Redesign methodology for mechanical assembly

Design for assembly is the concept of carrying out critical thought early in the design stage to create assembly easement at the production stage. In the aerospace industry, products have very long lives, frequently being optimised rather than introducing new products. This has meant older products, which are stable income generators, have not benefited from the latest design for assembly methods and manufacturing technology suffers from obsolescence. It has been established that a large percentage of overall product cost is determined at the design stage; thus, existing products suffer from preloaded costs. This paper takes existing design for assembly methodologies and analyses them with respect to the unique challenges involved in legacy product redesign. Several novel factors that contribute to redesign analysis are identified such obsolescence impact and a holistic operation difficulty assessment. A tool is developed to identify potential redesign for assembly projects. The tool is demonstrated through the application of real data and comparing against business decisions. The tool was found to provide a strong indication of where profitable projects may be launched

A Method for Visualizing the Structural Complexity of Organizational Architectures

To achieve a high level of performance and efficiency, contemporary aerospace systems must become increasingly complex. While complexity management traditionally focuses on a product’s components and their interconnectedness, organizational representation in complexity analysis is just as essential. This thesis addresses this organizational aspect of complexity through an Organizational Complexity Metric (OCM) to aid complexity management. The OCM augments Sinha’s structural complexity metric for product architectures into a metric that can be applied to organizations. Utilizing nested numerical design structure matrices (DSMs), a compact visual representation of organizational complexity was developed. Within the nested numerical DSM are existing organizational datasets used to quantify the complexity of both organizational system components and their interfaces. The OCM was applied to a hypothetical system example, as well as an existing aerospace organizational architecture. Through the development of the OCM, this thesis assumed that each dataset was collected in a statistically sufficient manner and has a reasonable correlation to system complexity. This thesis recognizes the lack of complete human representation and aims to provide a platform for expansion. Before a true organizational complexity metric can be applied to real systems, additional human considerations should be considered. These limitations differ from organization to organization and should be taken into consideration before implementation into a working system. The visualization of organizational complexity uses a color gradient to show the relative complexity density of different parts of the organization

A Structured Approach for Synchronising the Applications of Failure Mode and Effects Analysis

Failure Mode and Effects Analysis (FMEA) is a systematic approach for evaluating the potential failure modes in a system, and is mainly employed in three distinct tasks labelled: (1) Functional FMEA – evaluating those failures associated with product functional definition, (2) Design FMEA – analysing those failures associated with design definition and (3) Process FMEA – assessing potential failures in manufacturing and assembly processes. The lit-erature review has shown limited works on the field of synchronising these different tasks into a working model. To address this gap, this research developed a framework for integrating these tasks of FMEAs, and then qualita-tively validating the proposed framework. This research adopted a semi-structured questionnaire to collect ex-perts’ feedback and validate the proposed framework. The t-test was then employed to evaluate the collected feedback. The findings highlight that the proposed framework is applicable and could facilitate the synchronisa-tion of the different tasks of FMEA. This research presents a methodological approach for executing and synchro-nising FMEAs. Therefore, the proposed framework is practically relevant as an aid for the practitioners in catching the cascading failures and reducing the relevant impact

Design and Applications of Additive Manufacturing and 3D Printing

Additive manufacturing (AM), more commonly known as 3D printing, has grown trememdously in recent years. It has shown its potential uses in the medical, automotive, aerospace, and spare part sectors. Personal manufacturing, complex and optimized parts, short series manufacturing, and local on-demand manufacturing are just some of its current benefits. The development of new materials and equipment has opened up new application possibilities, and equipment is quicker and cheaper to use when utilizing the new materials launched by vendors and material developers. AM has become more critical for the industry but also for academics. Since AM offers more design freedom than any other manufacturing process, it provides designers with the challenge of designing better and more efficient products

Over zorgvuldige veehouderij : veel instrumenten, één concert

"Onder een zorgvuldige veehouderij verstaan we een modern ingerichte en economisch vitale veehouderij, die garant staat voor een goede omgang met dieren, een nauwkeurige naleving van professionele waarden en waarmee een goede boterham kan worden verdiend." In totaal 62 onderzoekers beschrijven in 30 essays actuele inzichten, ieder vanuit hun kijk op de verschillende aspecten van de veehouderij. De breedte van die visie is onontbeerlijk. Er is niet één oplossing, maar er zijn vele wegen die naar Rome leiden. Een simpel spoorboekje, dat de kortste route geeft naar de plaats van bestemming, is er in dit geval niet. . . . Met deze essaybundel hoopt Wageningen UR het debat over de toekomst van de veehouderij te verrijken. Met de kennis die we hebben of kunnen genereren willen we laten zien dat het mogelijk is om samen met bedrijfsleven, overheid en (bezorgde) burgers oplossingen uit te werken voor de prangende maatschappelijke vraagstukken. Want: 'kennisinstellingen en hun leden moeten een actieve rol spelen in de maatschappelijke discussie', aldus Rudy Rabbinge en Pieter Winsemius in hun voorwoord."(Van Wageningen UR nieuws http://www.wur.nl/NL/nieuwsagenda/nieuws/P004.htm

Architecting complex systems for robustness

Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2007.Vita.Includes bibliographical references (p. 121-128).Robust design methodologies are frequently utilized by organizations to develop robust and reliable complex systems. The intent of robust design is to create systems that are insensitive to variations from production, the environment, and time and use. While this process is effective, it can also be very time consuming and resource intensive for an engineering team. In addition, most robust design activity takes place at the detailed design phase, when the majority of the product life cycle cost has already been committed. Addressing robustness and the "ilities" at the architecture level may be more effective because it is the earliest and highest leverage point in the product development process. Furthermore, some system architectures are inherently more robust than others. In this thesis, a framework based on principles is proposed to architect complex systems for type I and II robustness. The principles are obtained by tracing the architectural evolution of the jet engine, which is an extremely complex system that has evolved to high reliability. This framework complements existing robust design methods, while simultaneously incorporating the robustness focus earlier in the product development process.by Jason C. Slagle.S.M

Understanding robustness as an image of sustainable agriculture

The general aim of the research described in this thesis is to contribute to a better understanding of the conceptualisation of robustness in agricultural science as well as its relevance to sustainability. Robustness rapidly gained attention as a potential solution for a variety of problems that characterize modern agriculture. The Dutch innovation programme “TransForum” considered robustness an important societal value that needed to be developed in relation to innovations for sustainable development of the Dutch agri-sector. However, its meaning to agriculture is unclear, the term is loosely being used in various contexts and has been given equally diverse meanings in different fields of science. This project takes a conceptual approach to analyse what robustness is and how is it approached in different fields of science, and addresses the question how these approaches relate to sustainability. The empirical part of the research concentrates on conceptualisations of robustness in practice. Cases are used to study which conceptualisation(s) are being worked out in agriculture. The relevance of robust agriculture vis-à-vis sustainable agriculture is discussed. In chapter 2 it is argued that robustness should not be seen as a clear-cut system feature, but rather as a multi-interpretable flip-side of a specific vulnerability aspect or as a description of a particular notion of system stability. Robustness claims have meaning only when the vulnerability of the system is made explicit. Vulnerability is considered to be constituted by one or more vulnerability aspects: exposure, sensitivity and non-resilience. Sensitivity and non-resilience refer to system properties that are revealed when a system is exposed to perturbations, while exposure refers to the degree, duration and extent to which a system is subjected to such perturbations. As a flip side of vulnerability, robustness can be considered accordingly: as a system property describing a capacity to cope with potential perturbations, or as a relational property of system and environment together, referring to a capacity to avoid exposure and keep perturbations at a distance. Whether or not we call a system robust depends on the structural or functional impact that a perturbation may have on the system. From high to low impact, the following results of perturbations are distinguished (chapter 2): Permanent loss of structure and function; Permanent change of structure and/or function (adaptation); Temporary loss of structure and/or function; Preservation of structure and function (resistance); Non-exposure It is concluded that robustness should be seen as an intermediate sphere between a vulnerability aspect and its opposite notion of stability. The term “robustness state” is introduced to refer to such intermediate spheres. From low to high inclination to follow environmental changes, three robustness states are distinguished: (1) a state of avoiding exposure, (2) a state of inherent resistance, and (3) a state of response and recovery after being perturbed. Determined efforts to approach or enhance any robustness state are referred to as robustness strategies. Chapter 3 discusses the relevance of robustness as an image of sustainability. It is argued that robustness has conceptual advantages against sustainability because it is embedded in system thinking and gives direction to operationalisations of sustainable development more than sustainability ever can. This chapter presents a framework against which the robustness conceptualisations of three TransForum projects which were set up to develop the concept of robustness in agricultural innovation are assessed. These projects were: ‘Stacking functionality expressed in apple genes’. The aim of this project was the development of high-quality apple varieties that have a durable resistance to apple scab (Venturia inaequalis) by means of cisgenesis; ‘A monitoring and control system for conditioning of plants and greenhouses’. The project aimed to quantify physiological effects of climate conditions on plants in energy efficient and energy producing greenhouses, and develop intelligent crop monitoring systems of plant performance; ‘Robustness of animal production systems’. The main objective of this project was to develop the concept of robustness of animal production systems at various levels using system and control theory and apply these concepts to cases in the production system (farm), the production chain and at regional level. It is observed that in these projects, robustness was conceptualised from an engineering perspective in relation to system efficiency and control. Considering the benefits of other conceptualisations it is suggested that these should be taken into account when operationalising sustainable development through robustness. The growing interest in complex (adaptive) systems and alternative system approaches within the agricultural sciences requires a wider scope of robustness thinking. The dominant engineering approach to robustness in agriculture has unremittingly added complexity to agricultural systems and has steered agricultural production systems towards states of Highly Optimized Tolerance (HOT), susceptible to spiralling complexity to suppress unwanted vulnerabilities and take advantage of opportunities for increased performance. The drawback of optimized tolerance is fragility to unexpected events, and the result of spiralling complexity is a robust, yet fragile system, i.e. high tolerance to anticipated disturbances, combined with extreme fragility to unexpected events. Chapter 4 discusses the potential of Reflexive Interactive Design (RIO) to break through the self-enhancing process of complexity/robustness spiralling, i.e. optimising the production potential of desired outputs, while deliberately integrating resilience and adaptive cycles of co-evolving sub-systems in the production system. Taking the Houden van Hennen (HVH) project as a case, in this chapter the needs of farmer, laying hen and citizen, as compiled by the project team, are categorized in terms of the robustness strategies that are introduced in chapter 2, and their distribution over the social, biological and technological subdomain of the system. The results show that of all needs to cope with potential disturbances, 86% relates to avoiding exposure. Strategies to cope with disturbances were predominantly found in the social-technical sphere, while the vulnerability perception of the laying hen husbandry system in the HvH project concentrated at the animal level. The use of their natural behaviour and adaptive capacities to cope with disturbances seems motivated by system optimisation and purposefully placed under care of the farmer. These results illustrate that designing for robustness in livestock production systems does not break through complexity/robustness spiralling. In other words, livestock production systems tend to develop robustness against well-known stressors. Even though calls for robustness are frequently initiated by an experienced lack of adaptive capacity to new and unexpected developments, solutions are generally found in increased adaptedness to existing stakeholder demands. An example of a new system vulnerability that arises along the complexity/robustness spiral in husbandry systems is the risk of damaging behaviour that appears to increase with trends to create larger groups and the desire to ban beak trimming and tail docking. In chapter 5 it is argued that the incidence of damaging behaviour is not determined by rearing conditions only, and that selection on individual traits cannot solve problems caused by interactions between animals. Robustness as a breeding goal should therefore relate to performance of the group as whole, rather than to individual performance. The capacity of animals to cope with various perturbations and fluctuations can be influenced at many different levels. Early life experiences and organisation of the environment in which animals are reared, can support their capacity to adapt in later life and contribute to the overall robustness of system. The general discussion (chapter 6) combines the conceptual analyses and empirical data to consider the relevance of robustness vis-à-vis agricultural sustainability. It is argued that three main approaches to robustness are particularly relevant for agriculture: 1. engineering approaches, focusing on optimization and maintenance of efficiency of function; 2. biological approaches, focussing on fitness and resistance; and 3. ecology approaches, focusing on recovery and structural persistence. From a sustainability perspective, the engineering approach has value especially in the economic domain, and relevance only when robustness criteria can be quantified. The biological approach has value from a social sustainability perspective. It is accessible to ideological considerations and value judgements. The ecology approach, most notably the amplitude conceptualisation to robustness has value in sustainability studies of social-ecological and social-economic systems and is particularly relevant to study the dynamics of complex adaptive systems. A plea is made for a holistic approach to robustness in agriculture, referring to homoiothermism as an example of holistic robustness. It is argued that robustness is a far more tangible concept than sustainability and that it could function as an image of sustainability. Due to its contested nature, robustness can profit from a fundamentally positive attitude of various stakeholders while simultaneously applying to specific systems and sustainability attributes.</p