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Timing belt systems, usually consisting of a toothed belt and multiple pulleys, are used in many mechanical devices, especially in the internal combustion engine to synchronize the rotation of the crankshafts and the camshafts. When the system operates, the belt teeth will be transmitted by the pulley teeth meshed with them. Timing belt drives can make sure that the engine' s valves open and close properly due to their precise transmission ratio. In this thesis, a quasi-static computational model is developed to calculate the belt load distributions and the torques around pulleys for different timing belt systems. The simplest system is a two-pulley system with one oval pulley and one circular pulley. This computational model is then extended to a two-pulley system with one special-shaped pulley and finally generalized to determine the load conditions for a multi-pulley system with multiple special-shaped pulleys. Belt tooth deflections, tooth loads, belt tension distributions, friction forces, and the effect of friction hysteresis have been taken into consideration. Results of these quantities are solved by a nested numerical iteration method. Periodic torques generated by the varied radius of noncircular pulley are calculated by this computational model to cancel the undesired external cyclic torque, which will increase the life of timing belts. / Master of Science / Timing belt systems, usually consisting of a toothed belt and multiple pulleys, are used in many mechanical devices, especially in the internal combustion engine to synchronize the rotation of the crankshafts and the camshafts. When the system operates, the belt teeth will be transmitted by the pulley teeth meshed with them. Timing belt drives can make sure that the engines valves open and close properly due to their precise transmission ratio. In this thesis, a quasi-static computational model is developed to calculate the belt load distributions and the torques around pulleys for different timing belt systems. The simplest system is a two-pulley system with one oval pulley and one circular pulley. This computational model is then extended to a two-pulley system with one special-shaped pulley and finally generalized to determine the load conditions for a multi-pulley system with multiple special-shaped pulleys. Belt tooth deflections, tooth loads, belt tension distributions, friction forces, and the effect of friction hysteresis have been taken into consideration. Results of these quantities are solved by a nested numerical iteration method. Periodic torques generated by the varied radius of noncircular pulley are calculated by this computational model to cancel the undesired external cyclic torque, which will increase the life of timing belts.

Background: The circular economy has emerged as an alternative to linear approaches to consumption and has the potential to solve the most pressing sustainability issues society faces today. SMEs have a central role in the transition towards a circular economy, as they make up the majority of businesses in Europe. However, the adoption of circular practices has been slower than expected. Researching what is affecting the adoption of these practices could provide answers and insights into how to accelerate this transition.  Purpose: The purpose of this study is to explore the role of organizational climate as a moderator when implementing circular business practices, given its potential to lead to organizational change.  Method: This study follows an interpretive approach through a multiple exploratory case study using two companies. Qualitative semi-structured interviews and observations from the company visits were used as primary data. The empirical data is analyzed through a general coding procedure, where explanation building was used as the approach. The research adds to existing theory through an abductive approach.   Conclusion: By exploring the challenges people face in SMEs, we have found that the organizational climate of the company is a critical factor that can affect the implementation of circular practices. Therefore, we propose that by creating the right climate, organizations could potentially accelerate this transition.

The global unsustainable production and consumption patterns in the fashion and textile industry are a prevailing problem. With the rising trend of European brands reshoring their textile manufacturing and upcoming circular economy frameworks from the EU, the Turkish textile industry may face pressures to transform towards circularity in order to remain competitive. To address the research gap concerning prevalent challenges to implement circularity principles in the critical stage of product design, the purpose of this thesis is to explore the barriers to adopting circular product design in the Turkish textile sector from a manufacturers perspective. This study was conducted in Istanbul with eleven textile and apparel manufacturers of different kinds. To reach a nuanced understanding of each perspective, a qualitative research methodology, through semi-structured interviews with factory managers, was used. The empirical findings of barriers are categorised as internal (financial, responsibility, knowledge) and external (country- and industry-specific). Major internal barriers include prioritising profits over circularity, prioritising customer demand over circular design, and unfamiliarity with key concepts. Country-specific external barriers include lack of competent personnel in Turkey and harsh taxation policies. Industry-level barriers include insufficient resources, limited control over fast-fashion demands, and lack of innovative technologies. This thesis contributes to an increased understanding of the scarcely researched topic and enables practitioners to develop efficient policies and business strategies to ease sustainable business development. Future research is suggested to explore drivers and strategies to apply circular product design within the Turkish textile industry. Additionally, further research can be conducted where this study is replicated but from the perspective of brand retailers with procurement operations in Turkey.

Textil- och modeindustrin är en av de mest miljöförorenande industrierna i världen, med dess resursintensitet och stora mängd producerat avfall. De senaste åren, med start från år 2000 har klädproduktionen fördubblats, medan det genomsnittliga antalet gånger plagget används innan det slängs har minskat. Förändringar i produktionsteknik, konsumtionsmönster och materialval är sannolikt inte tillräckligt för att vända textilindustrins påverkan på miljön. Branschen behöver övergå från den nuvarande linjära ekonomin till en mer cirkulär ekonomi där design spelar en central roll. Denna studie belyser de svenska modeföretagens arbete med cirkulära designstrategier och utforskar hur kunskap om cirkulära strategier från andra branscher skulle kunna hjälpa modebranchen att gå mot ökad cirkularitet. Med hjälp av mixed method undersöktes den svenska modebranschens arbete med cirkulära design strategier och branschens utmaningar för ökad cirkularitet. Studien utforskade även organisationer utanför modebranschen för att avgöra hur deras cirkulära framgångar kan implementeras på modeindustrin. Resultaten visar att medan svenska modeföretag implementerar cirkulära designstrategier regelbundet behöver det inte översättas till ökad total cirkulariteten i deras kollektioner. Studien finner att ett gemensamt mått på cirkularitet inom modeprodukter, en systemförändring där cirkulär design och affärsmodeller implementeras genom hela värdekedjan, och ökat samarbete kombinerat med nödvändig infrastruktur är de mest nödvändiga faktorerna för att öka cirkulariteten inom branschen. / The textile and fashion industry is one of the most environmentally polluting industries in the world, with its resource intensity and large amount of produced waste. In recent years, starting from the year 2000, clothing production has doubled, while the average number of times a garment is used before it is thrown away has decreased. Changes in production technologies, consumption patterns and material choices are likely not, enough to reverse the textile industry's impact on the environment. The industry needs to shift from the current linear economy to a more circular one where design plays a pivotal role. This study sheds light on the Swedish fashion companie's work with circular design strategies and explores how knowledge about circular strategies gained from other industries could help fashion move towards increased circularity. With help of mixed method research the Swedish fashion industry's work with circular design strategies and the industry's challenges for increased circularity were examined. The study also explored organizations outside the fashion industry to determine how their circular successes can be implemented here. The results show that while Swedish fashion companies implement circular design strategies regularly it doesn’t necessary translate into increased overall circularity of their collections. The study finds that a common measure for circularity in fashion products, a systemic change where circular design and business models are implemented throughout the entire value chain, and increased collaboration paired with necessary infrastructure are the most necessary factors to increase circularity within the industry.

Purpose: The study aims to identify essential barriers, enablers, and incentives for including circular requirements in tender specification, to facilitate the transition from linear to circular public procurement within the railway industry, thus enhancing a circular economy. This by answering the following research questions: RQ1: What barriers and enablers for circular public procurement within the railway industry exist, and how can the enablers overcome the barriers to facilitate the transition from linear to circular public procurement to enhance a circular economy? RQ2: How can public procurers be incentivized to undergo a transition from linear to circular public procurement within the railway industry? Method: To fulfill the purpose a qualitative case study has been carried out within the Swedish railway industry, focusing on rail vehicle procurement. The exploratory study is of an abductive approach where data have been collected through 22 semi structured interviews which were analyzed through the use of content and thematic analysis. Findings: The study results in a framework visualizing how identified barriers and enablers correspond, along with identified incentives for circular public procurement. The enablers: increase circular economy awareness, increase collaboration between procurer and supplier, translate circularity to economical terms and develop new approaches to circular requirement management are presumed to not only facilitate transition towards circular public procurement but also enhance a circular economy. Theoretical and practical contributions: This study contributes to the scarcity of literature on circular public procurement, especially within the railway industry. Firstly, by identifying the need for procurers and suppliers to collaborate before the initial stage of the public procurement process to increase awareness of circular economy, thus enabling circular requirement management. Secondly, by identifying incentives for circular public procurement. / Syfte: Studien syftar till att underlätta övergången från linjär till cirkulär offentlig upphandling inom järnvägsindustrin för att främja en cirkulär ekonomi, genom att identifiera barriärer, möjligheter och incitament för att inkludera mer cirkulära krav i kravspecifikationen. Följande två forskningsfrågor ämnas att besvaras: RQ1: Vilka barriärer och möjliggörare för cirkulär offentlig upphandling inom järnvägsindustrin existerar, och hur kan möjliggörarna överbrygga barriärerna för att underlätta övergången från linjär till cirkulär offentlig upphandling för att främja en cirkulär ekonomi? RQ2: Hur kan offentliga upphandlare motiveras att genomgå en övergång från linjär till cirkulär offentlig upphandling inom järnvägsbranschen?  Metod: För att uppfylla studiens syfte har en kvalitativ fallstudie inom järnvägsindustrin genomförts, med fokus på upphandling av spårfordon. Den utforskande studien har en abduktiv ansats, där data har samlats in genom 22 semistrukturerade intervjuer som analyserats genom innehålls- och tematisk analys.  Resultat: Studien resulterar i ett ramverk som visualiserar hur identifierade möjliggörare korrelerar med barriärer, samt de identifierade incitament för cirkulär offentlig upphandling. Möjliggörarna: öka medvetenheten kring cirkulär ekonomi, öka samarbete mellan upphandlare och leverantör, översätt cirkularitet till ekonomiska termer och utveckla nya metoder för cirkulär kravhantering antas inte bara underlätta övergången från linjär till cirkulär offentlig upphandling, utan också främja en cirkulär ekonomi.  Teoretiska och praktiska bidrag: Studie bidrar till bristen på litteratur inom cirkulär offentlig upphandling, särskilt inom järnvägsindustrin. Genom att först identifiera behovet av att upphandlare och leverantörer samarbetar före den inledande fasen av upphandlingsprocessen för att öka medvetenheten om cirkulär ekonomi och möjliggöra hantering av cirkulära krav. För det andra genom att identifiera incitament för cirkulär offentlig upphandling.

Purpose: This thesis aims to contribute to the literature on how the value chain for electronic components can be leveraged to obtain circular business models (CBM). By implementing activities in the value chain, circular economy (CE) can be enhanced and a circular value chain obtained. The purpose lies in mapping out activities in the value chain of electronic components and existing barriers to acknowledge where circularity can be increased by CE strategies. Based on this observation, the future path towards CBM will be facilitated. This thesis aims to answer the following research questions: What are the main barriers for a circular value chain in electronic components? and How can the transformation towards a CBM for electronic components be facilitated by a circular value chain?  Method: A qualitative case study has been carried out at Volvo CE. The study is of an abductive approach, where previous theories on CE strategies and value chains were utilised to understand how the transformation towards a CBM can be applied for electronic components. A literature review of the key concepts was conducted and primary data was collected through interviews and one focus group for validation. The data has been analysed through the use of a thematic analysis. Findings: Findings suggest that four areas are of high importance in a circular value chain for electronic components: management, technology department, suppliers relations and aftermarket. The main barriers hindering CE are insufficient objectives, inadequate external value chain integration, limited education, and inertia in technological development. Findings show that the barriers can be mitigated through enhancing CE in the following activities: strategy and organisational vision; cooperation and partners; education and qualifications; innovation and technical development. The result presents how the circular value chain is interconnected with a CBM, visualising how the key activities will facilitate the transformation towards a CBM.  Theoretical contributions & managerial implications: This thesis contributes to the scarcity of literature on value chains in electronic components and adds to research on the connection between value chains and circular business models. The thesis can act as guidance for managers when making the transformation towards a CBM, by highlighting how CE activities can be applied for a more circular value chain.  Limitations and future research: This is a single case study, making the study limited in how applicable the findings are to other industries and countries. Future studies can validate the result by examining value chains in similar companies, to improve the generalisability of our result. This thesis is limited to investigating the value chain from a strategic perspective and we acknowledge that a mapping of the operational value chain can be a matter for future research. We focus on collaboration, but operations that enhance CE in daily activities in production of electronic components are yet to be investigated.

The construction industry is one of the most resource-intensive industries in the world, therefore, scientists, the industry and governments are pushing  for a transition to a Circular Economy (CE) within the industry to address this issue. This study explores the barriers to CE transition within the construction industry, examining how these barriers are perceived by practitioners and contrasting them with academic perspectives in the literature. The barriers identified in the literature were categorized via industrial transition theory based on the regime actors of the Multi-level perspective on transition framework by Geels & Schot (2007) and then aggregated via subcategories based on similarities in barrier definition presented in the literature. By interviewing 8 respondents, 28 barriers to CE transition were found within the categories and subcategories of data coding. The findings revealed that the industry is cautious about CE, which is impeding the drive for transition and affecting further perception and awareness of the concept. Furthermore, it is crucial to investigate barriers individually and how they are interconnected to others, as they collectively contribute to the low and slow progress of industrial transition toward CE in the construction industry.

The current prevailing take-make-waste economy has caused the global climate crisis, operating outside the Planetary Boundaries of our planet (Rockström et al., 2009), disrupting nature's balance and affecting all life on earth (WWF and Global Footprint Network, 2019). Both the European Commission and the European Environmental Agency (EEA) sees the transition to a circular economy (CE) within the product category: textiles, apparel and fabrics as a priority to address the climate impact of the textile and clothing industry (Manshoven et al., 2019). Even though there is much research done on how design and products can help companies transition to a CE, there is still an unexplored dimension of the role that consumers play in this transition. Thus, this master thesis aims to fill this research gap by exploring consumer behaviour in different consumption phases as well as the role of consumers in the circular textiles economy and investigate how sustainable clothing companies can design to engage consumers in a circular behaviour and role. By doing so, it is hoped to contribute to a better understanding of the dimension of the consumer in the circular textiles economy and to identify ways to fulfill the CE principle - keep products and materials in use. The study was conducted through a novel implementation of Research through Design in combination with Interactive Research by using the Design Thinking framework as a research process. The research was executed in close collaboration with the Swedish outdoor clothing company Houdini Sportswear.  The results show that a number of Circular Consumer Behaviours are desired to be acted out in four identified phases of a Circular Clothing Consumption Process: Lifestyle Creation, Product Acquisition, Product Use and Product Dispossession. Furthermore, it was found that the role of the Circular Consumer is very complex and consists of various sub-roles on four layers: Functional, Emotional, Life Changing and Social Impact. On the basis of this knowledge, the theoretical concept of Design for Circular Consumers was developed. On the basis of this theory, the Design for Circular Consumers Tool was created as the key contribution of this thesis. This tool facilitates the design of experiences that engage consumers in the circular textiles system and subsequently support clothing companies in their transition to circular business models as a way to address the climate impact of the textiles industry.