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Article
Publication date: 23 July 2020

Henadeera Arachchige Ayomi Enoka Perera and Wilathgamuwage Don Gamini Lanarolle

Thermoplastic polymer fabrics are normally heat set to make them dimensionally stable. These fabrics in garment panel form may again be exposed to heat during the…

Abstract

Purpose

Thermoplastic polymer fabrics are normally heat set to make them dimensionally stable. These fabrics in garment panel form may again be exposed to heat during the processes such as bonding, sublimation printing and cause to change their dimensions. The purpose of this paper is to investigate the response of polyester yarns in knitted fabrics to heat setting and post-heat treatments.

Design/methodology/approach

In this study, the thermal shrinkage behaviour of heat set polyester knitted fabrics when subjected to post-heat treatment processes are analyzed using differential scanning calorimetry (DSC) and analysis of fabric shrinkage. DSC is a thermo-analytical technique that measures the difference in the amount of heat needed to increase the temperature of the sample and the reference. A heat flux versus temperature curve is one of the results of a DSC experiment. The polymer structure and morphology of polyester heat-treated and post-heat–treated fabrics were determined by examining the DSC thermograms.

Findings

Heat setting and post-heat setting causes the effective temperature of polyester to change. Effective temperature occurred around 160°C for fabrics heat set at low temperatures and increases as the heat setting temperature increases. Post-heat treatments cause to elevate the effective temperature. Shrinkage of fabrics below the effective temperature is not statistically significant while the shrinkage at higher temperatures is significant. Effective temperature is the main determinant of thermal shrinkage behaviour of polyester.

Originality/value

The study reveals the significance of the effective temperature of polyester on heat treatments and post-heat treatments. The study revealed that heat-setting temperature is a primary determinant of the thermal stability of polyester fabric that are subjected to heat treatments.

Details

Research Journal of Textile and Apparel, vol. 24 no. 4
Type: Research Article
ISSN: 1560-6074

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Article
Publication date: 17 March 2020

Chang Xu, Shifei Shen, Ming Fu and Yayun Li

Bench scale and flame manikin tests are two typical methods to evaluate thermal protective performance (TPP) of fire protective clothing. However, flame manikin test is…

Abstract

Purpose

Bench scale and flame manikin tests are two typical methods to evaluate thermal protective performance (TPP) of fire protective clothing. However, flame manikin test is limited to be widely used for its complication and high cost. The purpose of this paper is to develop a method to evaluate the thermal performance of protective clothing from the bench scale test results and garment parameters, which predicts the body burn injuries without conducting flame manikin tests.

Design/methodology/approach

Bench scale and flame manikin tests’ data were collected from the previous research literature and then statistical analysis was performed to quantitatively investigate the correlations between the two test methods. Equations were established to predict the TPP values accounting for the effects of entrapped air gap and thermal shrinkage. Fitting analysis was conducted to analyze the relationship between the predicted TPP values and total burn injury. Finally, a method to predict total burn injury from the TPP values was proposed and validated.

Findings

The results showed that when the TPP value was predicted with the effects of air gap and thermal shrinkage considered, there was an approximate linear relationship between the predicted TPP values and total burn injury from the manikin test. Therefore, the prediction model of burn injury was developed based on the correlation analysis and verified with a generally good accuracy.

Originality/value

This paper presented a new prediction method to evaluate the thermal performance of protective clothing, which saved significant time and cost compared to the conventional methods. It can provide useful information for burn injury prediction of protective clothing.

Details

International Journal of Clothing Science and Technology, vol. 32 no. 4
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 6 December 2019

Ante Džolan, Mladen Kožul, Alen Harapin and Dragan Ćubela

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the…

Abstract

Purpose

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the developed numerical model for the analysis of shrinkage of spatial three-dimensional structures using thermal analogy is presented. Results of the real behavior of structures because of concrete shrinkage using the developed numerical model are compared with the experimental and it is clearly shown that the developed numerical model is an efficient tool in predicting the time-dependent behavior of all concrete structures.

Design/methodology/approach

In this paper, Fib Model Code 2010 to predict shrinkage deformation of concrete is used, and it was incorporated in the three-dimensional numerical model using the thermal analogy. Mentioned three-dimensional numerical model uses the modified Rankine material law to describe concrete behavior in tension and modified Mohr-Coulomb material law to describe concrete behavior in compression. The developed three-dimensional numerical model successfully analyzes the behavior of reinforced and/or prestressed concrete structures including time-dependent deformations of concrete as well.

Findings

Results are shown in this paper clearly demonstrate the reliability of the developed numerical model in predicting the shrinkage strain, as well as its impact on concrete and reinforced concrete structures. The results obtained using the developed numerical model are in better agreement with the experimental results, than the results obtained using the numerical models from literature that also use the Fib Model Code 2010 to predict the shrinkage strain. So, it can be concluded that for a real simulation of concrete structures, alongside the model for predicting the shrinkage strain, the models for concrete behavior in tension and compression have a very important role.

Originality/value

Results of the developed three-dimensional numerical model were compared with experimental results from literature and with theoretical foundations, and it can be talked that this numerical model presents a good tool for analysis of reinforced and prestressed concrete structures including shrinkage deformation of concrete. Results obtained using the developed three-dimensional numerical model are better agreed with experimental than results of other numerical model from literature.

Details

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

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Article
Publication date: 1 September 1999

Hiroyuki Narahara, Fumiki Tanaka, Takeshi Kishinami, Satoru Igarashi and Katsumasa Saito

In the industrial use of stereolithography, precision is always a problem. The basic phenomenon of solidification shrinkage has not been sufficiently investigated. This…

Abstract

In the industrial use of stereolithography, precision is always a problem. The basic phenomenon of solidification shrinkage has not been sufficiently investigated. This study aims at clarifying the initial linear shrinkage of cured resin in a minute volume. Experimental equipment has been developed which measures the time history of the single strand in situ in a stereolithography machine. An analysis model of the time history of a minute volume linear shrinkage was shown using the measured shrinkage of a cured line segment. The relation between the time history of the linear shrinkage and temperature was measured and the shrinkage in the minute volume after irradiation was found to result due to temperature variation. Deformation and linear shrinkage were measured with two scanning orders to control the thermal distribution in layer forming. The effects of thermal distribution were also observed in one layer forming.

Details

Rapid Prototyping Journal, vol. 5 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 16 April 2018

Meng Deng, Yunyi Wang and Peijing Li

The purpose of this paper is to provide the details of developments to research works in the distribution characteristics of the air gaps within firefighters’ clothing and…

Abstract

Purpose

The purpose of this paper is to provide the details of developments to research works in the distribution characteristics of the air gaps within firefighters’ clothing and research methods to evaluate the effect of air gaps on the thermal protective performance of firefighters’ clothing.

Design/methodology/approach

In this paper, the distribution of air gaps within firefighters’ clothing was first analyzed, and the air gaps characteristics were summarized as thickness, location, heterogeneity, orientation and dynamics. Then, the evaluation of the air gap on the thermal protective performance of fighters’ clothing was reviewed for both experimental and numerical studies.

Findings

The air gaps within clothing layers and between clothing and skin play an important role in determining the thermal protective performance of firefighters’ protective clothing. It is obvious that research works on the effects of actual air gaps entrapped in firefighters’ clothing on thermal protection are comparatively few in number, primarily focusing on static and uniform air gaps at the fabric level. Further studies should be conducted to define the characteristic of air gap, deepen the understand of mechanism of heat transfer and numerically simulate the 3D dynamic heat transfer in clothing to improve the evaluation of thermal protective performance provided by the firefighters’ clothing.

Practical implications

Air gaps within thermal protective clothing play a crucial role in the protective performance of clothing and provide an efficient way to provide fire-fighting occupational safety. To accurately characterize the distribution of air gaps in firefighters’ clothing under high heat exposure, the paper will provide guidelines for clothing engineers to design clothing for fighters and optimize the clothing performance.

Originality/value

This paper is offered as a concise reference for researchers’ further research in the area of the effect of air gaps within firefighters’ clothing under thermal exposure.

Details

International Journal of Clothing Science and Technology, vol. 30 no. 2
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 1 December 2001

George Stylios

Discusses the 6th ITCRR, its breadth of textile and clothing research activity, plus the encouragement given to workers in this field and its related areas. States that…

Abstract

Discusses the 6th ITCRR, its breadth of textile and clothing research activity, plus the encouragement given to workers in this field and its related areas. States that, within the newer research areas under the microscope of the community involved, technical textiles focuses on new, ‘smart’ garments and the initiatives in this field in both the UK and the international community at large. Covers this subject at length.

Details

International Journal of Clothing Science and Technology, vol. 13 no. 6
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 1 April 2005

Hong Wenbin, Lee Yong Tsui and Gong Haiqing

To investigate the “staircase effect”, which is one of the most significant manifestations of part inaccuracy in liquid‐based rapid prototyping (RP) processes, on…

Abstract

Purpose

To investigate the “staircase effect”, which is one of the most significant manifestations of part inaccuracy in liquid‐based rapid prototyping (RP) processes, on multi‐layer RP parts made using a thick layer deposition and photo‐curing process in a stepless rapid prototyping (SRP) system.

Design/methodology/approach

The building of a five‐layer part is simulated layer by layer using a finite element method based on an incremental elastic model, to analyze the staircase effect due to shrinkage induced by polymerization and temperature variation. The influence of various factors such as layer thickness and intensity of incident UV light is studied. The results were verified experimentally.

Findings

Results show that the staircase amount increases 20 percent and 300 percent with light intensity increasing from 65 to 145 mW/cm2 and layer thickness increasing from 0.2 to 2.0 mm, respectively. It is also found that the overall staircase is below 100 μm, which suggests that the SRP process improves surface quality greatly compared to other RP systems, and can provide enough accuracy for fabricating functional parts.

Research limitations/implications

The results apply only to the material used in the work: an acrylate‐based photopolymer resin, C123, produced by Tianjin Chemical Co., China. Also, the thickness of the layers is fixed at 6 mm.

Practical implications

Provides a method to analyze the origin and amount of the staircase effect, upon which to better control the surface finish of RP parts. New materials and different layer thicknesses can be investigated using the same method.

Originality/value

Apart from the above practical implication, this paper establishes the parameters that influence the shrinkage of the material used in SRP.

Details

Rapid Prototyping Journal, vol. 11 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 20 April 2015

Brian N. Turner and Scott A Gold

The purpose of this paper is to critically review the literature related to dimensional accuracy and surface roughness for fused deposition modeling and similar…

Abstract

Purpose

The purpose of this paper is to critically review the literature related to dimensional accuracy and surface roughness for fused deposition modeling and similar extrusion-based additive manufacturing or rapid prototyping processes.

Design/methodology/approach

A systematic review of the literature was carried out by focusing on the relationship between process and product design parameters and the dimensional and surface properties of finished parts. Methods for evaluating these performance parameters are also reviewed.

Findings

Fused deposition modeling® and related processes are the most widely used polymer rapid prototyping processes. For many applications, resolution, dimensional accuracy and surface roughness are among the most important properties in final parts. The influence of feedstock properties and system design on dimensional accuracy and resolution is reviewed. Thermal warping and shrinkage are often major sources of dimensional error in finished parts. This phenomenon is explored along with various approaches for evaluating dimensional accuracy. Product design parameters, in particular, slice height, strongly impact surface roughness. A geometric model for surface roughness is also reviewed.

Originality/value

This represents the first review of extrusion AM processes focusing on dimensional accuracy and surface roughness. Understanding and improving relationships between materials, design parameters and the ultimate properties of finished parts will be key to improving extrusion AM processes and expanding their applications.

Details

Rapid Prototyping Journal, vol. 21 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 21 March 2016

Alkhair Almabrouk Mousa

This paper aims to investigate the curling behaviour of selective laser sintered polyamide/glass bead composites with changes in material compositions, part bed…

Abstract

Purpose

This paper aims to investigate the curling behaviour of selective laser sintered polyamide/glass bead composites with changes in material compositions, part bed temperature, powder base thickness, laser power and layer cooling time.

Design/methodology/approach

The Taguchi parameter design method (design of experiments, DOE) and analysis of variance (ANOVA) technique were applied in the investigation to determine the optimal process parameter settings.

Findings

The results of statistical analysis and ANOVA provided evidence for the effectiveness of filler content and its surface treatment on reducing the amount of curling.

Research limitations/implications

Warping and curling phenomena is one of several aspects of this work that can be pursued further. The present investigation could be expanded to explore other fillers and interface adhesion using other modifiers. Experiments could be conducted with other complicated geometries, various sizes, different positions and locations to widen the knowledge base of geometric accuracy of selective laser sintering process.

Practical implications

This experimental work is beneficial for materials development and accuracy characterisation in rapid manufacturing techniques. The experimental techniques adopted are readily transferable to virtually any material system used in rapid manufacturing.

Originality/value

Although many materials have been developed, there is still a need for research into new materials. This work demonstrates that it is possible to improve the geometric accuracy of selective laser sintered components from glass bead- filled polyamide 12 and achieve near-zero curling by adding rigid multiphase-coated particle to the material system.

Details

Rapid Prototyping Journal, vol. 22 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 11 October 2011

Zhenggang Zhu and Michael Kaliske

The purpose of this paper is to present a numerical model of coupled heat, moisture transfer and their effects on the mechanical deformations of wood during the drying process.

Abstract

Purpose

The purpose of this paper is to present a numerical model of coupled heat, moisture transfer and their effects on the mechanical deformations of wood during the drying process.

Design/methodology/approach

Coupling among heat, moisture, and mechanical deformations is solved consecutively by use of sparse solver of MATLAB. The weighted residual of the equilibrium equations of drying process of wood, based on finite element method, is investigated. The stress and plastic strain increments can be solved with Newton's method.

Findings

The numerical model is applied to a plain strain problem of a long wood board taken from the outer region of the wood log. Numerical simulation reveals the stress reversal during the drying process. The mechanical deformations and the principle stresses of a three‐dimensional wood board in consideration of the orthotropic properties are presented.

Originality/value

Plane strain and plane stress are analysed. The tangential modulus is derived. The transformation of the stress and strain tensors between the local coordinate system resulting from the cylindrical properties of wood and the global one is evaluated. Selection of element type for temperature, moisture content and displacement is discussed.

Details

Engineering Computations, vol. 28 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

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