Supportless printing of lattice structures by metal fused filament fabrication (MF3) of Ti-6Al-4V: design and analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Qasim Shaikh ◽  
Serena Graziosi ◽  
Sundar Vedanarayan Atre
Keyword(s):  
Relative Density ◽  
Mechanical Performance ◽  
Unit Cell ◽  
Lattice Structures ◽  
Fused Filament Fabrication ◽  
Cross Sectional ◽  
Content Type ◽  
Aspect Ratios ◽  
Lattice Geometry ◽  
Starting Point

Purpose This paper aims to investigate the feasibility of supportless printing of lattice structures by metal fused filament fabrication (MF3) of Ti-6Al-4V. Additionally, an empirical method was presented for the estimation of extrudate deflection in unsupported regions of lattice cells for different geometric configurations. Design/methodology/approach Metal-polymer feedstock with a solids-loading of 59 Vol.% compounded and extruded into a filament was used for three-dimensional printing of lattice structures. A unit cell was used as a starting point, which was then extended to multi-stacked lattice structures. Feasible MF3 processing conditions were identified to fabricate defect-free lattice structures. The effects of lattice geometry parameters on part deflection and relative density were investigated at the unit cell level. Computational simulations were used to predict the part quality and results were verified by experimental printing. Finally, using the identified processing and geometry parameters, multi-stacked lattice structures were successfully printed and sintered. Findings Lattice geometry required considerable changes in MF3 printing parameters as compared to printing bulk parts. Lattice cell dimensions showed a considerable effect on dimensional variations and relative density due to varying aspect ratios. The experimental printing of lattice showed large deflection/sagging in unsupported regions due to gravity, whereas simulation was unable to estimate such deflection. Hence, an analytical model was presented to estimate extrudate deflections and verified with experimental results. Lack of diffusion between beads was observed in the bottom facing surface of unsupported geometry of sintered unit cells as an effect of extrudate sagging in the green part stage. This study proves that MF3 can fabricate fully dense Ti-6Al-4V lattice structures that appear to be a promising candidate for applications where mechanical performance, light-weighting and design customization are required. Originality/value Supportless printing of lattice structures having tiny cross-sectional areas and unsupported geometries is highly challenging for an extrusion-based additive manufacturing (AM) process. This study investigated the AM of Ti-6Al-4V supportless lattice structures using the MF3 process for the first time.

The emergence of entrepreneurial team as a research field – way forward

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Willy Das ◽  
Satyasiba Das ◽  
Manojit Chattopadhyay
Keyword(s):  
Research Agenda ◽  
Research Field ◽  
Academic Disciplines ◽  
Future Research ◽  
Cross Sectional ◽  
Content Type ◽  
Future Research Agenda ◽  
Starting Point ◽  
Entrepreneurial Team ◽  
Research Stream

PurposeThe purpose of this paper is to review and critique the existing literature on entrepreneurial teams (ET) by taking a multi-disciplinary viewpoint and provide a future research agenda based on the identified themes and trends.Design/methodology/approachA systematic literature review (SLR) was undertaken using “business source complete”. Further scrutiny and application of exclusion criteria led to a final sample consisting of 139 papers from 27 different journals belonging to not just entrepreneurship and strategic management but also other disciplines like OB, finance, sociology, psychology, etc. Using qualitative thematic analysis, the authors identified 11 major themes.FindingsThe paper reviews both the eleven themes and the linkages between the themes. Thereby identifying areas that have been understudied and those that have received comparatively more attention. The review revealed that the research stream possesses certain conceptual and methodological concerns apart from its cross-sectional and primarily bivariate nature. Five such main concerns have been identified and discussed in detail. Other elements of the resulting research agenda include calls for more clinical process-oriented research, further attention to context, shifting the level of analysis, and a need to integrate across disciplines.Originality/valueThis paper incorporates a broad insight of ET across academic disciplines to show how future contributions could benefit by incorporating research from other fields. In doing so, provides a starting point for more nuanced discussions around the interrelationships between the different conversations that are taking place in the ET literature.

Peer-to-peer word-of-mouth: word-of-mouth extended to group online exchange

2018 ◽  
Vol 42 (2) ◽  
pp. 176-190 ◽  
Author(s):  
Anat Toder-Alon ◽  
Frédéric F. Brunel
Keyword(s):  
Online Community ◽  
Word Of Mouth ◽  
Peer To Peer ◽  
Bulletin Board ◽  
Cross Sectional ◽  
Content Type ◽  
Social And Emotional ◽  
Starting Point ◽  
Online Exchange ◽  
New Perspective

Purpose The purpose of this paper is to investigate how peer-to-peer word-of-mouth (PPWOM) conversations evolve over time because of the dynamic social nature of the community in which they take place. Design/methodology/approach This study analyzed PPWOM conversations in an online community website for new and expectant mothers. Two data collection phases were undertaken during a four-year period. In phase I, messages were collected for a one-month period from five different bulletin boards (i.e. cross-sectional data) and at two points in time (i.e. semi-longitudinal). In phase II, a full longitudinal study was conducted, and the complete text of all messages of a newly formed bulletin board was captured for a nine-month period. The corpus of messages was examined in line with the basic tools of ethnomethodology and conversation analysis. Findings This research developed a typology of PPWOM genres and showed that these genres change over the community lifespan. The findings confirmed that the levels of social cohesiveness and the interaction communicative motives are the main factors that distinguish different PPWOM genres. Research limitations/implications This research has offered a new perspective into the study of PPWOM, and hopefully it will serve as a starting point for a broader dialogue regarding the social context in which PPWOM is exchanged. Originality/value In contrast to traditional word-of-mouth research, this study demonstrated that PPWOM conversations go much beyond the exchange of functional information, and instead serve numerous social and emotional goals.

Finite element analysis of gradient lattice structure patterns for bone implant design

2020 ◽  
Vol 11 (4) ◽  
pp. 535-545
Author(s):  
Asliah Seharing ◽  
Abdul Hadi Azman ◽  
Shahrum Abdullah
Keyword(s):  
Finite Element Analysis ◽  
Relative Density ◽  
Mechanical Behaviour ◽  
Lattice Structure ◽  
Lattice Structures ◽  
Element Analysis ◽  
Bone Implant ◽  
Content Type ◽  
Octet Truss ◽  
Structure Patterns

PurposeThe objective of this paper is to identify suitable lattice structure patterns for the design of porous bone implants manufactured using additive manufacturing.Design/methodology/approachThe study serves to compare and analyse the mechanical behaviours between cubic and octet-truss gradient lattice structures. The method used was uniaxial compression simulations using finite element analysis to identify the translational displacements.FindingsFrom the simulation results, in comparison to the cubic lattice structure, the octet-truss lattice structure showed a significant difference in mechanical behaviour. In the same design space, the translational displacement for both lattice structures increased as the relative density decreased. Apart from the relative density, the microarchitecture of the lattice structure also influenced the mechanical behaviour of the gradient lattice structure.Research limitations/implicationsGradient lattice structures are suitable for bone implant applications because of the variation of pore sizes that mimic the natural bone structures. The complex geometry that gradient lattice structures possess can be manufactured using additive manufacturing technology.Originality/valueThe results demonstrated that the cubic gradient lattice structure has the best mechanical behaviour for bone implants with appropriate relative density and pore size.

On the nomological net of (non-)workaholic subtypes

2019 ◽  
Vol 24 (7) ◽  
pp. 672-685
Author(s):  
Greta Ontrup ◽  
Justine Patrzek
Keyword(s):  
Latent Profile Analysis ◽  
Profile Analysis ◽  
Statistical Technique ◽  
Online Questionnaire ◽  
Cross Sectional ◽  
Content Type ◽  
Future Studies ◽  
Model Based Clustering ◽  
Starting Point ◽  
Cross Sectional Design

Purpose Research on workaholism distinguishes between enthusiastic and non-enthusiastic workaholics, a typology used in many studies. Yet, the methodical foundation on which the derivation of the types is based lacks robust statistical evidence. The purpose of this paper is twofold: first, to replicate the often-cited typology of enthusiastic and non-enthusiastic workaholics (and non-workaholic subtypes), based on model-based clustering as a robust statistical technique; and second, to validate the class solution based on affective, cognitive and behavioral measures. Design/methodology/approach The study followed a cross-sectional design, targeting a sample of people from various fields of industries. An online questionnaire was distributed; workaholism was assessed with McMillan et al.’s (2002) Work-BAT-R scales. A total of 537 respondents’ data were analyzed. Findings Latent profile analysis extracted four classes, namely, enthusiastic and non-enthusiastic workaholics and relaxed and uninvolved non-workaholics. As expected, workers characterized by high enjoyment (enthusiasts and relaxed) showed higher job satisfaction and occupational self-efficacy than workers with low enjoyment (non-enthusiasts and uninvolved). Relaxed workers reported higher life satisfaction than all other classes. Originality/value The robust methodology applied establishes a good starting point for future studies investigating workers subtypes: the replication suggests that the workaholic subtypes might be core profiles that occur in different populations with regularity. As a next step, the replication of the typology based on alternative operationalizations of workaholism is proposed for future studies.

On the use of high viscosity polymers in the fused filament fabrication process

2017 ◽  
Vol 23 (4) ◽  
pp. 727-735 ◽  
Author(s):  
Muhammad Hussam Khaliq ◽  
Rui Gomes ◽  
Célio Fernandes ◽  
João Nóbrega ◽  
Olga Sousa Carneiro ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
High Viscosity ◽  
Polymer Processing ◽  
General Purpose ◽  
Good Choice ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Performance Requirements ◽  
Functional Prototype ◽  
The One

Purpose This work aims to provide additional insights regarding the practicability of using conventional materials in the fused filament fabrication (FFF) process. Design/methodology/approach Two different acrylonitryle butadiene styrene (ABS) grades are studied and compared, aiming to check to what extent the regular ABS developed for conventional polymer processing, with a different rheology than the one provided for the FFF process, can also be used in this process (FFF). Findings The rheological results show that a general-purpose ABS (ABS-GP) melt is much more viscous and elastic than ABS-FFF. It is clear that using ABS-GP as feedstock material in the FFF process results in poor coalescence and adhesion between the extruded filaments, which has a detrimental effect on the mechanical properties of the printed specimens. Despite its lower performance, ABS-GP can be a good choice if the objective is to produce an aesthetical prototype. If the objective is to produce a functional prototype or a final part, its mechanical performance requirements will dictate the choice. Originality/value This work provides insightful information regarding the use of high viscosity materials on the 3D printing process.

scholarly journals Variations in involvement: motivating bystanders to care for senior citizens

2017 ◽  
Vol 11 (2) ◽  
pp. 117-132 ◽  
Author(s):  
Sarah Keller ◽  
Timothy Wilkinson
Keyword(s):  
Mail Survey ◽  
The Elderly ◽  
Health Issues ◽  
Cross Sectional ◽  
Perceived Susceptibility ◽  
Content Type ◽  
Care Services ◽  
Starting Point ◽  
Survey Responses ◽  
The Impact

Purpose The purpose of this study is to determine the impact of a senior service advertising campaign designed to increase volunteerism and financial donations among bystanders. Design/methodology/approach A cross-sectional mail survey was administered to 2,500 adults; 384 usable responses were obtained. Survey responses were analyzed by level of exposure and involvement in senior care. Findings High-involvement individuals viewed the ads more favorably and exhibited stronger senior caretaking intentions. Low-involvement consumers were less likely to see their own potential contributions to senior care services as effective. Research limitations/implications Characterizing involvement in terms of awareness, awareness involvement, perceived severity and perceived susceptibility, provides a starting point for future examinations of the relationship between involvement, perceived efficacy and various forms of promotion. Practical implications From a practitioner’s standpoint, this study identifies specific features of campaign design and audience profiling that might increase the effectiveness of bystander interventions. This study offers not only constructs that can be used for identifying particular audience subsets but also illustrates the practical ways in which perceived susceptibility and perceived response efficacy to a given issue can be addressed through a mass media campaign. Social implications Snowballing healthcare costs coupled with an avalanche of baby boomers entering the elderly phase of the life cycle make the need for bystander involvement in the lives of seniors increasingly important. Originality/value With limited theoretical and practical guidance on how to motivate bystanders to engage in prosocial behaviors, health communicators and marketers are challenged to address a vast range of public health issues that require citizen engagement. The research reviewed and presented here indicates the hope for engaging the public to become active players in making the nation a safer and healthier place.

Combining FEM and MD to simulate C60/PA-12 nanocomposites

2019 ◽  
Vol 10 (3) ◽  
pp. 380-392
Author(s):  
Georgios I. Giannopoulos ◽  
Stelios K. Georgantzinos ◽  
Androniki Tsiamaki ◽  
Nicolaos Anifantis
Keyword(s):  
Mechanical Behaviour ◽  
Numerical Scheme ◽  
Mechanical Performance ◽  
Numerical Technique ◽  
Computational Cost ◽  
Md Simulations ◽  
Unit Cell ◽  
Content Type ◽  
Polyamide 12 ◽  
Solid Element

Purpose The purpose of this paper is the computation of the elastic mechanical behaviour of the fullerene C60 reinforced polyamide-12 (PA-12) via a two-stage numerical technique which combines the molecular dynamics (MD) method and the finite element method (FEM). Design/methodology/approach At the first stage, the proposed numerical scheme utilizes MD to characterize the pure PA-12 as well as a very small cubic unit cell containing a C60 molecule, centrally positioned and surrounded by PA-12 molecular chains. At the second stage, a classical continuum mechanics (CM) analysis based on the FEM is adopted to approximate the elastic mechanical performance of the nanocomposite with significantly lower C60 mass concentrations. According to the computed elastic properties arisen by the MD simulations, an equivalent solid element with the same size as the unit cell is developed. Then, a CM micromechanical representative volume element (RVE) of the C60 reinforced PA-12 is modelled via FEM. The matrix phase of the RVE is discretized by using solid finite elements which represent the PA-12 mechanical behaviour predicted by MD, while the C60 neighbouring location is meshed with the equivalent solid element. Findings Several multiscale simulations are performed to study the effect of the nanofiller mass fraction on the mechanical properties of the C60 reinforced PA-12 composite. Comparisons with other corresponding experimental results are attempted, where possible, to test the performance of the proposed method. Originality/value The proposed numerical scheme allows accurate representation of atomistic interfacial effects between C60 and PA-12 and simultaneously offers a significantly lower computational cost compared with the MD-only method.

Logistics service quality: where we are and where we go in the context of airline industry

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Peeraya Thongkruer ◽  
Sawat Wanarat
Keyword(s):  
Service Quality ◽  
Value Chain ◽  
Airline Industry ◽  
Future Research ◽  
Cross Sectional ◽  
Content Type ◽  
Logistics Service ◽  
Marketing Function ◽  
Starting Point ◽  
Logistics Service Quality

Purpose In practice and in literature, logistics service quality is one of the key concepts in any service industry, including airlines. However, the breadth of content and the inconsistent accounts make comprehensive understanding of service quality elusive, thereby necessitating the conduct of a systematic review of the literature on service quality in the context of airlines. In doing so, this study aims to provide a clear, consistent and current overview of the literature, enabling the advancement of theory and research in service quality. Design/methodology/approach In particular, this study presents several aspects of logistics service quality based on the 52 articles reviewed published between 1993 and 2019. Content analysis was used to analyze the data in terms of key attributes of service quality from the selected articles. Findings Following an analysis, this study summarizes the antecedents and consequences, along with mediators and moderators, and develops a review framework of service quality. Research limitations/implications This study provides a starting point for understanding logistics service quality in a context of airline where choice of perspective (at three different perspectives) and framing of context (where logistics interfaces with marketing function, thereby ensuring a well-functiong synthesis of marketing and service activities in the value chain) are of decisive importance. It also expands an understanding of service quality in marketing field with an integration of logistics function as well as challenging some of the conventional knowledge of the applying logistics in service-based business like the airlines. However, this paper is restricted by several limitations that must be taken into account when applying its findings such as context-specific results,cross-sectional data and recall variables. Originality/value This paper provides a clear and consistent concept, as well as a current overview of the literature, which enables advancement in theory and research. It also reveals theoretical underpinnings of the research stream and outlines future research directions. Additionally, it challenges some of the conventional knowledge of the applying logistics on service-based business such as airline which broadens the scope of our thinking and provides a foundation for future study.

From value-based human resource practices to i-deals: software companies in Vietnam

2015 ◽  
Vol 44 (1) ◽  
pp. 39-68 ◽  
Author(s):  
Tuan Trong Luu ◽  
Chris Rowley
Keyword(s):  
Human Resource ◽  
Structural Equation ◽  
Driving Forces ◽  
Equation Modeling ◽  
Cross Sectional ◽  
Upward Influence ◽  
Content Type ◽  
Hr Practices ◽  
Software Companies ◽  
Starting Point

Purpose – Idiosyncratic deals (i-deals) are employees’ proactive individualized negotiations with their employer for higher job autonomy corresponding to their competencies and values. The path to i-deals in the organization can commence with value-based human resource (HR) practices. The purpose of this paper is to investigate this path from value-based HR practices to i-deals through the mediating roles of corporate social responsibility (CSR), emotional intelligence (EI) and upward influence behaviors. Design/methodology/approach – The hypothesized model was verified through the structural equation modeling-based analysis of cross-sectional data from 362 respondents from Vietnam-based software companies. Findings – Research findings found value-based HR practices as the starting point of the path to i-deals, in which consecutive crucial milestones are ethical CSR, EI and organizationally beneficial upward influence behaviors. Originality/value – I-deals literature, through this empirical inquiry, is further extended by discovering the socialized driving forces, such as CSR and EI, behind individualized i-deals.

Tensile strength of partially filled FFF printed parts: meta modelling

2017 ◽  
Vol 23 (3) ◽  
pp. 524-533 ◽  
Author(s):  
Shahrain Mahmood ◽  
A.J. Qureshi ◽  
Kheng Lim Goh ◽  
Didier Talamona
Keyword(s):  
Mathematical Model ◽  
Tensile Strength ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Fused Filament Fabrication ◽  
Cross Sectional ◽  
Content Type ◽  
Test Pieces ◽  
Solid Part ◽  
The Cross

Purpose This paper aims to investigate the tensile strength of partially filled fused filament fabrication (FFF) printed parts with respect of cross-sectional geometry of partially filled test pieces. It was reported in the authors’ earlier work that the ultimate tensile strength (UTS) is inversely proportional to the cross-sectional area of a specimen, whereas the number of shells and infill density are directly proportional to the UTS with all other parameters being held constant. Here, the authors present an in-depth evaluation of the phenomenon and a parametric model that can provide useful estimates of the UTS of the printed part by accounting for the dimensions of the solid floor/roof layers, shells and infills. Design/methodology/approach It was found that partially filled FFF printed parts consist of hollow sections. Because of these voids, the conventional method of determining the UTS via the gross cross-sectional area given by A = b × h, where b and h are the width and thickness of the printed part, respectively, cannot be used. A mathematical model of a more accurate representation of the cross-sectional area of a partially filled part was formulated. Additionally, the model was extended to predict the dimensions as well as the lateral distortion of the respective features within a printed part using input values from the experimental data. Findings The result from this investigation shows that to calculate the UTS of a partially filled FFF part, the calculation based on the conventional approach is not sufficient. A new meta-model is proposed which takes into account the geometry of the internal features to give an estimate of the strength of a partially filled printed part that is closer to the value of the strength of the material that is used for fabricating the part. Originality/value This paper investigates the tensile strength of a partially filled FFF printed part. The results have shown that the tensile strength of a partially filled part can be similar to that of a solid part, at a lower cost: shorter printing time and lower material usage. By taking into account the geometries within a printed part, the cross-sectional area can be accurately represented. The mathematical model which was developed would aid end-users to predict the tensile strength for a given set of input values of the process parameters.

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