made of ABS and PLA materials only under compressive loading. Also, results from the current study are valid within a selected range of gradient parameters. The findings of the present study are useful in the optimal selection of gradient parameters for the fabrication of auxetic structures of maximum strength, stiffness and SEA with minimum weight and time of fabrication. These outcomes have wide applications in domains such as automotive, aerospace, sports and marine sectors.

Originality/value

Limited literature is available on studying the influence of gradient parameters of ME manufactured auxetic structure of ABS and PLA materials on responses, namely, strength, stiffness and SEA under compressive loading. Also, no work has been reported on studying the influence of gradient parameters on mechanical properties, weight and time of fabrication of auxetic structures. The present study is an attempt to fulfil the above research gaps.

Details

Rapid Prototyping Journal, vol. 27 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 February 1993

D.J. Williams, D.C. Whalley, O.A. Boyle and A.O. Ogunjimi

This paper presents analytical and computational models of adhesive joints constructed from anisotropic conducting materials. Such materials are becoming increasingly…

Abstract

This paper presents analytical and computational models of adhesive joints constructed from anisotropic conducting materials. Such materials are becoming increasingly important in the construction of fine pitch interconnection, for example the assembly of surface mounted components to printed circuit boards, and are likely to find considerable application in silicon die attach as alternatives to current ‘flip chip’ technologies. The paper presents design models of the mechanical and low frequency electrical behaviour of typical materials and relates these models to manufacturing process parameters.

Details

Soldering & Surface Mount Technology, vol. 5 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 November 2003

M.S. Chandio, H. Matallah and M.F. Webster

A numerical study on the stretching of a Newtonian fluid filament is analysed. Stretching is performed between two retracting plates, moving under constant extension rate…

Abstract

A numerical study on the stretching of a Newtonian fluid filament is analysed. Stretching is performed between two retracting plates, moving under constant extension rate. A semi‐implicit Taylor‐Galerkin/pressure‐correction finite element formulation is employed on variable‐structure triangular meshes. Stability and accuracy of the scheme is maintained up to large Hencky‐strain levels. A non‐uniform radius profile, minimum at the filament mid‐plane, is observed along the filament‐length at all times. We have found maintenance of a suitable mesh aspect‐ratio around the mid‐plane region (maximum stretch zone) to restrict early filament break‐up and consequently solution divergence. As such, true transient flow evolution is traced and the numerical results bear close agreement with the literature.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 13 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 1 August 2003

D. Peric´ and W. Dettmer

This work is concerned with the computational modelling of non‐linear solid material behaviour in the finite strain regime. Based on the recent computational formulations…

Abstract

This work is concerned with the computational modelling of non‐linear solid material behaviour in the finite strain regime. Based on the recent computational formulations for modelling of inelastic material behaviour, a generalized material model is presented for inelastic materials incorporating classical elastic, viscoelastic, plastic and viscoplastic material description, all operating in the finite strain regime. The underlying rheological model corresponds to the combined action of several rheological components, such as Hooke, Maxwell and Prandtl elements, arranged in parallel. This work summarizes the theoretical basis of the material model and presents the computational treatment in the framework of a finite element solution procedure. Numerical examples are provided to illustrate the scope of the described computational strategy.

Details

Engineering Computations, vol. 20 no. 5/6
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 24 August 2018

Mengistu Gelaw, Perumalla Janaki Ramulu, Dagmawi Hailu and Tariku Desta

The purpose of this paper is to manufacture an aluminium square cross-sectional bar by using conventional lathe machine from aluminium scraps through friction stir back…

Abstract

Purpose

The purpose of this paper is to manufacture an aluminium square cross-sectional bar by using conventional lathe machine from aluminium scraps through friction stir back extrusion (FSBE) process and study the viability of the process to produce the square bar.

Design/methodology/approach

The important tasks involved in this work are as follows: designing and manufacturing the chamber and plunger components used for experimental work, experimentally studying the thermo-mechanical progression of FSBE process on adapted conventional lathe machine and analyzing the relation between controlled parameter (like rotational speed and consolidation time) and response parameter (like extrusion time, extrusion rate, grain structure and hardness).

Findings

Preliminary results show that increasing or decreasing rotational speeds results in defects. Cold crack and twisting defect were shown on square bar fabricated using low rotational speed, and hot crack defects were observed on surface of the bars produced by higher rotational speed. The manufactured square bars were tested using optical microscope and Vickers hardness tester. Microstructural studies reveal that initial grains of aluminium wire undergo significant refinement and result in equiaxed and recrystallized grains in the square bar fabricated through FSBE method. The hardness tests show almost even distribution of hardness in the specimen, but hardness was lower than parent aluminium; in comparison, uneven distribution of hardness was seen in parent aluminium.

Originality/value

FSBE process is the new method to produce the bars and rods with better mechanical properties. The ambition of this work is to convert the existing scrap materials to useful products. Based on the literature review, the work has planned to perform extrusion process with the minimum effort and limited sources. In this manner, the work is highly original and under scientific mandate.

Details

Journal of Engineering, Design and Technology, vol. 16 no. 4
Type: Research Article
ISSN: 1726-0531

Keywords

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Article
Publication date: 17 October 2017

Omar Ahmed Mohamed, Syed Hasan Masood and Jahar Lal Bhowmik

The purpose of this paper is to investigate the effect of process parameters of fused deposition modelling (FDM) 3D printing process on viscoelastic responses (creep…

Abstract

Purpose

The purpose of this paper is to investigate the effect of process parameters of fused deposition modelling (FDM) 3D printing process on viscoelastic responses (creep compliance and recoverable compliance) of FDM built parts using a novel experimental design technique.

Design/methodology/approach

As part of the process characterization, a recently developed class of three-level design methodology – definitive screening design (DSD) – was used in this study to fit a second-order polynomial regression model. Artificial neural network (ANN) was also used to determine the optimal process parameters to improve creep compliance and recoverable compliance. The relationship between layer thickness, air gap, raster angle, build orientation, road width, number of contours and creep performance of FDM fabricated part was thereafter established empirically. Scanning electron microscope (SEM) is used to examine and characterize the morphology of the structures for some samples.

Findings

This study found that the creep resistance of FDM-manufactured part is significantly influenced by layer thickness, air gap, raster angle and number of contours and it can be improved by optimizing the settings of the selected parameters. The relationship between FDM process parameters and creep properties was determined, with the best creep performance observed by using 0.127 mm of layer thickness, zero air gap, zero raster angle, build orientation of 17.188°, road width of 0.4572 mm and 10 contours. Finally, the result is verified by confirmation experiments. The results prove that a DSD is a very effective design in characterizing the influence of process parameters on creep properties of FDM-built part at the lowest cost.

Originality/value

The originality of this paper lies in characterizing and optimizing the effect of process parameters on creep performance of FDM manufactured part that has not been studied in all previous studies. The paper highlights, for the first time, how the application of DSD can overcome most of the limitations encountered in the conventional techniques. This study can be used as a guide to the different additive manufacturing users of various industries and the results provide a good technical database on how FDM process parameters influence the creep performance of manufactured parts.

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Article
Publication date: 1 March 1993

H.E. Evans, P.M. Harvey, J.L. Dabroski and G.O. Dearing

Reliability evaluations for new electronic components and assemblies regularly require extensive test cycles that are both time consuming and costly. Objectives of such…

Abstract

Reliability evaluations for new electronic components and assemblies regularly require extensive test cycles that are both time consuming and costly. Objectives of such test batteries are to identify failure mechanisms and the relationship between these mechanisms and product design or processing features. Optimisation of these critical factors or process steps results in optimised reliability. Statistically designed experiments can facilitate the optimisation process by minimising the amount of testing needed to identify factors affecting reliability, and by providing insight into how these factors can be specified to ensure optimum product design. Designed experimentation was utilised in this study to look at product design and process factors affecting the reliability of inner leads for tape automated bonding (TAB) components. Four factors are considered: outer lead compliancy; chip immobilisation; downset; and tape stiffness and rigidity. Experimental details and results are presented which assess the relative importance of these factors in determining ultimate inner lead reliability, and also provide guidance for final product design considerations.

Details

Circuit World, vol. 19 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 February 1988

W. Stein

Description of the vacuum press process with comparisons made between the isostatic gas pressure and hydraulic press technologies: advantages of the former: materials for…

Abstract

Description of the vacuum press process with comparisons made between the isostatic gas pressure and hydraulic press technologies: advantages of the former: materials for flexible and flexi‐rigid circuit production in the vacuum press.

Details

Circuit World, vol. 14 no. 3
Type: Research Article
ISSN: 0305-6120

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