Impact of processing parameters on tensile strength, in-process crystallinity and mesostructure in FDM-fabricated PLA specimens

2019 ◽  
Vol 25 (8) ◽  
pp. 1398-1410 ◽  
Author(s):  
Ognjan Luzanin ◽  
Dejan Movrin ◽  
Vassilis Stathopoulos ◽  
Pavlos Pandis ◽  
Tanja Radusin ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Layer Thickness ◽  
Process Model ◽  
Processing Parameters ◽  
Poly Lactic Acid ◽  
Extrusion Speed ◽  
Plate Temperature ◽  
Content Type ◽  
Designed Experiment ◽  
The Impact

Purpose This study aims to investigate the impact of layer thickness, extrusion temperature, extrusion speed and build plate temperature on the tensile strength, crystallinity achieved during fabrication (herein, in-process crystallinity) and mesostructure of Poly(lactic acid) specimens. Both tensile strength and in-process crystallinity were optimized and verified as the function of processing parameters, and their relationship was thoroughly examined. Design/methodology/approach The four key technological parameters were systematically varied as factors on three levels, using the statistically designed experiment. Surface response methodology was used to optimize tensile strength and crystallinity for the given ranges of input factors. Optimized factor settings were used in a set of confirmation runs, where the result of optimization was experimentally confirmed. Material characterization was performed using differential scanning calorimetry and X-ray diffraction analysis, while the effect of processing parameters on mesostructure was examined by scanning electron microscopy. Findings Layer thickness and its quadratic effect are dominant contributors to tensile strength. Significant interaction between layer thickness and extrusion speed implies that these parameters should always be varied simultaneously within designed experiment to obtain adequate process model. As regards, the in-process crystallinity, extrusion speed is part of two significant interactions with plate temperature and layer thickness, respectively. Quality of mesostructure is vital contributor to tensile strength during FDM process, while the in-process crystallinity exhibited no impact, remaining below the 20 per cent margin regardless of process parameter settings. Originality/value According to available literature, there have been no previously published investigations which studied the effect of process parameters on tensile strength, mesostructure and in-process crystallinity through systematic variation of four critical processing parameters.

Investigating impact of five build parameters on the maximum flexural force in FDM specimens – a definitive screening design approach

2017 ◽  
Vol 23 (6) ◽  
pp. 1088-1098 ◽  
Author(s):  
Ognjan Luzanin ◽  
Vera Guduric ◽  
Ivan Ristic ◽  
Simon Muhic
Keyword(s):  
Layer Thickness ◽  
Extrusion Temperature ◽  
Quadratic Term ◽  
Extrusion Speed ◽  
Content Type ◽  
Screening Design ◽  
Definitive Screening ◽  
The Impact ◽  
Definitive Screening Design ◽  
Deposition Angle

Purpose The purpose of this study was to examine the impact of five key build parameters – layer thickness, deposition angle, infill, extrusion speed and extrusion temperature, and their interactions – on the maximum flexural force in specimens which are made of polylactic acid (PLA). Design/methodology/approach Through a previous study on the flexural properties of PLA specimens, a statistically significant effect of layer thickness was indicated, requiring further experimentation to establish the values of quadratic term in the model, as well as to perform optimization. Instead of performing a conventional Central Composite Design, a novel, definitive screening design (DSD) was used as statistical method. DSD allowed the reduction of the number of runs required for optimization while minimizing aliasing. Findings Significance of deposition angle and infill as main effects was established. Moreover, significant two-way interactions between infill/layer thickness and infill/extrusion speed were detected and discussed. The optimization procedure showed that minimum level of deposition angle, maximum levels of extrusion speed and infill and near mid-level of layer thickness yield maximum flexural force. Research limitations/implications In this study, the three levels of infill were 0.1, 0.2 and 0.3, which corresponds to 10, 20 and 30 per cent of infill, respectively. In everyday practice, infill is usually kept within this range since it allows time-efficiency, i.e. significant reduction of build time. Though, unsurprisingly, higher infill is positively correlated with flexural strength, this study provides practical directions for optimal selection of other key parameters when working with low infill values. Social implications Optimal 3D printing with low infill can contribute to lower material waste and pollution, while PLA plastic’s biodegradability remains high on the environment protection agenda. Originality/value According to available literature, no previous studies have investigated the FDM extrusion of PLA material using a combination of low infill, deposition angle, layer thickness, extrusion speed and extrusion temperature.

Open hole tensile testing of 3D printed parts using in-house fabricated PLA filament

2020 ◽  
Vol 26 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Harshit K. Dave ◽  
Ashish R. Prajapati ◽  
Shilpesh R. Rajpurohit ◽  
Naushil H. Patadiya ◽  
Harit K. Raval
Keyword(s):  
Tensile Strength ◽  
Layer Thickness ◽  
Process Parameters ◽  
Geometrical Shape ◽  
Content Type ◽  
Fused Deposition ◽  
Open Hole ◽  
Raster Angle ◽  
3D Printed ◽  
The Impact

Purpose Fused deposition modeling (FDM) is being increasingly used in automotive and aerospace industries because of its ability to produce specimens having difficult geometrical shape. However, owing to lack of critical information regarding the reliability and mechanical properties of FDM-printed parts at various designs, the use of 3D printed parts in these industries is limited. Therefore, the purpose of this paper is to investigate the impact of process parameters of FDM on the tensile strength of open-hole specimen printed using in-house-fabricated polylactic acid (PLA). Design/methodology/approach In the present study, three process parameters, namely, raster angle, layer thickness and raster width, are selected for investigation of tensile strength. To produce the tensile specimens in the FDM machine, the PLA filament is used which is fabricated from PLA granules using a single-screw extruder. Further, the experimental values are measured and critically analysed. Failure modes under tests are studied using scanning electron microscopy (SEM). Findings Results indicate that the raster angle has a significant effect on the tensile strength of open-hole tensile specimen. Specimens built with 0° raster angle, 200-µm layer thickness and 500-µm raster width obtained maximum tensile strength. Originality/value In this work, a new concept of testing a plate that has a rectangular shape and a circular hole at the centre is tested. Open-hole tensile test standard ASTM D5766 has been implemented for the first time for the FDM process.

scholarly journals The effect of annealing on deformation and mechanical strength of tough PLA and its application in 3D printed prosthetic sockets

2021 ◽  
Vol 27 (11) ◽  
pp. 81-89
Author(s):  
Diede Christine Wijnbergen ◽  
Merel van der Stelt ◽  
Luc Martijn Verhamme
Keyword(s):  
Tensile Strength ◽  
Tensile Test ◽  
Material Properties ◽  
Poly Lactic Acid ◽  
Control Group ◽  
Iso Standard ◽  
Content Type ◽  
Prosthetic Socket ◽  
3D Printed ◽  
The Impact

Purpose Fused filament fabrication (FFF) using tough poly lactic acid (PLA) was determined to be the most suited method to achieve low-cost prosthetic sockets. However, improvement in the material properties is desirable to strengthen these sockets. This study aims to evaluate annealing as a potential method to improve material properties by a heat treatment of the object after 3D printing. Design/methodology/approach Four different annealing methods and a control group were tested according to ISO standard 527–1 and ISO standard 527–2. The four annealing methods included: oven; sand; water; and glycerol annealing. Tests were performed on longitudinal and transversal 3D printed samples. Deformation was determined on 3D printed test rings. Findings Annealing using an oven, sand and water resulted in a significant increase in tensile strength in longitudinally 3D printed tensile test samples. However, the tensile strength was decreased in the transversally 3D printed tensile test samples. The tensile modulus had no significant increase in the longitudinally and transversally printed samples. Sand annealing resulted in the least deformation, with a shrinkage of 2.04% of inner diameter and an increase in height of 1.99% for the horizontally annealed test rings. Research limitations/implications The annealing of prosthetic sockets is not recommended as a decrease in tensile strength in transversally printed tensile test samples was observed. More research is needed towards the strengthening of tough PLA in both print directions. Originality/value This paper fulfils the need for understanding the impact of annealing on 3D printed items intended for daily use, such as a prosthetic socket.

Women and expatriate assignments

2016 ◽  
Vol 38 (2) ◽  
pp. 200-223 ◽  
Author(s):  
Arup Varma ◽  
Linda Russell
Keyword(s):  
Organizational Support ◽  
Multinational Enterprises ◽  
Process Model ◽  
Theoretical Perspective ◽  
Critical Issue ◽  
Critical Determinant ◽  
Content Type ◽  
Female Employees ◽  
Expatriate Assignments ◽  
The Impact

Purpose – The purpose of the paper is twofold – first, to explore the role of perceived organizational support (POS) during the three critical stages of the female expatriate experience, with a view to explaining the disproportionately low numbers of females in expatriate roles; and second, to offer specific suggestions to multi-national enterprises to help them create a level playing field so females can compete for expatriate assignments. Design/methodology/approach – The authors draw upon the theory of POS to explore how the perceived lack of support from their organization during the critical stages of expatriate assignments affects women’s interest, and potentially their performance, in expatriate assignments. The authors develop and present relevant propositions. Findings – This is a conceptual paper that offers a process model of the impact of POS on the three stages of selection of females for expatriates. Research limitations/implications – From a theoretical perspective it is clear that POS can play an important role in the willingness of females to accept international assignments. Thus POS can be a critical determinant of the potential levels of female participation in expatriate assignments. Previously, scholars have argued that the low numbers of female expatriates may be a result of a lack of interest on their part, or because they may not be welcomed in many countries. However, subsequent theses have argued, and many studies have shown, that females can be equally successful. The proposed process model helps to better understand how organizations might dismantle the barriers faced by potential female expatriates, by addressing the key issues at each stage. Practical implications – Multinational enterprises need to ensure that they are drawing from their full pool of talent, if they are to compete effectively against other multinational enterprises. By paying attention to the suggestions, and adopting and executing the propositions, they will be able to avoid the possibility that their qualified female employees may withdraw from the organization if they believe that they are not likely to be considered for expatriate assignments, simply because of their gender, even though they are interested. Social implications – From a societal perspective, it is indeed critical that qualified females are provided the same opportunities that are made available to males. Given that roughly half the population is female, multi-national enterprises that fail to treat their female employees fairly will be seen as poor corporate citizens. Originality/value – This is the first paper to address the critical issue of low numbers of females on expatriate assignments by drawing upon the tenets of the theory of POS. The authors offer several propositions to help multinational enterprises understand the impact of the gender imbalance in expatriate assignments, and offer suggestions on how organizations might improve the participation of females in expatriate assignments.

Happiness and farm productivity: insights from maize farmers in China

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wanglin Ma ◽  
Puneet Vatsa ◽  
Xiaoshi Zhou ◽  
Hongyun Zheng
Keyword(s):  
Process Model ◽  
Agricultural Development ◽  
Well Being ◽  
Farm Size ◽  
Subjective Well Being ◽  
Firm Level ◽  
Content Type ◽  
Maize Productivity ◽  
Farm Productivity ◽  
The Impact

PurposeThe purpose of this study is to explore the relationship between farmers' happiness and farm productivity, taking maize production in China as an example.Design/methodology/approachThe conditional mixed process model is employed to account for the endogeneity that inevitably arises in regression models studying happiness and estimate the 2015 China Household Finance Survey data.FindingsThe empirical results show that a higher level of farmers' happiness is associated with higher maize productivity. The marginal return in maize productivity changes unevenly with increments in farmers' self-reported happiness on a five-point Likert scale. Farmers' happiness is positively determined by their age, educational level, farm size, machinery ownership, access to agricultural subsidy and car ownership. Machinery ownership and access to credit are two important factors that improve maize productivity.Research limitations/implicationsThe finding suggests that promoting the subjective well-being of farmers is conducive to higher productivity and improved national food security. The results have implications for China and other developing countries aiming for sustainable agricultural development.Originality/valueFirm-level data show that workers' happiness improves productivity. However, it is still unclear whether farmworkers' happiness affects farm productivity. Thus, this study provides the first empirical analysis of the impact of farmworkers' happiness on farm productivity.

The impact of implicit bias on business-to-business marketing

2020 ◽  
Vol 35 (10) ◽  
pp. 1517-1525
Author(s):  
Kim Stephens ◽  
Richard L. Baskerville
Keyword(s):  
Process Model ◽  
Minority Groups ◽  
Implicit Bias ◽  
Social Cues ◽  
Relationship Building ◽  
Content Type ◽  
B2b Marketing ◽  
Interactive Workshop ◽  
The Impact ◽  
Business To Business

Purpose Physical social cues can influence the buyer and seller in business-to-business (B2B) marketing. The current behavioural model does not account for the role of implicit bias. The purpose of this paper is to present that relationship and introduce a process model to weaken implicit bias through training with the employment of transformational conversation. Design/methodology/approach With social cues as the predecessor to inferences, there is the potential for implicit bias to derail relationship building in a B2B context. The author’s qualitative field study offers guidance for businesses to make informed decisions about implicit bias training. Findings The study findings show that an interactive workshop following a process model with the addition of transformational conversation can weaken implicit bias. Research limitations/implications The research was conducted with a small cohort of information technology professionals. More research should be done specifically with sellers and buyers in various industries over a longer period of time with periodic follow-up on sales performance and relationship building. Practical implications Minority groups had a combined buying power of $3.9tn in 2018. For sellers to succeed, they have to be able to modulate the implicit biases that interfere with good sales relationships. Originality/value This paper introduces implicit bias as a moderator into the conceptual framework of the behavioural response to social cues in the B2B context and offers a model of implicit bias training using a process model with transformational conversation.

Effect of layer thickness on irreversible thermal expansion and interlayer strength in fused deposition modeling

2017 ◽  
Vol 23 (5) ◽  
pp. 943-953 ◽  
Author(s):  
Anthony A. D’Amico ◽  
Analise Debaie ◽  
Amy M. Peterson
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Flexural Strength ◽  
Layer Thickness ◽  
Fused Deposition Modeling ◽  
Thermal Strain ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
The Impact

Purpose The aim of this paper is to examine the impact of layer thickness on irreversible thermal expansion, residual stress and mechanical properties of additively manufactured parts. Design/methodology/approach Samples were printed at several layer thicknesses, and their irreversible thermal expansion, tensile strength and flexural strength were determined. Findings Irreversible thermal strain increases with decreasing layer thickness, up to 22 per cent strain. Tensile and flexural strengths exhibited a peak at a layer thickness of 200 μm although the maximum was not statistically significant at a 95 per cent confidence interval. Tensile strength was 54 to 97 per cent of reported values for injection molded acrylonitrile butadiene styrene (ABS) and 29 to 73 per cent of those reported for bulk ABS. Flexural strength was 18 to 41 per cent of reported flexural strength for bulk ABS. Practical implications The large irreversible thermal strain exhibited that corresponding residual stresses could lead to failure of additively manufactured parts over time. Additionally, the observed irreversible thermal strains could enable thermally responsive shape in additively manufactured parts. Variation in mechanical properties with layer thickness will also affect manufactured parts. Originality/value Tailorable irreversible thermal strain of this magnitude has not been previously reported for additively manufactured parts. This strain occurs in parts made with both high-end and consumer grade fused deposition modeling machines. Additionally, the impact of layer thickness on tensile and flexural properties of additively manufactured parts has received limited attention in the literature.

Experimental determination of impact tensile properties of adhesive butt joints with the split Hopkinson bar

2003 ◽  
Vol 38 (3) ◽  
pp. 233-245 ◽  
Author(s):  
T Yokoyama
Keyword(s):  
Tensile Strength ◽  
Layer Thickness ◽  
Energy Absorption ◽  
Loading Rate ◽  
Adhesive Layer ◽  
Hopkinson Bar ◽  
Butt Joints ◽  
Cyanoacrylate Adhesive ◽  
Split Hopkinson ◽  
The Impact

The tensile strength and energy absorption of adhesive butt joints at high rates of loading are determined with a tensile split Hopkinson bar using a cylindrical specimen. A commercially available single-component cyanoacrylate adhesive (instantaneous adhesive) and two different adherend materials are used in the adhesion tests. The impact tensile strength of the cyanoacrylate adhesive butt joints is determined from the applied tensile stress history at failure initiation. The impact absorbed energy is obtained by numerical integration of dynamic tensile load-adhesive deformation data. Comparative tension tests at low and intermediate rates of loading are performed on an Instron testing machine. An axisymmetric finite element analysis is carried out to investigate the stress distributions in the adhesive layer of the cyanoacrylate adhesive butt joints. The effects of loading rate, adherend material and adhesive layer thickness on the tensile strength and energy absorption of the cyanoacrylate adhesive butt joints are examined in detail. It is shown that the joint tensile strength increases significantly with increasing loading rate and is greatly affected by both the adhesive layer thickness and the adherend materials. The limitations of the technique are discussed.

Alternative microwave curing approach for imparting ease and care characteristics and antimicrobial activity to viscose fabric

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kh M. Mostafa ◽  
A. A. Elsanabary
Keyword(s):  
Tensile Strength ◽  
Antibacterial Activity ◽  
Citric Acid ◽  
Graft Copolymer ◽  
Crosslinking Agent ◽  
Sodium Hypophosphite ◽  
Content Type ◽  
Microwave Curing ◽  
Recovery Angle ◽  
The Impact

Purpose This study aims to use multi-functional viscose fabric that was facilely developed with with respect to ease and care characteristics, reinforcement effect and antibacterial activity by using novel echo friendly antibacterial finish based on citric acid/sodium hypophosphite and the authors’ previously tailor-made poly meth acrylic acid (MAA)-chitosan graft copolymer via alternative microwave curing approach instead of traditional high-temperature cure one. Design/methodology/approach Viscose fabric was paddled twice in the cross-linking formulations containing different concentrations of citric acid, poly (MAA)-chitosan graft copolymer and sodium hypophosphite to 90 % wet pick up and dried at 100°C for 3 min in an electric oven. Then, the treated fabrics were placed on the disk spinner of the microwave oven and cured at different power (100–800 Watt) for various durations (60–180 s). The fabric was then water-rinsed and dried at ambient condition before use. Findings Results revealed that the above echo friendly method for finished viscose fabrics was found to achieve relatively high dry wrinkle recovery angle and maintain the loss in tensile strength within the acceptable range, as well as antibacterial activity against Escherichia coli and Staphylococcus aureus as a gram-negative and gram-positive bacteria, respectively; in addition to durability up to ten washing cycles. Furthermore, scanning electron microscope images, nitrogen content and add on % of the finished fabric confirmed the penetration of grafted chitosan inside the fabric structure. The tentative mechanism for these reactions is advocated. Originality/value The novelty addressed here is undertaken with the advantages of using citric acid as a nonformaldehyde, safe and cheap poly carboxylic acid as a crosslinking agent and sodium hypophosphite as a potential catalyst, in addition to the authors’ noncitable multifunctional echo friendly tailor-made poly (MAA)-chitosan graft copolymer for imparting reinforcement and antibacterial characteristics to viscose fabric that uses the pad-dry/cure microwave fixation for progressively persuaded heat within the fabric during curing. Research limitations/implications This was done to see the impact of microwave as green and efficient tool with respect to reduction in organic solvents, chemicals and exposer time as well as fixation temperature on the finishing reaction in comparison with traditional pad-dry-cure method. Practical implications Poly (MAA)-chitosan graft copolymer as amphoteric biopolymer was expected to impart multifunctional properties to viscose fabrics especially with comparable dry wrinkle recovery angle and minimize the loss in tensile strength in addition to antibacterial properties in comparison with untreated one.

Tailoring physico-mechanical properties and rheological behavior of ABS filaments for FDM via blending with SEBS TPE

2020 ◽  
Vol 26 (10) ◽  
pp. 1687-1700
Author(s):  
Mozhgan Sayanjali ◽  
Amir Masood Rezadoust ◽  
Foroud Abbassi Sourki
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
3D Printing ◽  
Impact Strength ◽  
Layer Thickness ◽  
Melt Mixing ◽  
Content Type ◽  
Build Orientation ◽  
Raster Angle ◽  
The Impact

Purpose This paper aims to focus on the development of the three-dimensional (3D) printing filaments based on acrylonitrile butadiene styrene (ABS) copolymer and styrene-ethylene/butylene-styrene (SEBS) block copolymer, with tailored viscoelastic properties and controlled flow during the 3D printing process. Design/methodology/approach In this investigation, ABS was blended with various amounts of SEBS via a melt mixing process. Then the ABS/SEBS filaments were prepared by a single-screw extruder and printed by the FDM method. The rheological properties were determined using an MCR 501 from Anton-Paar. The melt flow behavior of ABS/SEBS filaments was determined. The morphology of the filaments was studied by scanning electron microscope and the mechanical (tensile and impact) properties, surface roughness and void content of printed samples were investigated. Findings The rheological results can accurately interpret what drives the morphology and mechanical properties’ changes in the blends. The impact strength, toughness, elongation-at-break and anisotropy in mechanical properties of ABS samples were improved concurrently by adding 40 Wt.% of SEBS. The optimal tensile properties of blend containing 40 Wt.% SEBS samples were obtained at −45°/+45° raster angle, 0.05 mm layer thickness and XYZ build orientation. Optimized samples showed an 890% increase in elongation compared to neat ABS. Also, the impact strength of ABS samples showed a 60% improvement by adding 40 Wt.% SEBS. Originality/value The paper simultaneously evaluates the effects of material composition and 3D printing parameters (layer thickness, raster angle and build orientation) on the rheology, morphology, mechanical properties and surface roughness. Also, a mechanical properties comparison between printed samples and their compression-molded counterpart was conducted.

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