Tino Stanković

A Generalized Optimality Criteria Method for Optimization of Additively Manufactured Multimaterial Lattice Structures

Recent progress in Additive Manufacturing (AM) allows for printing customized products with multiple materials and complex geometries that could form the basis of multi-material designs with high performance and novel functions. Effectively designing such complex products for optimal performance within the confines of additive manufacturing constraints is challenging due to the need to consider fabrication constraints while searching for optimal designs with a large number of variables, which stem from new AM capabilities. In this study, fabrication constraints are addressed through empirically characterizing multiple printed materials’ Young’s modulus and density using a multi-material inkjet-based 3D-printer. Data curves are modeled for the empirical data describing two base printing materials and twelve mixtures of them as inputs for a computational optimization process. An optimality criteria method is developed to search for solutions of multi-material lattices with fixed topology and truss cross-section sizes. Two representative optimization studies are presented and demonstrate higher performance with multi-material approaches in comparison to using a single material. These include the optimization of a cubic lattice structure that must adhere to a fixed displacement constraint and a compliant beam lattice structure that must meet multiple fixed displacement constraints. Results demonstrate the feasibility of the approach as a general synthesis and optimization method for multi-material, lightweight lattice structures that are large-scale and manufacturable on a commercial AM printer directly from the design optimization results.

Visualisation of the organisation knowledge structure evolution

Purpose – The paper aims to provide a methodology by which organisational knowledge can be extracted and visualised dynamically over time, providing a glimpse into the knowledge evolution processes that occur within organisations. Design/methodology/approach – Recursive analysis of email interactions is offered as a case to account for the knowledge structure evolution related to the different programs of international non-governmental organization (INGO). Several methods are used: analysis of the network expansion to see whether the process is random or uniform is performed, visualisation of the network configuration changes throughout studied time period; and the statistical examination of network formation. Findings – The results of the presented study indicate that content structure of electronic knowledge networks exhibits hierarchical and centralised tendencies. The social network analysis results suggest that INGO exhibits non-hierarchical and decentralized structure of the individuals contributing to the discussion lists. Research limitations/implications – By providing the means to carry out network evolution analysis of content structure dynamics and social interactions, the presented work provides a means for probabilistically modelling patterns of organisational knowledge evolution. Practical implications – The approach allows the exploration of the dynamics of tacit to explicit knowledge, from individual to the group and from informal groups to the whole organisation. Originality/value – By displaying the large collection of the key phrases that reflected the evolution of the organisational knowledge structure over the time, organisational emails are placed in meaningful context explaining the language of the organisation and context of knowledge structure evolution.

Optimization of Additively Manufactured Multi-Material Lattice Structures Using Generalized Optimality Criteria

Recent progress in additive manufacturing allows for printing customized products with multiple materials and complex geometries. Effectively designing such complex products for optimal performance within the confines of additive manufacturing constraints is challenging, due to the large number of variables in the search space and uncertainties about how the manufacturing processes affect fabricated materials and structures. In this study, characteristics of materials, i.e. Young’s modulus (E), ultimate tensile strength (UTS) and density (ρ), for a multi-material inkjet-based 3D-printer are measured experimentally in order to generate data curves for a computational optimization process in configuring multimaterial lattice structures. An optimality criteria method is developed for computationally searching for optimal solutions of a multi-material lattice with fixed topology and truss cross-section sizes using the empirically obtained material measurements. Results demonstrate the feasibility of the approach for optimizing multi-material, lightweight truss structures subject to displacement constraints.Copyright

Grammatical Evolution of Technical Processes

The aim of this thesis is to provide a support to the beginning of the conceptual development phase by offering designers the possibility to computationally synthesise technical processes in order to obtain operand transformation variants in the respect to known technological principles. To accomplish the aim the following objectives had to be met: a theoretical objective which considered the development of a method for generation of operand transformation variants; and an empirical objective as the implementation of the method as a computational tool built to a stage that allows verification of the research results. First, it was necessary to understand the phenomenon of problem solving and cognitive aspects of synthesis as a part of the problem solving activity. Then, the state-of-the-art review on the Computational Design Synthesis (CDS) [2] was conducted the purpose of which was the determination of theoretical and methodological background of the current research projects and the comparison and the systematization of those in order to focus this research. The efforts where turned to the exploration of the existent mathematical concepts which could be used for the modelling of technical processes and related synthesis method. Based on the findings from the field of CDS it was concluded to conceive the method as a knowledgebased with the solution emerging as a result of successive application of production rules in which the knowledge about technical processes and working principles is formalised. The theoretical objective concluded with the main scientific contribution of this thesis: (1) the creation of multigraph based formal model of technical process, (2) the definition of graphgrammar based formal model of technical process synthesis, (3) addition of stochastic search to technical process synthesis by applying grammatical evolution [3]. Within the empirical objective a computational tool was realised on the foundations of the developed method. During the research it was found that knowledge about technical processes still does not exists in the accessible open taxonomies or ontologies as per se, which required to propose (4) knowledge formalisation suggestions when defining the graph grammar of technical processes.

Formal modelling of technical processes and technical process synthesis

The computational design synthesis approach considered in this paper, proposes directed multigraph and graph grammar-based models of technical processes and technical process synthesis. The theory of technical systems, which is adopted as a theoretical foundation for this work, assumes a teleological viewpoint bringing together the purpose of technical systems and fulfilment of customer demands and societal needs. These demands and needs are met by means of a technical process inside which the operands are transformed with the assistance of a technical system to achieve a desired state. Formal models of technical processes and technical process synthesis establish the foundation for further application of search algorithms to support early engineering design. The engineering knowledge about technical processes is provided within a set of graph grammar rules. As the result of the proposed approach, the designer is enabled to consider different operand transformations in an expedient fashion with the possibility of the generation of novel alternatives. The proposed approach is illustrated through an example of the design of a stiffened panel assembly line involving welding and riveting as two basic principles.

Experimental design research : Approaches, perspectives, applications

This book presents a new, multidisciplinary perspective on and paradigm for integrative experimental design research. It addresses various perspectives on methods, analysis and overall research app ...

Task categorisation for identification of design automation opportunities

ABSTRACT Engineering design automation has been an active field of research and application for more than five decades. Despite a multitude of available methods stemming from research fields such as Knowledge-Based Engineering (KBE) and Computational Design Synthesis (CDS) the application context in industry is mostly limited to routine tasks. Here we propose a means to foster the transition of academic methods to industrial practice through a comprehensible and comprehensive design automation task categorisation that allows practitioners to grasp the opportunities state-of-the-art design automation offers. The categorisation is based on a critical investigation of 77 papers stemming from KBE and CDS, respectively, and is detailed with respect to knowledge needed for complete formalisation of a task, i.e. inputs, outputs and goals, as well as available automation methods. A thorough discussion indicates the context of the work with current design practice and provides a consolidation of the research fields KBE and CDS including the derivation of technological requirements for design automation task definition by practitioners. Thus, this paper contributes not only by consolidating two research fields but also by presenting technological requirements for further streamlining the process of realising design automation applications in industry.

An Introduction to Experimental Design Research

Design research brings together influences from the whole gamut of social, psychological, and more technical sciences to create a tradition of empirical study stretching back over 50 years (Horvath 2004; Cross 2007). A growing part of this empirical tradition is experimental, which has gained in importance as the field has matured. As in other evolving disciplines, e.g. behavioural psychology, this maturation brings with it ever-greater scientific and methodological demands (Reiser 1939; Dorst 2008). In particular, the experimental paradigm holds distinct and significant challenges for the modern design researcher. Thus, this book brings together leading researchers from across design research in order to provide the reader with a foundation in experimental design research; an appreciation of possible experimental perspectives; and insight into how experiments can be used to build robust and significant scientific knowledge. This chapter sets the stage for these discussions by introducing experimental design research, outlining the various types of experimental approach, and explaining the role of this book in the wider methodological context.

Tracing Engineering Evolution with Evolutionary Algorithms

The investigations of the recent complex engineering knowledge, experience, analytical and computational tools may serve to explain the technical progress and facilitate the future development. For this purpose this chapter will present how the evolutionary algorithms can simulate the developing complexity of engineering reasoning that in reverse can back-trace the primitive origins of modern technical products. The chapter will resume the evolutionary algorithms as well as the evolutionary optimization and design processes based on innovative and creative activities with the aim to define their potentialities in discovering the evolution of engineering products.

An Analysis of Engineers Information Seeking Activity

Information seeking is an important part of the engineering design process. In this context the Internet has become a significant source of information, shaping the way engineers work and interact. Current work has focused on characterizing this activity in terms of total time allocated to different information sources or overall tasks, such as evaluating. However, these approaches do not give an understanding of how engineers information seeking affects their problem solving activity and ultimately their performance in the context of the design process. As such, a new approach is needed to decompose the complexity of information seeking activity in order to more effectively support the evolving needs of engineering designers and design researchers. This paper addresses these issues by using an experimental study and network visualization technique to analyze Internet based information seeking activity and its affect on engineers overall performance during the information seeking/feasibility stage of the design process. The study uses both final year trainee engineers and practicing engineers in order to more fully explore the different modes of information seeking activity. With the study complete, the visual network analysis is used to explore patterns of information seeking and other design activity. Based on the results, three clearly differentiated types of information seeking activity are identified and discussed.Copyright