<p>During braking, both the rotor and the pads in disc brakes are worn. Since disc brakes are not sealed, some of the wear particles generated can become airborne. Several studies have found an association between adverse health effects and the concentration of particles in the atmosphere, so it is of interest to improve our knowledge of the airborne wear particles generated by disc brakes. However, in field tests it is difficult to distinguish these particles from others in the surrounding environment, so it may be preferable to use laboratory test stands and/or simulation models to study the amount of airborne wear particles generated.</p><p>This thesis deals with a simulation methodology for prediction of airborne wear particles from disc brakes and three experimental methods for testing disc brake materials with focus on airborne wear particles. The four appended papers discuss the possibility to both measure and predict the number and size distribution of airborne wear particles that originate from the pad to rotor contact. The objective is to develop a simulation methodology that predicts the number and size distribution of airborne wear particles from disc brakes.</p><p>Paper <strong>A</strong> describes how a modified pin-on-disc machine was used to study airborne wear particles originating from different disc brake materials. The results indicate that the test setup can be used to measure and rank the number concentration and size distribution of the airborne wear particles generated.</p><p>Paper <strong>B</strong> describes a disc brake assembly test stand for measurements of airborne wear particles from disc brakes. The results indicate that the test setup can be used to measure the number concentration and size distribution of airborne wear particles generated from disc brake materials. The results also indicate a promising ability to rank different pad/rotor material combinations with respect to the number concentration of airborne wear particles.</p><p>Paper <strong>C</strong> compares measurements made in passenger car field tests with measurements made in a disc brake assembly test stand and in a pin-on-disc machine. A promising correlation between the three different test methods is found.</p><p>Paper <strong>D</strong> presents a simulation methodology for predicting the number and size distribution of airborne wear particles using finite element analysis (FEA). The simulated number distribution is compared with experimental measurements at component level. The result indicates that the proposed methodology may be used to predict the number concentration and size distribution of airborne particles generated in the pad-to-rotor contact.</p>

<p>Mechatronics development requires the close collaboration of various specialist teams and engineering disciplines. Developers from the different disciplines use domain-specific tools to specify and analyse the system of interest. This leads to different views of the system, each targeting a specific audience, using that audience’s familiar language, and concentrating on that audience’s concerns. Successful system development requires that the views of all developers produced by the different tools are well integrated into a whole, reducing any risks of inconsistencies and conflicts in the design information specified.</p><p>This thesis discusses techniques of managing and integrating the views from various disciplines, taking better advantage of multidisciplinary, model-based, development. A Model Data Management (MDM) platform that generically manages models from the various domain-specific tools used in development is presented. The platform is viewed as a unification of the management functionalities typically provided by the discipline-specific PDM and SCM systems. The unification is achieved by unifying the kind of objects it manages – models. View integration is considered as an integral functionality of this platform.</p><p>In demonstrating the platform’s feasibility, a generic version management functionality of models is implemented. In addition, model integration is investigated for the allocation of system functions onto the implementing hardware architecture. The proposed approach promotes the independent development of the views, allowing developers from each discipline to work concurrently, yet ensuring the completeness, correctness and analysis of any inter-view design decisions made.</p><p>The prototype MDM platform builds on existing technologies from each of the mechanical and software disciplines. The proposed MDM system is built based on a configurable PDM system, given its maturity and ability to manage model contents appropriately. At the same time, the version control functionality borrows ideas from the fine-grained version control algorithms in the software discipline.</p><p>The platform is argued to be feasible given the move towards model-based development in software engineering, bringing the discipline’s needs closer to those of the hardware discipline. This leads the way for an easier and more effective integrated management platform satisfying the needs of both disciplines using a common set of mechanisms.</p>

<p>The focus of environmental work in manufacturing companies has increasingly shifted from end-of-pipe solutions to the environmental performance of products and services. The product development process is central to creating value for customers. This thesis argues that companies can simultaneously create value for consumers and be profitable while taking environmental considerations into account.</p><p>Modernising ecodesign means taking advantage of environmental benefits and the innovation potential when developing solutions rather than using ecodesign simply to ensure that legal requirements or customer demands are met. Ecodesign is a strategic issue and should be included in early product development activities, such as for project selection and when setting product targets. There is also need to perform ecodesign according to the characteristics of specific development processes as for radical product development or when developing integrated solutions, using a combination of services and products.</p><p>This thesis reports on the findings from five different research studies, all of which adopted a qualitative approach in which the emphasis falls on exploring and creating understanding and meaning. The studies focused on three areas of ecodesign: A) rethinking approaches for manufacturing companies, B) setting environmental project targets and project selection and C) redesign of products.</p><p>Recommendations on how to modernise ecodesign have been developed and can be summarised in six points:</p><p>• Perform ecodesign both vertically and horizontally in a company.</p><p>• Increase interaction between organisational units.</p><p>• Take advantage of innovation potential in products, services, user behaviour and the delivery and take-back systems.</p><p>• Take environmental considerations into account in the project selection process.</p><p>• Set environmental targets for ensuring that environmental considerations are taken when developing innovative solutions.</p><p>• Develop ecodesign procedures that fit the characteristics of the development process</p>

<p>Several fatigue criteria were evaluated with experimental fatigue test data. The fatigue tests contained many different geometries with different degrees of stress concentration. It was concluded that the differences between the criteria were neglectable when compared to the differences between the specimens. The stress concentrations with the stress gradients and sizes of the highly stresses volumes that resulted were very important. In order to understand this, gradient and volume methods were investigated. The gradient methods showed some improvement over the strictly local evaluation first attempted. The volume method, a weakest link application with a Weibull distribution of the fatigue strength, yielded results useable for actual design situations. The volume method is strongly recommended and the choice of criterion does not seem to be very important.</p>

<p>This licentiate thesis is generally concerned with the ductile failure and rupture mechanisms encountered under combined tension and torsion loading. In the first part entitled Paper A, an experimental investigation of the rupture mechanisms in a mid-strength and a high strength steel was conducted employing a novel test configuration. The specimen used was a double notched tube specimen loaded in combined tension and torsion at a fixed ratio. The effective plastic strain, the stress triaxiality and the Lode parameter was determined in the centre of the notch at failure. Scanning electron microscopy of the fractured surfaces revealed two distinctively different ductile rupture mechanisms depending on the stress state. At high stress triaxiality the fractured surfaces were covered with large and deep dimples, suggesting that growth and internal necking of voids being the governing rupture mechanism. At low triaxiality it was found that the fractured surfaces were covered with elongated small shear dimples, suggesting internal void shearing being the governing rupture mechanism. In the fractured surfaces of the high-strength steel, regions with quasi-cleavage were also observed. The transition from the internal necking mechanism to the internal shearing mechanism was accompanied by a significant drop in ductility.</p><p>In the second part entitled Paper B, a micromechanics model based on the theoretical framework of plastic localization into a band introduced by Rice is developed. The model employed consists of a planar band with a square array of equally sized cells, with a spherical void located in the centre of each cell. The periodic arrangement of the cells allows the study of a single unit cell for which fully periodic boundary conditions are applied. The micromechanics model is applied to analyze failure by ductile rupture in experiments on double notched tube specimens subjected to combined tension and torsion carried out by the present authors. The stress state is characterized in terms of the stress triaxiality and the Lode parameter. Two rupture mechanisms can be identified, void coalescence by internal necking at high triaxiality and void coalescence by internal shearing at low triaxiality. For the internal necking mechanism, failure is assumed to occur when the deformation localizes into a planar band and is closely associated with extensive void growth. For the internal shearing mechanism, a simple criterion based on the attainment of a critical value of shear deformation is utilized. The two failure criteria capture the transition between the two rupture mechanisms successfully and are in good agreement with the experimental result.</p>

<p>This licentiate thesis concerns one dimensional flow simulation of turbocharged spark ignited engines. The objective has been to contribute to the improvement of turbocharged SI engines’ performance as well as 1 D simulation capabilities.</p><p>Turbocharged engines suffer from poor gas exchange due to the high exhaust pressure created by the turbine. This results in power loss as well as high levels of residual gas, which makes the engine more prone to knock.</p><p>This thesis presents an alternative gas exchange concept, with the aim of removing the high exhaust pressure during the critical periods. This is done by splitting the two exhaust ports into two separate exhaust manifolds.</p><p>The alternative gas exchange study was performed by measurements as well as 1-D simulations. The link between measurements and simulations is very strong, and will be discussed in this thesis.</p><p>As mentioned, turbocharged engines are prone to knock. Hence, finding a method to model knock in 1-D engine simulations would improve the simulation capabilities. In this thesis a 0-D knock model, coupled to the 1-D engine model, is presented</p>

<p>Paper A: In this paper, the development and implementation of a contact algorithm based on C2-continuous surface representations is discussed. In 3D contact simulations involving models with arbitrarily curved surfaces (as in the case of vessel walls), the discretization of the contact surfaces by means of facet-based techniques could lead to numerical instabilities and finally loss of quadratic convergence. These instabilities arise mainly due to the sliding of contractor (slave) nodes over the boundaries of target (master) contact facets, where jumps of the normal vector are experienced. The paper addresses successfully this problem, by discretization of the target surfaces by means of C2-continuous parameterization schemes. Initially, the uniform cubic B-spline surfaces are introduced. Next, in an attempt for more accurate representations of the geometric models of the contact surfaces, a new parameterization based on the expression of cubic B-splines is developed. The two approaches are implemented into a finite element framework and more specifically, into the multipurpose finite element analysis program FEAP. The special merits of the developed algorithms and the advantages of the smooth surfaces over facet-based approaches are exhibited through a classical contact mechanics problem, considering incompressibility, finite deformations and large slidings. Next, a simulation of balloon angioplasty with stenting is presented, where the contact between both medical devices (balloon and stent) with the arterial wall is modeled. The arterial wall is modeled in this first approach, as hyperelastic, homogeneous, isotropic, while a cylindrically orthotropic model is developed to capture the nonlinear, anisotropic behavior of the balloon catheter under pressure. Two stents with the same geometry but different strut thickness, are studied. Both are considered elasto-plastic. The performed simulations point out the outcome of the balloon angioplasty and stenting in terms of luminal gain and mechanical strains. Finally, a comparison between the two stent configurations is presented.</p><p>Paper B: The second paper makes use of the contact tool developed in Paper A and focuses on the changes of the mechanical environment of the arterial wall due to stenting, as a function of a set of stent design parameters. In particular, Paper B presents a detailed geometric and material model of a postmortem human iliac artery, composed by distinct tissue components, each associated with specific mechanical properties. The constitutive formulation for the artery considers anisotropic, highly nonlinear mechanical characteristics under supraphysiological loadings. The material and structural parameters of the arterial model are obtained through uniaxial tensile tests on stripes extracted from the several arterial tissues that form the stenosis, axially and circumferentially oriented. Through cooperation with a well-established stent manufacturing company, an iliac stent was acquired. The dimensions of the stent are measured under a reflected-light microscope, while it is parameterized in such a way as to enable new designs to be simply generated through variations of its geometric parameters. The 3D balloon-stent-artery interaction is simulated by making use of the smooth contact surfaces with C2-continuity, as previously mentioned. Next, scalar quantities attempt to characterize the arterial wall changes after stenting, in form of contact forces induced by the stent struts, stresses within the individual components and luminal change. These numerically derived quantities allow the determination of the most appropriate stent configuration for an individual stenosis. Therefore, the proposed methodology has the potential to provide a scientific basis for optimizing treatment procedures, stent material and geometries on a patient-specific level.</p>

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<p>Due to different engineering background and limited technical prerequisites, trade-offs are needed when managing information in complex product development. The challenges faced with information management for complex product development are as much of organizational as technical character.</p><p>Information management has in this thesis been analyzed from both a technical and organizational dimension in order to obtain an integrated view and holistic understanding. The technical dimension focuses on information management systems, such as product lifecycle management systems. An information management system in itself does not solve problems in an organization; it manages at its best all types of business data while storing and retrieving information. In order to succeed, information management needs to be aligned with different needs and with a variety of domain-specific work procedures. The organizational dimension includes organizational structures, work procedures, and the designer and management perspectives on needs and benefits with information management.</p><p>Perceived benefits with integrated information management are identified as support for SE, work procedure mapping, use of disciplinary support tools, and data integrity and availability. Five technical and organizational key success factors for efficient information management are presented; usability, integration of information, motivation, information structure and organizational support. It is concluded that structured information, management support and motivation among designers are more important than customization of information management systems in order to achieve integrated information management.</p>