http://hdl.handle.net/2005/29 2013-05-05T13:09:29Z http://hdl.handle.net/2005/1328 Title: An Interactive Support For Developing Environmentally Friendly Product Lifecycles Authors: Kota, Srinivas Abstract: Products make substantial impact on environment. Design for Environment (DfE) is an approach to design where all the environmental impacts of a product are considered over entire products life. Since over 80% of the product costs are committed during the early stages, design can play a central role in reducing this environmental overloading by product. However, unlike cost and performance, use of environmental criteria and DfE is far from part of mainstream designing. Individual guidelines often exist for DfE but these are not integrated with design tools. There is a need for capture of the rationale in design process as a know how backup for later use. Life Cycle Assessment (LCA) is currently the most promising and scientifically proven technique for estimating environmental impacts of a product during its lifecycle. Current LCA tools are not well integrated with design process and CAD tools. Consequently, there is a need for an LCA tool integrated into the natural design process that can be applied to early as well as detailed design stages. Detailed LCA is critically dependent on high volumes of product specific data, time consuming, often unaffordable and used after the detailed stages of design. Current approximate LCA methods are either incomplete, inaccurate or require prior knowledge of what data is important There is substantial uncertainty involved in the environmental impact calculations in LC. While Literature discusses uncertainty of impact data, there is no discussion on how to calculate and represent the total uncertainty in the potential impact of a product proposal at any given stage in design with respect to LCA. There is a need for a method that can aid in decision making by supporting quantitative comparison of available alternatives to identify the best alternative, under uncertain information about alternatives. Often the likely performance, cost or environmental impacts of a product proposal could be estimated only with certain confidence, which may vary from one proposal to another. The overall objective of this thesis is to “Develop a support to the designers using which they can develop environmentally friendly product lifecycles in much the same way as they currently design products, at all stages of their design, while reusing information from their past design activities”. For this the specific objectives are to: 1.Understand how designers currently design products and what they need for developing environmentally friendly product design. 2.Develop a holistic framework for both generation and evaluation of environmentally friendly life cycle proposals. 3. Capture rationale as part of the design process. 4. Estimate uncertainty in the environmental impact assessment during design. 5. Evaluate product lifecycle proposals with multiple criteria under uncertainty. 6. Integrate design process with environmental impact assessment. 7. Apply environmental impact assessment through the design process. From the descriptive studies we found that there is substantial difference in the environmental impact among products having the same functionality generated during the same design process. Analysis of industrial products available in the market show similar results. This means that design can substantially affect the impact created by a product. In our studies, designers did not consider environmental impact as a criterion in evaluation and we also identified the typical activities performed by designers during An Interactive Support for Developing Environmentally Friendly Product Lifecycles designing that must be allowed, supported or taken into account while developing a support for environmentally friendly product lifecycle design (EFPLD). The requirements of the designer for support are: tools should be proactive, easy to learn, understand and use, allow understanding of design rationale, act as a checklist, reduce total time, store knowledge and experience as know‐how backup, useful in all stages of design, not require too much extra effort for analysis, integrated to CAD, aid in trade off between choices, show uncertainty analysis, aid in analysis & improvement, and consider all lifecycle phases. A holistic framework, ACLODS (is a acronym of the six dimensions) constituting the following six dimensions: a) Activities, b) Criteria, c) Lifecycle phases, d) Outcomes, e) Design stages, and f) Product Structure was proposed for development of environmentally friendly product lifecycle designs. Through descriptive studies we found mainly 4 categories and associated sub categories of uncertainty in information with respect to LCA in design. The four categories are uncertainty in product structure, lifecycle phases, data quality, and methodological choices. The sub categories are assemblies, sub- assemblies, parts, relations, and features in product structure, material, production, distribution, usage, and after‐usage in lifecycle phases, temporal relevance, spatial relevance and sample size in data quality, and temporal relevance, spatial relevance, and comprehensiveness in methodological choices. At any point of time, uncertainty in information available is an accrual of the combination of the individual uncertainties. A method called confidence weighted objectives method is developed to compare the whole lifecycle of product proposals using multiple evaluation criteria under various levels of uncertainty. It is compared with normal weighted objectives method and found to be better since it estimates the overall worth of proposal nd confidence on the estimate, enabling deferment of decision making when decisions cannot be made using current information available. A new integrated platform IDEA‐SUSTAIN is developed in this thesis for supporting synthesis in product development on a commercial CAD workspace, while also aiding automated capture and storage of the rationale behind the decisions for retrieval whenever required during design. It is extended to support life cycle assessment of product proposals created by automatically extracting the information already stored while designing and ask for other information required to model the lifecycle without much extra effort from the designer. Then it uses the method for uncertainty reasoning developed also as a part of this research to estimate the level of confidence on the impact value owing to the incompleteness in knowledge available. The estimation is possible at part, assembly or product levels, for a single lifecycle phase or multiple phases. Using in‐house design exercises and feedback questionnaire evaluation of support is done. The usage of Idea‐Sustain has been found to be the best for both generation and evaluation of product proposals. The two computer aided tools – software (LCA) and Idea-Sustain-are compared with each other for fulfilling the functional requirements by analysing the feedbacks given by the designers on these tools against these requirements. Idea‐Sustain fulfilled well most of the requirements while the software (LCA) fulfilled only some of the needs, that too less effectively. 2011-08-03T18:30:00Z http://hdl.handle.net/2005/1383 Title: A Geometric Framework For Vision Modeling In Digital Human Models Using 3D Tessellated Head Scans Authors: Vinayak, * Abstract: The present work deals with the development of a computational geometric framework for vision modeling for performing visibility and legibility analyses in Digital Human Modeling (DHM) using the field-of-view (FoV), estimated geometrically from 3D tessellated head scans. DHM is an inter-disciplinary area of research with the prime objective of evaluating a product, job or environment for intended users through computer-based simulations. Vision modeling in the existing DHM’s has been primarily addressed through FoV modeling using right circular cones (RCC). Perimetry literature establishes that the human FoV is asymmetric due to unrestricted zygomatic vision and restrictions on the nasal side of the face. This observation is neither captured by the simplistic RCC models in DHM, nor rigorously studied in vision literature. Thus, the RCC models for FoV are inadequate for rigorous simulations and the accurate modeling of FoV is required in DHM. The computational framework developed in this work considers three broad components namely, the geometric estimation and representation of FoV, visibility and statistical visibility, and legibility of objects in a given environment. A computational geometric method for estimating FoV from 3D laser-scanned models of the human head is presented in this work. The strong one-to-one similarity between computed and clinically perimetry maps establishes that the FoV can be geometrically computed using tessellated head models, without necessarily going through the conventional interaction based clinical procedures. The algorithm for FoV computation is extended to model the effect of gaze-direction on the FoV resulting in binocular FoV. A novel unit-cube scheme is presented for robust, efficient and accurate modeling of FoV. This scheme is subsequently used to determine the visibility of 3D tessellated objects for a given FoV. In order to carry out population based visibility studies, the statistical modeling FoV and generation of percentile-based FoV curves are introduced for a given population of FoV curves. The percentile data thus generated was not available in the current ergonomics or perimetry literature. Advanced vision analysis involving character-legibility is demonstrated using the unit-cube with an improved measure to incorporate the effect of character-thickness on its legibility. 2011-08-24T18:30:00Z http://hdl.handle.net/2005/1040 Title: Understanding Knowledge Needs And Processes In Design Authors: Vijaykumar, Gokula A V Abstract: In this knowledge economy, organizations are leveraging their competence through the knowledge they possess. Managing knowledge will potentially retain the competence held by the organization if knowledge generated across its projects and units is captured, structured and reused. Even though many tools and techniques are proposed in the literature to support these activities, their adoption in industry has been meagre. This may be due to development of tools without basing them on substantial and careful descriptive studies. This raises the following research issues: the knowledge processes and knowledge sources available in organizations and their characteristics need to be understood better. To address these gaps, following objectives are addressed in this research: ♦ To understand the specific needs and capability of the organization for capture and reuse of product development knowledge and ♦ To evaluate various alternative supports for capture and structure of relevant, evolving product development knowledge for reuse. To address these objectives, two observational studies were conducted in the organizations. To get a broader picture about the knowledge processes occurring in the organization, a KRIT model is proposed which is an acronym for Knowledge of solutions-Requirements-Interactions-Tasks, in which interactions of the designers with people and tools play the central role in processing knowledge during design. The KRIT model is validated through the demonstration of the existence of its nodes and links. From the observations it has been found that interactions ‘designer working with computer’, ‘two designers working with a computer’ and ‘two designers interacting with each other’ are most frequently occurred, and occupied most of the time during designing. Any tools to support knowledge capture and reuse should support these interactions such that capture and reuse can be intuitive and in-built in a natural way into a designer’s work habits. It is emphasized that there is a substantial need to increase the percentage of time spent by designers on capturing knowledge during the design process. This increase in time would lead to decrease in a designers’ time spent on knowledge acquisition and dissemination provided designers are capturing reusable knowledge. To answer capture and reuse of knowledge in detail in the observational studies, a new taxonomy of knowledge is proposed. By linking the representations of argumentation, designer’s activities, and the artefact being designed, we argued that the expressiveness of this taxonomy is high compared to the others proposed in the literature. The taxonomy has three broad categories of knowledge: topics, classes, and activities. Based on the definitions of the factors used in the taxonomy and the analysis of the protocols, the factors in each group under each category are argued to be mutually exclusive. In order to study the links between the proposed categories and factors in the taxonomy of knowledge, a method for converting the questions and answers (from the protocol data) into a generic format is framed. The taxonomy is validated comprehensively, and is able to cover various stages of design. Most of the designers’ time was spent working with a CAD package, in which most of the kinds of knowledge mentioned in the proposed taxonomy of knowledge was neither captured not reused. The important observations noted by comparing the knowledge captured in the preliminary study and the main study are as follows: Compared to the preliminary study, process related information and knowledge are captured higher in the main study. In the main study behavioural related content is captured more; whereas in the preliminary study structural content is captured more. The factors organization, usage, maintenance and sales captured in the preliminary study are not at all captured in the main study. In order to assess the usefulness of the knowledge captured, the kinds of knowledge needs of designers were compared with the kinds of knowledge captured. The important observations about the knowledge needs are: Irrespective of the design stages, in almost 50% of the questions, designers interacted with others to know about old issues or proposals in both the studies. A designer’s time for designing would benefit considerably if the answers for these 50% of the old questions were captured and made available for retrieval in formal documents. In both the studies, proposals based questions played a vital role in the questions analyzed. It shows that considerable proportion of time was spent by the designers on validating, by asking questions, the answers known to them. In contrast to the preliminary study, the designers’ needs for process-related information or knowledge were much higher than that for product-related information or knowledge. Comparing the generic questions obtained from the knowledge needs and knowledge captured reveals that only 14% and 26% with product related content and only 10% and 11.3% of the process based content asked by designers during designing were captured in the preliminary and the main study. These results show that there is a mismatch between knowledge captured and knowledge needed by the designers. This may be one of the primary reasons for the poor usage of documents in the organization. The generic questions generated from the questions asked by the designers and various documents will act as a guideline to the designers for what knowledge and information should and should not to be captured. Due to restrictions in the observations, a questionnaire survey was conducted to achieve the objective to collect 10% of total number of employees’ perspectives about the issues considered in this research. The important observations from the analyses of the collected questionnaire are: Designers’ perceive all types of interactions as important and frequent for information generation and sharing. These results are contradictory to the personal observations in which only interactions ‘designer working with computer’ and ‘two designers working with a computer’ occurred frequently. This shows that designers are unable to identify the kinds of interaction which they perform in their daily activities. Due to this, the information processes occurring within these interactions are not perceptible to the designers. Designers perceive that they get the right information at the right time in only 4 or more out of 10 for most of the times. This perception illustrates there is substantial need for the development of support to satisfy the information needs of designers. Analyses of the types of questions reveal that the question asking behavior of the designers is not static; the major share of questions falling under the category ‘question from answer given’ could be interpreted as: designers often do not frame exact questions to fulfil their requirements; they grab the opportunity to take as much as knowledge as possible during an interaction. Analyses of the types of answers reveal that designers gave more inferences on their answers in order to give a better response, which in turn should help reduce the number of questions subsequently asked especially in the protocol coded as ‘new answer’. Two studies have been used to assess the effectiveness of seven tools for supporting knowledge capture and reuse. The important observations from the initial study are: Mobile E-Notes TakerTM is ranked higher because this equipment provides a blend of properties between the paper and computer. These observations stress the importance of features provided for knowledge generation, modification, capture and reuse in the system. The observations from analyzing the three top rated tools (Mobile E-Notes TakerTM, Tablet with viewing facility and Computer with RhinocerosTM CAD package) to understand influence of these tools on knowledge capture and reuse during conceptual designing are: The differences observed in the percentage of capture between the usage of the three tools demonstrate that tools have an influence on the knowledge capture activity. Even though none of the three tools capture adequate knowledge during designing, Mobile e-Notes TakerTM seems to be the best tool for capture compared to the other two tools, both in the original and redesign experiments. These results suggest that some other mechanisms should be added to these tools so that their effectiveness of capturing could be increased. One mechanism is to incorporate the proposed KRIT model and the taxonomy of knowledge during designing. This integration will be one of the good mechanisms to aid knowledge capture and reuse, because the knowledge capture will occur along with the knowledge creation process. We believe that through this integration the purpose to enhance the knowledge capture and reuse during the design process will be achieved. 2011-01-30T18:30:00Z http://hdl.handle.net/2005/603 Title: Advanced Methodologies For Designing Metallic Armour Plates For Ballistic Impact Authors: Raguraman, M Abstract: A Primary objective of the present research is the development of robust CAE (Computer-Aided Engineering)-based approaches for designing armour plates subjected to ballistic impact by small-calibre hardened peojectiles with or without a protective sheath. Amongst the challenges in simulation is the capturing of target plate material behaviour at high strain rates with possibilities of adiabatic heating. A comprehensive numerical study carried out has resulted in the identification of simulation guidelines using a commercially available explicit finite element anlaysis solver (viz. LS_DYNA). The interferences thus drawn in terms of modeling approach 9I.e. shell, solid or axisymmetric or a mixed representation). Mesh density and element type, contact condition, and constitutive model 9I.e. discrete strain-rate based, Cowper-Symonds, or Johnson-Cook) with failure criteria are verifiable and greatly beneficial for armour plate design. Confidence in the suggested procedures has been obtained through extensive correlation of numerical results with experimental residual velocities and ballistic limits as well as projectile and target plate failure modes. A wide range of impact velocities has been considered (from a low velocity of about 5m/s to an ordnance range velocity of 800+ m/s). Target plates made of variants of mild steel and aluminium alloys have been studied. The simulation approaches have been applied to single-layered as well as multi-layered target plates. Although a majority of the comparisons has been made against published test results, a new ballistic impact testing facility has been set up in course of the current research and excellent correlation of numerically predicted residual velocities and failure modes has been obtained against the tests carried out for aluminium plate using the latter facility. A unique feature of the current experimental effort is the capturing of the complete trajectory of projectile beginning with oblique impact through subsequent perforation/ricochet. Furthermore, projectiles of various nose-shapes such as ogival, conical, hemispherical and blunt have been employed. The power of simulation has been demonstrated with the help of a number of parametric studies with variables such as plate thickness and material properties, as well as projectile mass and diameter, and obtaining physically consistent results. Additionally, existing semi empirical models for residual velocity and ballistic limit prediction have been reviewed, and new user-friendly models have been proposed based on energy conservation and predominant shear plugging failure mode of target plate. Finally, the goal of applying the present research work as a design tool can be well-served by packaging the knowledge gathered here in the form of a user-friendly guide with a graphical user interface(GUI). To this end, an application using MS windows VC++ utilities has been created with the functionalities of: (a) viewing reference LS-DYNA input data files for selecting typical problems of impact on steel and aluminium plates; (b) computing complete lists of strain rate-based material quantities required in LS-DYNA material models like discrete strain rate-based, Cowper-Symonds and Johnson-Cook by specifying the minimum number of easily available quasi-static properties (such as elastic modulus, yield and ultimate strengths, etc.), and (c) estimating residual velocities using the semi-empirical relations for steel and aluminium plates derived in the current work. 2009-09-02T09:56:08Z