Chad E. Duty, Vlastimil Kunc, Brett Compton, Brian Post, Donald Erdman, Rachel Smith, Randall Lind, Peter Lloyd and Lonnie Love
This paper aims to investigate the deposited structure and mechanical performance of printed materials obtained during initial development of the Big Area Additive Manufacturing…
Abstract
Purpose
This paper aims to investigate the deposited structure and mechanical performance of printed materials obtained during initial development of the Big Area Additive Manufacturing (BAAM) system at Oak Ridge National Laboratory. Issues unique to large-scale polymer deposition are identified and presented to reduce the learning curve for the development of similar systems.
Design/methodology/approach
Although the BAAM’s individual extruded bead is 10-20× larger (∼9 mm) than the typical small-scale systems, the overall characteristics of the deposited material are very similar. This study relates the structure of BAAM materials to the material composition, deposition parameters and resulting mechanical performance.
Findings
Materials investigated during initial trials are suitable for stiffness-limited applications. The strength of printed materials can be significantly reduced by voids and imperfect fusion between layers. Deposited material was found to have voids between adjacent beads and micro-porosity within a given bead. Failure generally occurs at interfaces between adjacent beads and successive layers, indicating imperfect contact area and polymer fusion.
Practical implications
The incorporation of second-phase reinforcement in printed materials can significantly improve stiffness but can result in notable anisotropy that needs to be accounted for in the design of BAAM-printed structures.
Originality/value
This initial evaluation of BAAM-deposited structures and mechanical performance will guide the current research effort for improving interlaminar strength and process control.
Details
Keywords
Josef Kunc, Vlastimil Reichel and Markéta Novotná
Effective management of shopping centres requires a good understanding of the consumers' behaviour and preferences as well as meeting the demand-side needs. The purpose of this…
Abstract
Purpose
Effective management of shopping centres requires a good understanding of the consumers' behaviour and preferences as well as meeting the demand-side needs. The purpose of this paper is to elucidate the factors affecting the frequency of shopping centres' visits, providing implications for shopping centre managers from the perspective of a Czech consumer.
Design/methodology/approach
The study was carried out in one of the Czech shopping centres in Brno due to its potentially standardisable common characteristics derived from the observation in the scatter plot. The standardized questionnaire survey on consumer shopping behaviour was conducted on a sample of more than 1,000 customers. The linear probability model and the logit model were applied to estimate impacts of included sociodemographic variables on the outcome.
Findings
The findings on the frequency of visits give an overview of the sociodemographic and spatial determinants increasing the visit regularity. From the managerial point of view, the importance of customers' activities and purposes is highlighted.
Practical implications
The implications can be provided to managers challenging to demand management and considering the investment projects. We come up with certain suggestions in terms of market segmentation, based on sociodemographic characteristics and shopping behaviour.
Originality/value
The paper provides insights into the preferences of the Czech consumers and extends the previous analysis of shopping behaviour by developing the statistical properties and demonstrating the variables and their influence on the frequency of visit.
Details
Keywords
Debashis Mishra and Anil Kumar Das
The purpose of the experimental investigation was to optimize the process parameters of the fused deposition modeling (FDM) technique. The optimization of the process was…
Abstract
Purpose
The purpose of the experimental investigation was to optimize the process parameters of the fused deposition modeling (FDM) technique. The optimization of the process was performed to identify the relationship between the chosen factors and the tensile strength of acrylonitrile butadiene styrene (ABS) and carbon fiber polylactic acid (PLA) thermoplastic material, FDM printed specimens. The relationship was demonstrated by using the linear experimental model analysis, and a prediction expression was established. The developed prediction expression can be used for the prediction of tensile strength of selected thermoplastic materials at a 95% confidence level.
Design/methodology/approach
The Taguchi L9 experimental methodology was used to plan the total number of experiments to be performed. The process parameters were chosen as three at three working levels. The working range of chosen factors was the printing speed (60, 80 and 100mm/min), 40%, 60% and 80% as the infill density and 0.1mm, 0.2mm and 0.3mm as the layer thickness. The fused deposition modeling process parameters were optimized to get the maximum tensile strength in FDM printed ABS and carbon fiber PLA thermoplastic material specimens.
Findings
The optimum condition was achieved by the process optimization, and the desired results were obtained. The maximum desirability was achieved as 0.98 (98%) for the factors, printing speed 100mm/min, infill density 60mm and layer thickness 0.3mm. The strength of the ABS specimen was predicted to be 23.83MPa. The observed strength value was 23.66MPa. The maximum desirability was obtained as 1 (100%) for the factors, printing speed 100mm/min, infill density 60mm and layer thickness 0.2mm. The strength of the carbon fiber PLA specimen was predicted to be 26.23MPa, and the obtained value was 26.49MPa.
Research limitations/implications
The research shows the useful process parameters and their suitable working conditions to print the tensile specimens of the ABS and carbon fiber PLA thermoplastics by using the fused deposition modeling technique. The process was optimized to identify the most influential factor, and the desired optimum condition was achieved at which the maximum tensile strength was reported. The produced prediction expression can be used to predict the tensile strength of ABS and carbon fiber PLA filaments.
Practical implications
The results obtained from the experimental investigation are useful to get an insight into the FDM process and working limits to print the parts by using the ABS and carbon fiber PLA material for various industrial and structural applications.
Social implications
The results will be useful in choosing the suitable thermoplastic filament for the various prototyping and structural applications. The products that require freedom in design and are difficult to produce by most of the conventional techniques can be produced at low cost and in less time by the fused deposition modeling technique.
Originality/value
The process optimization shows the practical exposures to state an optimum working condition to print the ABS and carbon fiber PLA tensile specimens by using the FDM technique. The carbon fiber PLA shows better strength than ABS thermoplastic material.