Manja Kitek Kuzman

Bio: Manja Kitek Kuzman is an academic researcher from University of Ljubljana. The author has contributed to research in topics: Sustainability & Wood flour. The author has an hindex of 13, co-authored 59 publications receiving 645 citations.

Effect of wood content in FDM filament on properties of 3D printed parts

Abstract: The effect of wood content in 3D printing materials on the properties of 3D printed parts was investigated. Six filaments using polylactic acid (PLA) with varying loading levels of wood particles from 0% to 50% by weight were produced and used for 3D printing. The density of the filaments and 3D printed parts used in this study slightly decreased with increasing wood content. The tensile strength of the filaments increased from 55 MPa to 57 MPa with an addition of 10% wood, but decreased with higher levels of wood content to 30 MPa for filaments with 50% wood content. The surface of the parts printed from the filament without the addition of wood was smoother and the printed part had no voids within the structure. With increasing wood content the surface becomes rougher, more voids were present, and had visible clusters of wood particles (due to wood particle clustering and clogging in the printer nozzle). Higher wood content in 3D printed parts decreased the storage modulus. measured with torsional loading on a rheometer, but did not change the glass transition temperature.

Effect of printing layer thickness on water absorption and mechanical properties of 3D-printed wood/PLA composite materials

Abstract: Effect of printing layer thickness on technological properties of 3D-printed specimens fabricated from wood flour/PLA filaments having a diameter of 1.75 mm was investigated. For this aim, four different printing layers, 0.05 mm, 0.1 mm, 0.2 mm, and 0.3 mm, were used in the production of the 3D-printed specimens. The water absorption of the specimens (28 days immersion in water) increased with increasing printing layer thickness while the thickness swelling decreased. The tensile and bending properties of the specimens significantly improved with decreasing printing layer thickness. The increase in the layer thickness caused bigger gaps, which increased the porosity in the cross section of the specimen. Higher porosity resulted in lower mechanical properties.

Comparison of some aggregation techniques using group analytic hierarchy process

Abstract: We presented and employed seven simple group AHP aggregation techniques.The LW-AHP model was a well evaluated group AHP method.For non-homogenous group we suggest to divide the group in smaller homogenous groups.One of our new group methods, the WGM-WAM or the WGM-LW-AHP can be employed. Group decision making is an important part of multiple criteria decision making and the analytic hierarchy process (AHP). The aim of this paper was to compare group AHP methods. Seven simple group AHP aggregation techniques that could be attractive for applications selected from the vast array of group AHP models proposed in the literature were selected for evaluation. We developed three new measures of evaluation: group Euclidean distance, group minimum violations, and distance between weights for the purpose of evaluation. The results of seven group AHP methods of the theoretical example were evaluated by three new evaluation measures, satisfactory index and fitting performance index. Furthermore, a case study of a decision making problem from the construction engineering field was performed and nine group AHP aggregation techniques, seven of them formerly presented and two new two stage group approaches were applied. Finally, the case study was evaluated using all five measures for each of the nine group decision making methods. The results showed that not all group AHP methods are equally convenient and that the selection of the method depended on the specific application.

Use of wood powder and adhesive as a mixture for 3D printing

Abstract: In recent years there has been much development in the field of additive manufacturing technologies, but only a few attempts have been made to use natural materials like wood for 3D printing. In this research different ratios of wood powder were used as a component in adhesive mixtures for 3D printing. Polyvinyl acetate and urea–formaldehyde adhesives were used as binders, and the optimum mixture was determined by measuring the corresponding extrusion forces. Simple blocks were 3D printed and the bending properties of these blocks were investigated. The bending strength depended on the amount of wood powder in the mixture and on the type of adhesive.

Materials and Design : The Art and Science of Material Selection in Product Design 2nd edition Ed. 2

Abstract: Materials are the stuff of design. From the very beginning of human history, materials have been taken from the natural world and shaped, modified, and adapted for everything from primitive tools to modern electronics. This renowned book by noted materials engineering author Mike Ashby and Industrial designer, Kara Johnson, explores the role of materials and materials processing in product design, with a particular emphasis on creating both desired aesthetics and functionality. The new edition will feature even more of the highly useful "materials profiles," that give critical design, processing, performance and applications criteria for each material in question. The reader will find information ranging from the generic and commercial names of each material, its physical and mechanical properties, its chemical properties, its common uses, how it is typically made and processed, and even its average price. And with improved photographs and drawings, the reader will be taken even more closely to the way real design is done by real designers, selecting the optimum materials for a successful product. * The best guide ever published on the on the role of materials, past and present, in product development, by noted materials authority Mike Ashby and professional designer Kara Johnson--now with even better photos and drawings on the Design Process * Significant new section on the use of re-cycled materials in products, and the importance of sustainable design for manufactured goods and services * Enhanced materials profiles, with addition of new materials types like nanomaterials, advanced plastics and bio-based materials

FDM 3D Printing of Polymers Containing Natural Fillers: A Review of their Mechanical Properties

Abstract: As biodegradable thermoplastics are more and more penetrating the market of filaments for fused deposition modeling (FDM) 3D printing, fillers in the form of natural fibers are convenient: They have the clear advantage of reducing cost, yet retaining the filament biodegradability characteristics. In plastics that are processed through standard techniques (e.g., extrusion or injection molding), natural fibers have a mild reinforcing function, improving stiffness and strength, it is thus interesting to evaluate whether the same holds true also in the case of FDM produced components. The results analyzed in this review show that the mechanical properties of the most common materials, i.e., acrylonitrile-butadiene-styrene (ABS) and PLA, do not benefit from biofillers, while other less widely used polymers, such as the polyolefins, are found to become more performant. Much research has been devoted to studying the effect of additive formulation and processing parameters on the mechanical properties of biofilled 3D printed specimens. The results look promising due to the relevant number of articles published in this field in the last few years. This notwithstanding, not all aspects have been explored and more could potentially be obtained through modifications of the usual FDM techniques and the devices that have been used so far.

The state of the art development of AHP (1979–2017): a literature review with a social network analysis

Abstract: Although many papers describe the evolution of the analytic hierarchy process (AHP), most adopt a subjective approach. This paper examines the pattern of development of the AHP research field using social network analysis and scientometrics, and identifies its intellectual structure. The objectives are: (i) to trace the pattern of development of AHP research; (ii) to identify the patterns of collaboration among authors; (iii) to identify the most important papers underpinning the development of AHP; and (iv) to discover recent areas of interest. We analyse two types of networks: social networks, that is, co-authorship networks, and cognitive mapping or the network of disciplines affected by AHP. Our analyses are based on 8441 papers published between 1979 and 2017, retrieved from the ISI Web of Science database. To provide a longitudinal perspective on the pattern of evolution of AHP, we analyse these two types of networks during the three periods 1979–1990, 1991–2001 and 2002–2017. We provide some basic statistics on AHP journals and researchers, review the main topics and applications of integrated AHPs and provide direction for future research by highlighting some open questions.

Bayesian best-worst method: A probabilistic group decision making model

Abstract: The best-worst method (BWM) is a multi-criteria decision-making method which finds the optimal weights of a set of criteria based on the preferences of only one decision-maker (DM) (or evaluator). However, it cannot amalgamate the preferences of multiple decision-makers/evaluators in the so-called group decision-making problem. A typical way of aggregating the preferences of multiple DMs is to use the average operator, e.g., arithmetic or geometric mean. However, averages are sensitive to outliers and provide restricted information regarding the overall preferences of all DMs. In this paper, a Bayesian BWM is introduced to find the aggregated final weights of criteria for a group of DMs at once. To this end, the BWM framework is meaningfully viewed from a probabilistic angle, and a Bayesian hierarchical model is tailored to compute the weights in the presence of a group of DMs. We further introduce a new ranking scheme for decision criteria, called credal ranking, where a confidence level is assigned to measure the extent to which a group of DMs prefers one criterion over one another. A weighted directed graph visualizes the credal ranking based on which the interrelation of criteria and confidences are merely understood. The numerical example validates the results obtained by the Bayesian BWM while it yields much more information in comparison to that of the original BWM.

Implementation of an Online Software Tool for the Analytic Hierarchy Process (AHP-OS)

Abstract: The Analytic Hierarchy Process (AHP) remains a popular multi-criteria decision method The author has implemented a free, web-based AHP online system with noteworthy features, allowing for the detailed analysis of decision problems Besides standard functions, like flexible decision hierarchies, support to improve inconsistent judgments, and alternative evaluation and sensitivity analysis, the software can handle group input, calculate group consensus based on Shannon ? and ?-entropy and estimate weight uncertainties based on randomized small variations of input judgments In addition, different AHP judgment scales can be applied a posteriori and alternative evaluation can be done using the weighted sum (WSM) or weighted product model (WPM) This flexibility opens up opportunities to study decision projects under various parameters The author’s intention was to provide a complete and free software tool for educational and research purposes where calculations and algorithms are well documented and all input data and results can be exported in an open format for further processing or presentation The article describes the basic concept and structure of the software and the underlying mathematical algorithms and methods Challenges and practical experiences during the implementation, validation and productive phase of the software are highlighted