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Linköpings universitet Institutionen för ekonomisk och industriell utveckling

Overview
Works: 1,401 works in 1,580 publications in 1 language and 1,569 library holdings
Roles: Publisher, pub, Other
Publication Timeline
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Most widely held works by Linköpings universitet
Optimization and robustness of structural product families by Michael Öman( Book )

3 editions published between 2009 and 2011 in English and held by 3 WorldCat member libraries worldwide

This thesis concerns structural optimization and robustness evaluations, and new methods are presented that considerably reduce the computational cost of these evaluations. Optimization is an effective tool in the design process and the interest from industry of its usage is quickly increasing. However, the usage would probably have grown faster if the required number of computationally costly finite element analyses could be reduced. Especially in the case of product family optimization, the problem size can easily get too large to be solved within a reasonable time. This is sometimes also true for robustness evaluations. To enable the usage of optimization and robustness evaluations also for large scale industrial problems, two new methods are here presented, which require a considerably smaller number of finite element analyses. The first method concerns structural optimization of product families subjected to multiple crash load cases. Here, the number of required finite element analyses are considerably reduced by only considering the critical constraint in each iteration step. The second method is an approach to approximate the variable sensibility based on the distribution of internal energy in a structure. The method can be used to evaluate the relative robustness of different design proposals or for structural optimization. Since the method is independent of the number of parameters and design variables the computational cost of such evaluations is drastically reduced for computationally large problems
Industrial symbiosis in the biofuel industry quantification of the environmental performance and identification of synergies by Michael Martin( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

The production of biofuels has increased in recent years, to reduce the dependence on fossil fuels and mitigate climate change. However, current production practices are heavily criticized on their environmental sustainability. Life cycle assessments have therefore been used in policies and academic studies to assess the systems; with divergent results. In the coming years however, biofuel production practices must improve to meet strict environmental sustainability policies. The aims of the research presented in this thesis, are to explore and analyze concepts from industrial symbiosis (IS) to improve the efficiency and environmental performance of biofuel production and identify possible material and energy exchanges between biofuel producers and external industries. An exploration of potential material and energy exchanges resulted in a diverse set of possible exchanges. Many exchanges were identified between biofuel producers to make use of each other’s by-products. There is also large potential for exchanges with external industries, e.g. with the food, energy and chemical producing industries. As such, the biofuel industry and external industries have possibilities for potential collaboration and environmental performance improvements, though implementation of the exchanges may be influenced by many conditions. In order to analyze if concepts from IS can provide benefits to firms of an IS network, an approach was created which outlines how quantifications of IS networks can be produced using life cycle assessment literature for guidelines and methodological considerations. The approach offers methods for quantifying the environmental performance for firms of the IS network and an approach to distribute impacts and credits for the exchanges between firm, to test the assumed benefits for the firms of the IS network. Life cycle assessment, and the approach from this thesis, have been used to quantify the environmental performance of IS networks by building scenarios based on an example from an IS network of biofuel producers in Sweden. From the analyses, it has been found that exchanges of material and energy may offer environmental performance improvements for the IS network and for firms of the network. However, the results are dependent upon the methodological considerations of the assessments, including the reference system, functional unit and allocation methods, in addition to important processes such as the agricultural inputs for the system and energy systems employed. By using industrial symbiosis concepts, biofuel producers have possibilities to improve the environmental performance. This is done by making use of by-products and waste and diversifying their products, promoting a transition toward biorefinery systems and a bio-based economy for regional environmental sustainability
Fluid power systems for mobile applications : with a focus on energy efficiency and dynamic characteristics by Mikael Axin( Book )

2 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

Metamodel-based design optimization : a multidisciplinary approach for automotive structures by Ann-Britt Ryberg( Book )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

Automotive companies are exposed to tough competition and therefore strive to design better products in a cheaper and faster manner. This challenge requires continuous improvements of methods and tools, and simulation models are therefore used to evaluate every possible aspect of the product. Optimization has become increasingly popular, but its full potential is not yet utilized. The increased demand for accurate simulation results has led to detailed simulation models that often are computationally expensive to evaluate. Metamodel-based design optimization (MBDO) is an attractive approach to relieve the computational burden during optimization studies. Metamodels are approximations of the detailed simulation models that take little time to evaluate and they are therefore especially attractive when many evaluations are needed, as e.g. in multidisciplinary design optimization (MDO). In this thesis, state-of-the-art methods for metamodel-based design optimization are covered and different multidisciplinary design optimization methods are presented. An efficient MDO process for large-scale automotive structural applications is developed where aspects related to its implementation is considered. The process is described and demonstrated in a simple application example. It is found that the process is efficient, flexible, and suitable for common structural MDO applications within the automotive industry. Furthermore, it fits easily into an existing organization and product development process and improved designs can be obtained even when using metamodels with limited accuracy. It is therefore concluded that by incorporating the described metamodel-based MDO process into the product development, there is a potential for designing better products in a shorter time
Multi-Threaded Distributed System Simulations Using Bi-Lateral Delay Lines by Róbert Braun( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

As the speed increase of single-core processors keeps declining, it is important to adapt simulation software to take advantage of multi-core technology. There is a great need for simulating large-scale systems with good performance. This makes it possible to investigate how different parts of a system work together, without the need for expensive physical prototypes. For this to be useful, however, the simulations cannot take too long, because this would delay the design process. Some uses of simulation also put very high demands on simulation performance, such as real-time simulations, design optimization or Monte Carlo-based sensitivity analysis. Being able to quickly simulate large-scale models can save much time and money. The power required to cool a processor is proportional to the processor speed squared. It is therefore no longer profitable to keep increasing the speed. This is commonly referred to as the "power wall". Manufacturers of processors have instead begun to focus on building multi-core processors consisting of several cores working in parallel. Adapting program code to multi-core architectures constitutes a major challenge for software developers. Traditional simulation software uses centralized equation-system solvers, which by nature are hard to make parallel. By instead using distributed solvers, equations from different parts of the model can be solved simultaneously. For this to be effective, it is important to minimize overheadcosts and to make sure that the workload is evenly distributed over the processor cores. Dividing an equation system into several parts and solving them separately means that time delays will be introduced between the parts. If these occur in the right locations, this can be physically correct, since it also takes some time for information to propagate in physical systems. The transmission line element method (TLM) constitutes an effective method for separating system models by introducing impedances between components, causing physically motivated time delays. Contributions in this thesis include parts of the development of the new generation of the Hopsan simulation tool, with support for TLM and distributed solvers. An automatic algorithm for partitioning models has been developed. A multi-threaded simulation algorithm using barrier synchronization has also been implemented. Measurements of simulation time confirm that the simulation time is decreased almost proportionally to the number of processor cores for large models. The decrease, however, is reduced if the cores are divided on different processors. This was expected, due to the communication delay for processors communicating over shared memory. Experiments on real-time systems with four cores show that a four times as large model can be simulated without losing real-time performance. The division into distributed solvers constitutes a sort of natural cosimulation. A future project could be to use this as a platform for linking different simulation tools together and simulating them with high performance. This would make it possible to model each part of the system in the most suitable tool, and then connect all parts into one large model
On Manufacturing Technology as an Enabler of Flexibility Affordable Reconfigurable Tooling and Force-Controlled Robotics by Marie Jonsson( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

För att överleva och växa på dagens globala arena försöker många tillverkande företag vara flexibla, och korta sin produktutveckling och sina ledtider för att på så sätt snabbare kunna möta marknadens krav. Den utrustning som används i produktionen lägger grunden för hur enkelt systemet kan anpassa sig till förändringar vilket gör att den teknik som används för tillverkningen är en viktig byggsten för att möjliggöra flexibilitetet. Industrirobotar och fixturer är vanliga typer av utrustning som används för tillverkning. Industrirobotar är mångsidiga, omprogrammeringsbara enheter och kan till exempel användas för svetsning, förflyttning av gods etc. De har traditionellt sett haft svårt att hantera avvikelser vilket har gjort att höga krav ställts på inkommande material och omgivande utrustning. Detta har i sin tur lett till att om ett visst mått av flexibilitet krävts, så har manuell arbetskraft föredragits framför robotar. Ett sätt att öka förmågan att hantera relativt "okända" miljöer är att integrera sensorer med produktionsutrustning, för att på så sätt få information om tillverkningens förutsättningar. Kraftsensorer tillsammans med kontrolllogik, gör det möjligt för en robot att reagera på kraft. Detta är användbart om roboten skall användas för avgradning och slipning, eller för montering, tillverkningstyper som annars har varit svåra att automatisera. Fixturer är enheter som håller en produkt i önskat läge under tillverkningsprocessen. En fixtur har traditionellt konstruerats för att passa en produkt och en process. De har således inte kunnat användas t.ex. för olika produkt-typer eller när produkter förändrats på något sätt, vilket har påverkat systemets flexibilitet negativt. Sensorer, som t.ex. olika mätsystem kan användas för att frikoppla en fixturs struktur från dess interna noggrannhetskedja, något som annars är ett vanligt sätt att uppnå önskad noggrannhet i fixturen. Det tidigare utvecklade ART konceptet (Affordable Reconfigurable Tooling ungefär Kostnadseffektiva Rekonfigurerbara Verktyg) bygger på denna princip. ART fokuserar på att öka flexibiliteten för fixturer samtidigt som de fortfarande är resurseffektiva. Denna avhandling behandlar hur vanligt förekommande produktionsutrustning, såsom robotar och fixturer, kan kombineras med sensorer för att uppnå ökad flexibilitet i tillverkning. Den genomförda forskningen visar att kraftstyrda robotar möjliggör ett bra och jämt resultat vid montering av icke formstabila strukturer/komponenter och vid komplicerad slipning/gradning av gjutgods. Kraftstyrningen gör att systemet klarar av att hantera variation hos de bearbetade/monterade detaljerna. Den minskar också behovet av noggrannhet hos omgivande utrustning, såsom fixturer och gripdon, och både förenklar och ökar säkerheten vid programmering jämfört med traditionella metoder. För att passa de industriella förutsättningarna skulle dock parameterinställning och användarvänlighet behöva utvecklas ytterligare. Genom att använda mätsystem tillsammans med fixturer har nya fixturenheter till ART utvecklats. Dessa enheter minskar resursåtgången vid sammanbyggnad och omkonstruktion av fixturer. De öppnar även för att aktiva fixturer som är mer lika robotar, men som fortfarande är kostnadseffektiva. ART påverkar också design av fixturer positivt, eftersom stödjande mjukvaruverktyg för design kan tas fram. Det övergripande resultatet tyder på att de använda sensorerna tillsammans med nydanande teknik ger mervärde i applikationer som montering och slipning. Vidare så visar forskningen att det är möjligt att öka flexibiliteten på flera nivåer i tillverkningssystemet med sensorer i kombination med industrirobotik och fixturer
Knowledge integration and innovation in buyer-supplier collaborations by David T Rosell( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

Research indicates buyer-supplier collaborations in new product development (NPD) can have a positive impact on innovation. From a knowledge based view, it is argued that suppliers add a complementary knowledge base that is combined with the buyer's knowledge. But what does the supplier contribution actually consist of? And more importantly: How is this supplier knowledge integrated into the NPD process? This is not clear in the literature. Different supplier inputs may imply different knowledge integration mechanisms and practices. The purpose of this licentiate thesis is to investigate how supplier knowledge is integrated into the NPD process. The focus is to explore how knowledge intensive manufacturing firms integrate different supplier inputs in collaborative NPD projects by using different knowledge integration mechanisms. To fulfil the aim of thesis a qualitative approach has been applied and by studying NPD processes in three industrial sectors. An extensive literature review and a focus group meeting are followed by two qualitative case studies that are based mainly on interviews with keyrepresentatives in the buyer-supplier collaborations. The first study investigates different supplier contributions by categorizing different supplier inputs. The second study - which is the largest part of the overall study - investigates how supplier knowledge is integrated in NPD collaborations using different integration mechanisms. Here, six NPD collaborations, representing the automotive, the energy, and the telecom sectors, are studied and compared, in order to understand the integration processes and the different knowledge integration mechanisms. The third study investigates the role of trust in capturing supplier knowledge. Here, two NPD collaborations which can be considered to be polar-cases in terms of scope and depth are compared in order to explore and explain the role of trust in the integration processes. Altogether these studies lay a foundation for a model of knowledge integration between the buyer and the supplier in NPD collaborations. The model identifies two main strategies for integrating supplier knowledge - knowledge absorption and joint knowledge accumulation. Knowledge absorption concerns innovation processes where the contribution from suppliers is focused on product- and process improvements, i.e. incremental input. Here, the development is dictated by clear specifications. Supplier contacts take place during a limited period of time and are restricted to certain phases in NPD projects. Thus, the main knowledge integration mechanism used is sequencing. In these situations, the buyer actually tries to capture and absorb the knowledge of the supplier at a specific point in the process. A basic level of trust, based on the reputation the supplier has for competence is sufficient. Joint knowledge accumulation, on the other hand, is how firms manage more radical input from suppliers, such as new technology or new design. In these cases, knowledge integration strategies extend over a longer period of time, throughout several phases of the NPD project. There is a high degree of interaction between the people involved, to find new solutions. The main knowledge integration mechanism is group problem-solving. Knowledge is jointly accumulated by sharing, combining, and creating new knowledge in open processes. In these cases, a profound level of trust is required. When integrating supplier knowledge in innovation, management has to consider the possible and preferred outcome of the collaboration; it might be a commercial deal to provide for a temporary access to knowledge, or it might be a long-term alliance, where joint learning is an aim. In the first case, a traditional NPD process with clear specifications, using sequencing and technological interfaces, will be adequate. In the second case, focus should be on interpersonal problem solving between trustworthy individuals
Oxidation behaviour of MCrAlX coatings : effect of surface treatment and an Al-activity based life criterion by Pimin Zhang( )

3 editions published in 2018 in English and held by 3 WorldCat member libraries worldwide

Thermal Barrier Coatings : Durability Assessment and Life Prediction by Robert Eriksson( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

Thermal barrier coating (TBC) systems are coating systems containing a metallic bond coat and a ceramic top coat. TBCs are used in gas turbines for thermal insulation and oxidation resistance. Life prediction of TBCs is important as high-temperature exposure degrades the coatings through mechanisms such as thermal fatigue and the formation and growth of thermally grown oxides (TGOs). This thesis presents research on durability assessment and life prediction of air plasma sprayed TBCs. The adhesion of thermal barrier coatings subjected to isothermal oxidation, thermal cycling fatigue and thermal shock was studied. The adhesion strength and fracture characteristics were found to vary with heat treatment type. The influence of interdiffusion between bond coat and substrate was studied on TBCs deposited on two different substrates. The thermal fatigue life was found to differ between the two TBC systems. While fractography and nanoindentation revealed no differences between the TBC systems, the oxidation kinetics was found to differ for non-alumina oxides. The influence of bond coat/top coat interface roughness on the thermal fatigue life was studied; higher interface roughness promoted longer thermal fatigue life. Different interface geometrieswere tried in finite element crack growth simulations, and procedures for creating accurate interface models were suggested. The influence of water vapour and salt deposits on the oxidation/corrosion of a NiCoCrAlY coating and a TBC were studied. Salt deposits gave thicker TGOs and promoted an Y-rich phase. The effect of salt deposits was also evident for TBC coated specimens. A microstructure-based life model was developed using the Thermo-Calc software. The model included coupled oxidation-diffusion, as well as diffusion blocking due to the formation of internal oxides and pores. The model predicted Al-depletion in acceptable agreement with experimental observations
Fatigue of Heavy-Vehicle Engine Materials : Experimental Analysis and Life Estimation by Viktor Norman( Book )

3 editions published in 2015 in English and held by 3 WorldCat member libraries worldwide

On Aortic Blood Flow Simulations Scale-Resolved Image-Based CFD by Jonas Lantz( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

This thesis focuses on modeling and simulation of the blood flow in the aorta, the largest artery in the human body. It is an accepted fact that abnormal biological and mechanical interactions between the blood flow and the vessel wall are involved in the genesis and progression of cardiovascular diseases. The transport of low-density lipoprotein into the wall has been linked to the initiation of atherosclerosis. The mechanical forces acting on the wall can impede the endothelial cell layer function, which normally acts as a barrier to harmful substances. The wall shear stress (WSS) affects endothelial cell function, and is a direct consequence of the flow field; steady laminar flows are generally considered atheroprotective, while the unsteady turbulent flow could contribute to atherogenesis. Quantification of regions with abnormal wall shear stress is therefore vital in order to understand the initiation and progression of atherosclerosis.However, flow forces such as WSS cannot today be measured with significant accuracy using present clinical measurement techniques. Instead, researches rely on image-based computational modeling and simulation. With the aid of advanced mathematical models it is possible to simulate the blood flow, vessel dynamics, and even biochemical reactions, enabling information and insights that are currently unavailable through other techniques. During the cardiac cycle, the normally laminar aortic blood flow can become unstable and undergo transition to turbulence, at least in pathological cases such as coarctation of the aorta where the vessel is locally narrowed. The coarctation results in the formation of a jet with a high velocity, which will create the transition to turbulent flow. The high velocity will also increase the forces on the vessel wall. Turbulence is generally very difficult to model, requiring advanced mathematical models in order to resolve the flow features. As the flow is highly dependent on geometry, patient-specific representations of the in vivo arterial walls are needed, in order to perform an accurate and reliable simulation. Scale-resolving flow simulations were used to compute the WSS on the aortic wall and resolve the turbulent scales in the complex flow field. In addition to WSS, the turbulent flow before and after surgical intervention in an aortic coarctation was assessed. Numerical results were compared to state-of-the-art magnetic resonance imaging measurements. The results agreed very well, suggesting that that the measurement technique is reliable and could be used as a complement to standard clinical procedures when evaluating the outcome of an intervention.The work described in the thesis deals with patient-specific flows, and is, when possible, validated with experimental measurements. The results provide new insights to turbulent aortic flows, and show that image-based computational modeling and simulation are now ready for clinical practice
Essays on manufacturing-related management accounting by Andreas Myrelid( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

In general companies continuously have to improve their operations to be able to survive in the global competition. They have to be better in utilizing their resources today compared to what they were yesterday. The production systems have changed during the 20 th century and factories today do not look like they did hundred years ago. Focus has moved from mass production towards flexibility. The changes in production philosophy have not been followed by a corresponding change in different supporting functions. Research shows that many companies still use accounting methods that have not been developed since the 1930s. The purpose of this licentiate thesis is to provide perspectives on some aspects concerning the relationship between manufacturing operations management and management accounting. This will increase the knowledge and understanding of how management accounting information supports manufacturing decision making. This thesis reports findings from four studies designed to investigate the informational relationship between management accounting and operations management in companies. Results from this research shows that there are many factors to consider when choosing and designing an appropriate management accounting system. Contextual factors include market, manufacturing strategy, technology, and organization. This thesis also reports on the difficulties of making theoretically sound methods work in practice. This thesis contributes with some explanatory aspects on the practical problem and investigates some potential ways forward concerning manufacturing-related management accounting
Thermal and mechanical behaviors of high temperature coatings by Kang Yuan( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

Urban Consolidation Centres : On Relationships between Customer Needs and Services in City Logistics by Henrik Johansson( Book )

3 editions published in 2018 in English and held by 3 WorldCat member libraries worldwide

Urban Consolidation Centres (UCCs) are often conceived as an enabler to alleviate negative effects associated with distribution of goods in cities, such as traffic congestion and hazardous emissions. UCCs not only have the potential to reduce these effects but also provide alternative distribution solutions by introducing new transhipment points. Despite their potential, UCCs often fail to be self-supporting and are often dependent on subsides, which is not considered to be sustainable in the long run. In response, this thesis takes its point of departure in the two business models elements value propositions and target customers. A business model is often viewed as an enabler to generate revenue and UCCs have the potential to generate revenue by offering services to their customers, and the customers pay for the services. To understand how customers can benefit from UCCs and provide arguments why they should use these, it is important to understand the relationship between customers' needs and the services UCCs can provide. The purpose of this thesis is to identify and describe the potential relationship between needs of UCC customers and UCC services. The research in the thesis is both explorative and descriptive, where a first step is to identify customer needs, UCC services, and value propositions. The descriptive part is to describe them and it is also the foundation for understanding the relationship between customer needs and UCC services. Through the analysis and discussion, multiple customer needs are identified and described for seven customer groups and the UCC operator; all of which could be considered customers of UCCs. The thesis also adds to the UCC literature with three new identified UCC services: e-commerce with used products, advertisement, and registration in computer system. The outcome of the analysis also provides illustrations of how customer needs can be matched with UCC services. For the most studied customer group, receiver of goods, a total of 29 different matches were identified, which illustrates the possibilities but also the complexity of the relationships. To understand the relationship, three different types of gaps were also identified that have implications for future research. The main contributions to research and the UCC literature in particular are enlargement of the scope of customers and the illustration of the relationships between customer needs and UCC services. The illustrations include contributions such as identifying, mapping and describing the customer needs, UCC services, and value propositions. An important first step is to understand how customer needs and UCC services can be linked, and this thesis provides examples of how this can be achieved. Viewing every stakeholder as a potential customer opens up the opportunity to fulfil their needs and the potential to generate revenue, which in turn could close the gap in the problem of non-self-supporting UCCs. Furthermore, with self-supporting UCCs, the number of freight vehicles can be reduced and this may lead to more attractive cities with less traffic congestion and lower emissions
Nickel-based single-crystal superalloys : the crystal orientation influence on high temperature properties by Mikael Segersäll( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

Superalloys are a group of materials that are used in high temperature applications, for example gas turbines and aero engines. Gas turbines are most commonly used for power generation, and it is only the very critical components which are exposed to the most severe conditions within the turbine, which are made from superalloy material. Today, energy consumption in many parts of the world is very high and is tending to increase. This implies that all power generating sources, including gas turbines, must aim for higher efficiency. For the gas turbine industry, it is a continuous challenge to develop more energy-efficient turbines. One way to do this is to increase the temperature within the hot stage of the turbine. However, increased temperature in the hot stage also challenges the materials that are used there. Today's materials are already pushed to the limit, i.e. they cannot be exposed to the temperatures which are required to further increase the turbine efficiency. To solve this problem, research which later can lead to better superalloys that can withstand even higher temperatures, has to be conducted within the area of superalloys. The aim of this licentiate thesis is to increase our knowledge about deformation and damage mechanisms that occur in the microstructure in superalloys when they are subjected to high temperatures and loads. This knowledge can later be used when developing new superalloys. In addition, increased knowledge of what is happening within the material when it is exposed to those severe conditions, will facilitate the development of material models. Material models are used for FEM simulations, when trying to predict life times in gas turbine components during the design process. This licentiate thesis is based on results from thermomechanical fatigue (TMF) testing of Ni-based single-crystal superalloys. Results show that the deformation within the microstructure during TMF is localized to several deformation bands. In addition, the deformation mechanisms are mainly twinning and shearing of the microstructure. Results also indicate that TMF cycling seems to influence the creep rate of single-crystal superalloys
Stress and fatigue constrained topology optimization by Erik Holmberg( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

This thesis concerns structural optimization in conceptual design stages, for which constraints that are adapted to industrial requirements have been developed for topology optimization problems. The objective of the project has been to identify and solve problems that today prevent structural optimization from being used in a broader sense in the avionic industry; the main focus has been on stress and fatigue constraints in topology optimization. The thesis consists of two parts. The rst part gives an introduction to topology optimization and describes the developed methods for stress and fatigue constraints. In the second part, two papers are included, where the stress and fatigue constraints are evaluated, respectively. In the rst paper, a clustered approach is presented, where stress constraints are applied to stress clusters, rather than points on the structure. This allows for a trade-o between computational time and accuracy, as the number of clusters and thus constraints can be varied. Dierent approaches for how to sort stress evaluation points into clusters and how to update the clusters, such that the results are suciently accurate for conceptual designs, are developed and evaluated. The two-dimensional examples conrm the theoretical discussions and the designs that are obtained have managed to avoid large stress concentrations, even for problems with an initial stress singularity. Compared to the traditional stiness based designs, the stress constrained designs are considered to be closer to a nal design, which will decrease the total product development time. The second paper uses the methodology developed in the rst paper and applies it to high-cycle fatigue constraints. Using loads described by a variable load spectrum and material data from fatigue tests, the tensile principal stresses are constrained by a limit that is determined such that fatigue failure will not occur. In the examples, where the mass is minimized subjected to fatigue and static stress constraints, simple topologies are obtained and the structural parts are sized with respect to the critical fatigue stress and the yield limit. Stress concentrations are again avoided, for example by the creation of a radius around an internal corner. A comparison between static stress constraints based on the von Mises criterion and the highest tensile principal stresses is given and the examples clearly show the characteristics of the two formulations
Geometry based design automation : applied to aircraft modelling and optimization by Kristian Amadori( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

Product development processes are continuously challenged by demands for increased efficiency. As engineering products become more and more complex, efficient tools and methods for integrated and automated design are needed throughout the development process. Multidisciplinary Design Optimization (MDO) is one promising technique that has the potential to drastically improve concurrent design. MDO frameworks combine several disciplinary models with the aim of gaining a holistic perspective of a system, while capturing the synergies between different subsystems. Among all disciplines, the geometric model is recognized as playing a key role, because it collects most of the data required to any other disciplinary analysis. In the present thesis, methodologies to enable multidisciplinary optimization in early aircraft design phases are studied. In particular, the research aims at putting the CAD geometric model in the loop. This requires the ability to automatically generate or update the geometric model, here referred to as geometry-based design automation. The thesis proposes the use of Knowledge Based Engineering (KBE) techniques to achieve design reuse and automation. In particular, so called High Level CAD templates (HLCts) are suggested to automate geometry generation and updates. HLCts can be compared to parametric LEGO® blocks containing a set of design and analysis parameters. These are produced and stored in libraries, giving engineers or a computer agent the possibility to first topologically select the templates and then modify the shape of each template parametrically. Since parameterization is central to modelling by means of HLCts, a thorough analysis of the subject is also performed. In most of the literature on MDO and KBE two recurring requirements concerning the geometrical model are expressed: the model should be flexible and robust. However, these requirements have never been properly formulated or defined. Hence, in the thesis a mathematical formulation for geometry model robustness and flexibility are proposed. These formulations ultimately allow the performance of geometric models to be precisely measured and compared. Finally, a prototyping and validation process is presented. The aim is to quickly and cost-effectively validate analytical results from an MDO process. The proposed process adopts different manufacturing techniques depending on the size and purpose of the intended prototype. In the last part of the thesis, three application examples are presented. The examples are chosen from research projects that have been carried out at Linköping University and show how the proposed theoretical results have been successfully employed in practice
Sociotechnical system studies of the reduction of greenhouse gas emissions from energy and transport systems by Linda Olsson( Book )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

Public e-Service Stakeholders a study on who matters for public e-service development and implementation by Ida Lindgren( Book )

2 editions published in 2013 in English and held by 2 WorldCat member libraries worldwide

En mängd myndighetstjänster, såsom ansökan om föräldrapenning, finns nu tillgängliga via Internet i form av offentliga e-tjänster. Dessa e-tjänster är tänkta att uppfylla tre generella mål: (1) att förbättra medborgares interaktioner med offentliga organisationer, (2) att effektivisera och förbättra administrativa processer inom den offentliga förvaltningen, samt (3) att öka den offentliga förvaltningens transparens och i förlängningen leda till ett mer demokratiskt samhälle. Arbetet som presenteras i avhandlingen syftar till att identifiera vilka intressenter som påverkar, och/eller påverkas av, utveckling och implementering av offentliga e-tjänster
On Electrohydraulic Pressure Control for Power Steering Applications : Active Steering for Road Vehicles by Alessandro Dell'Amico( Book )

2 editions published in 2016 in English and held by 2 WorldCat member libraries worldwide

 
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Linköping University. Department of Management and Engineering

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English (55)