Johanna J. Schwartz, Joshua Hamel, Thomas Ekstrom, Leticia Ndagang and Andrew J. Boydston
Additive manufacturing (AM) methods such as material extrusion (ME) are becoming widely used by engineers, designers and hobbyists alike for a wide variety of applications…
Abstract
Purpose
Additive manufacturing (AM) methods such as material extrusion (ME) are becoming widely used by engineers, designers and hobbyists alike for a wide variety of applications. Successfully manufacturing objects using ME three-dimensional printers can often require numerous iterations to attain predictable performance because the exact mechanical behavior of parts fabricated via additive processes are difficult to predict. One of that factors that contributes to this difficulty is the wide variety of ME feed stock materials currently available in the marketplace. These build materials are often sold based on their base polymer material such as acrylonitrile butadiene styrene or polylactic acid (PLA), but are produced by numerous different commercial suppliers in a wide variety of colors using typically undisclosed additive feed stocks and base polymer formulations. This paper aims to present the results from an experimental study concerned with quantifying how these sources of polymer variability can affect the mechanical behavior of three-dimensional printed objects. Specifically, the set of experiments conducted in this study focused on following: several different colors of PLA filament from a single commercial supplier to explore the effect of color additives and three filaments of the same color but produced by three different suppliers to account for potential variations in polymer formulation.
Design/methodology/approach
A set of five common mechanical and material characterization tests were performed on 11 commercially available PLA filaments in an effort to gain insight into the variations in mechanical response that stem from variances in filament manufacturer, feed stock polymer, additives and processing. Three black PLA filaments were purchased from three different commercial suppliers to consider the variations introduced by use of different feed stock polymers and filament processing by different manufacturers. An additional eight PLA filaments in varying colors were purchased from one of the three suppliers to focus on how color additives lead to property variations. Some tests were performed on unprocessed filament samples, while others were performed on objects three-dimensional printed from the various filaments. This study looked specifically at four mechanical properties (Young’s modulus, storage modulus, yield strength and toughness) as a function of numerous material properties (e.g. additive loading, molecular weight, molecular weight dispersity, enthalpy of melting and crystallinity).
Findings
For the 11 filaments tested the following mean values and standard deviations were observed for the material properties considered: pa = 1.3 ± 0.9% (percent additives), Mw = 98.6 ± 16.4 kDa (molecular weight), Ð = 1.33 ± 0.1 (molecular weight dispersity), Hm = 37.4 ± 7.2 J/g (enthalpy of melting) and = 19.6 ± 2.1% (crystallinity). The corresponding mean values and standard deviations for the resulting mechanical behaviors were: E = 2,790 ± 145 MPa (Young’s modulus), E’ = 1,050 ± 125 MPa (storage modulus), Sy = 49.6 ± 4.93 MPa (yield strength) and Ut = 1.87 ± 0.354 MJ/m^3 (toughness). These variations were observed in filaments that were all manufactured from the same base polymer (e.g. PLA) and are only different in terms of the additives used by the manufacturers to produce different colors or different three-dimensional printing performance. Unfortunately, while the observed variations were significant, no definitive strong correlations were found between these observed variations in the mechanical behavior of the filaments studied and the considered material properties.
Research limitations/implications
These variations in mechanical behavior and material properties could not be ascribed to any specific factor, but rather show that the mechanical of three-dimensional printed parts are potentially affected by variations in base polymer properties, additive usage and filament processing choices in complex ways that can be difficult to predict.
Practical implications
These results emphasize the need to take processing and thereby even filament color, into account when using ME printers, they emphasize the need for designers to use AM with caution when the mechanical behavior of a printed part is critical and they highlight the need for continued research in this important area. While all filaments used were marked as PLA, the feedstock materials, additives and processing conditions created significant differences in the mechanical behavior of the printed objects evaluated, but these differences could not be accurately and reliably predicted as function of the observed material properties that were the focus of this study.
Originality/value
The testing methods used in the study can be used by engineers and creators alike to better analyze the material properties of their filament printed objects, to increase success in print and mechanical design. Furthermore, the results clearly show that as AM continues to evolve and grow as a manufacturing method, standardization of feedstock processing conditions and additives would enable more reliable and repeatable printed objects and would better assist designers in effectively implementing AM methods.
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Gregory I. Peterson, Mete Yurtoglu, Michael B Larsen, Stephen L. Craig, Mark A. Ganter, Duane W. Storti and Andrew J. Boydston
This paper aims to explore and demonstrate the ability to integrate entry-level additive manufacturing (AM) techniques with responsive polymers capable of mechanical to chemical…
Abstract
Purpose
This paper aims to explore and demonstrate the ability to integrate entry-level additive manufacturing (AM) techniques with responsive polymers capable of mechanical to chemical energy transduction. This integration signifies the merger of AM and smart materials.
Design/methodology/approach
Custom filaments were synthesized comprising covalently incorporated spiropyran moieties. The mechanical activation and chemical response of the spiropyran-containing filaments were demonstrated in materials that were produced via fused filament fabrication techniques.
Findings
Custom filaments were successfully produced and printed with complete preservation of the mechanochemical reactivity of the spiropyran units. These smart materials were demonstrated in two key constructs: a center-cracked test specimen and a mechanochromic force sensor. The mechanochromic nature of the filament enables (semi)quantitative assessment of peak loads based on color change, without requiring any external analytical techniques.
Originality/value
This paper describes the first examples of three-dimensional-printed mechanophores, which may be of significant interest to the AM community. The ability to control the chemical response to external mechanical forces, in combination with AM to process the bulk materials, potentiates customizability at the molecular and macroscopic length scales.
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Elizabeth A. Martin and Lynn A. Sheehan
Library buildings are routinely reimagined, remodeled, or built new to meet the changing needs of their community. The move from collection-centric to user-centric service models…
Abstract
Library buildings are routinely reimagined, remodeled, or built new to meet the changing needs of their community. The move from collection-centric to user-centric service models has generated numerous writings about the library as place and space. The one concept lacking in the scholarly discourse is the changing roles of librarians to meet the needs of these new spaces and places. How do librarians fit in the new equation? When addressing the professional identity of librarians, which aspect of their work will need to evolve and which will need to be let go? A critical facet of sustaining services in new spaces is the need to develop the sustainable librarian – to remove the stigma of the librarian as “jack of all trades, master of none.” In order to realize this new mindset of mastering our domain we need to begin reimagining our work. Some ways, this can be accomplished by writing increased flexibility into position descriptions and creating organizational structures to better support librarians within the new spaces. With these new developments to our professional identities, librarians may learn to employ entrepreneurial skills in order to continuously anticipate services and develop skill sets to aid the library’s ability to fulfill its purpose. The authors provide a literature review to discuss the changing role of the academic librarian to meet the evolution of the library building and services. We will provide an example through findings and practices of Grand Valley State University and how it reimagined roles in the early 2000s and continues to reimagine roles in a new building and a renovated branch library. The change of spaces and places in academic libraries to accommodate user needs and perceptions has impacted how academic librarians work in these spaces and places. Library administrators need to rethink workflows, and organizational charts by examining flexible workloads, cross-training initiatives, professional development around new skills, and the letting go of obsolete practices.
Originality/value – in this chapter, the authors will discuss how library leaders are charged with translating the new roles of their librarians to meet the needs of their community in these new spaces and how library leaders may look beyond the literature of the profession for ways to facilitate change.
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We live in the Age of Knowledge, which is impelling us towards the Age of Imagination. The technological wave rises and with it rises a wave of change that will affect both the…
Abstract
We live in the Age of Knowledge, which is impelling us towards the Age of Imagination. The technological wave rises and with it rises a wave of change that will affect both the economy and society. When these two waves will reach the coast where knowledge meets ignorance, and how to ride them, are questions that require us to imagine the future. We must, therefore, embark on the vessel of imagination, leaving behind us the baggage of what we know and understand. Imagination is not just the springboard for ideas; it also acts to connect ideas in different ways that may blossom in the garden of an entrepreneurial renaissance. Symbols, metaphors and concepts that belong to our tacit knowledge come to light in our memory. It is from here that the imagination draws its lifeblood, broadening our horizons, inducing us to interact with others who may be the bearers of other cultures. Are we ready to engage in an imaginative learning process to join business with innovation and art? Are we prepared to design a wide-open white space where the actors of entrepreneurship, innovation and art can generate a constructive tension that will sweep away what appears to be mutual antagonism or incompatibility?
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Tom Schultheiss, Lorraine Hartline, Jean Mandeberg, Pam Petrich and Sue Stern
The following classified, annotated list of titles is intended to provide reference librarians with a current checklist of new reference books, and is designed to supplement the…
Abstract
The following classified, annotated list of titles is intended to provide reference librarians with a current checklist of new reference books, and is designed to supplement the RSR review column, “Recent Reference Books,” by Frances Neel Cheney. “Reference Books in Print” includes all additional books received prior to the inclusion deadline established for this issue. Appearance in this column does not preclude a later review in RSR. Publishers are urged to send a copy of all new reference books directly to RSR as soon as published, for immediate listing in “Reference Books in Print.” Reference books with imprints older than two years will not be included (with the exception of current reprints or older books newly acquired for distribution by another publisher). The column shall also occasionally include library science or other library related publications of other than a reference character.
To be denied the status of formal worker is to be denied the rights and protections of the formal sector. Such classification is a source of insecurity and uncertainty for many…
Abstract
To be denied the status of formal worker is to be denied the rights and protections of the formal sector. Such classification is a source of insecurity and uncertainty for many. When employers privilege disembedded employment arrangements, workers in precarious semi-formal settings face many financial and relational challenges, yet receive limited support. In hostile economic, social, and legal contexts, what practices and discourses do these workers draw on to respond to their work situations? When, and against whom, do they struggle for labor embeddedness? Analyses of ethnographic and interview data from two fieldwork projects studying semi-formal work – one study of inmate labor in a US prison and one of a local independent culture industry – reveal that workers engage in collective and independent classification struggles in search of formal and symbolic reclassification. A typology of such struggles is presented. By viewing these practices through this lens, this chapter aims to reveal parallels in the experiences of workers in seemingly disconnected fields and advance our understanding of worker action and embeddedness in contemporary capitalism.
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Moore (1966) once argued that the American Civil War was a fundamentally “bourgeois” revolution. As such, Moore's account falls in line with much of the larger literature on…
Abstract
Moore (1966) once argued that the American Civil War was a fundamentally “bourgeois” revolution. As such, Moore's account falls in line with much of the larger literature on democratization, which emphasizes the class dimensions of democratic expansions and transitions, but is largely silent on how party politics are implicated in those processes. Such approaches miss a great deal of the party, inter-elite and discursive dynamics that are crucial to understanding the origins and consequences of democratic change. This chapter seeks to discern the impact of mass party formation and political discourse on modern routes to democracy through an examination of mid-19th-century Chicago politics. It holds to Moore's conclusion that the American Civil War was indeed a bourgeois revolution, while demonstrating that the trajectory of party politics before, during and after the war challenges Moore's interpretation of how class forces were mobilized in the American case. Partisan shifts, for example, worked at turns to weaken and strengthen the rhetorical and organizational basis of working-class mobilization, suggesting that democratization and the class coalitions that give rise to it are shaped and re-shaped by the context of partisan struggle.
Alan Lowe, Yesh Nama, Alice Bryer, Nihel Chabrak, Claire Dambrin, Ingrid Jeacle, Johnny Lind, Philippe Lorino, Keith Robson, Chiara Bottausci, Crawford Spence, Chris Carter and Ekaterina Svetlova
The purpose of this paper is to report the outcome of an interdisciplinary discussion on the concepts of profit and profitability and various ways in which we could potentially…
Abstract
Purpose
The purpose of this paper is to report the outcome of an interdisciplinary discussion on the concepts of profit and profitability and various ways in which we could potentially problematize these concepts. It is our hope that a much greater attention or reconsideration of the problematization of profit and related accounting numbers will be fostered in part by the exchanges we include here.
Design/methodology/approach
This paper adopts an interdisciplinary discussion approach and brings into conversation ideas and views of several scholars on problematizing profit and profitability in various contexts and explores potential implications of such problematization.
Findings
Profit and profitability measures make invisible the collective endeavour of people who work hard (backstage) to achieve a desired profit level for a division and/or an organization. Profit tends to preclude the social process of debate around contradictions among the ends and means of collective activity. An inherent message that we can discern from our contributors is the typical failure of managers to appreciate the value of critical theory and interpretive research for them. Practitioners and positivist researchers seem to be so influenced by neo-liberal economic ideas that organizations are distrusted and at times reviled in their attachment to profit.
Research limitations/implications
Problematizing opens-up the potential for interesting and significant theoretical insights. A much greater pragmatic and theoretical reconsideration of profit and profitability will be fostered by the exchanges we include here.
Originality/value
In setting out a future research agenda, this paper fosters theoretical and methodological pluralism in the research community focussing on problematizing profit and profitability in various settings. The discussion perspectives offered in this paper provides not only a basis for further research in this critical area of discourse and regulation on the role and status of profit and profitability but also emancipatory potential for practitioners (to be reflective of their practices and their undesired consequences of such practices) whose overarching focus is on these accounting numbers.
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Trista Hollweck, Deborah M. Netolicky and Paul Campbell
The aim of this paper is to define pracademia and conceptualise it in relation to educational contexts. This paper contributes to and stimulates a continuing and evolving…
Abstract
Purpose
The aim of this paper is to define pracademia and conceptualise it in relation to educational contexts. This paper contributes to and stimulates a continuing and evolving conversation around pracademia and its relevance, role and possibilities.
Design/methodology/approach
This paper is a conceptual exploration. It draws upon existing and emerging pieces of literature, the use of metaphor as a meaning-making tool, and the positionalities of the authors, to develop the concept of pracademia.
Findings
The authors posit that pracademics who simultaneously straddle the worlds of practice, policy, and academia embody new possibilities as boundary spanners in the field of education for knowledge mobilization, networks, community membership, and responding to systemic challenges. However, being a pracademic requires the constant reconciling of the demands of multi-membership and ultimately, pracademics must establish sufficient legitimacy to be respected in two or more currently distinct worlds.
Practical implications
This paper has implications for knowledge mobilization, networks, boundary spanners, leadership, professional learning, and connecting practice, policy, and research. While the authors are in the field of education, this exploration of pracademia is relevant not only to the field of education but also to other fields in which there is a clear need to connect practice/policy with scholarship.
Originality/value
This paper provides a new definition of pracademia and argues that pracademia identifies an important yet relatively unknown space with many possibilities in the field of education.