Examensarbeten för masterexamen // Master Theses
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- PostAnalysis of the Range of Motion of the Shoulder During Static Loading(2004) Holmqvist, Kristian; Martinsson, Jan; Chalmers tekniska högskola / Institutionen för maskin- och fordonssystem; Chalmers University of Technology / Department of Machine and Vehicle SystemsWhen developing new and safer vehicles, crash test dummies are important tools. The crash test dummy used in offset frontal collision tests today (Hybrid III), in e.g. EuroNCAP consumer testing is, to our knowledge, poorly validated for that type of testing. Volvo Car Corporation, Autoliv Research and Chalmers University of Technology have found a need for a tool that more accurately predicts the protective effects of safety systems in real life oblique and offset frontal crashes. This will be solved by designing a more humanlike dummy. The intention is to further develop the crash test dummy, THOR Alpha, to obtain a crash test dummy with more human-like movement in oblique and offset frontal collisions. The crash test dummy shoulder design of today is not very like that of a human. It is our belief that the human shoulder complex will move both superiorly, medially and further anterior than do the shoulder of the Hybrid III and the THOR Alpha dummy. This may influence the kinematics of the dummy when its movement is oblique and/or offset. It also influences the shoulder/belt interaction when using, for example, a three point belt. In order to construct a crash test dummy shoulder with more human-like kinematics there is a great need for information concerning the human shoulder complex. Range of movement and stiffness are especially important properties. In this thesis five volunteers were tested to obtain data on the kinematics and stiffness of human shoulders. Repetitive tests were conducted in a specially built test device in which the volunteer s arms were loaded with up to 40 kg in three directions in the sagittal plane and the displacement of the shoulders were recorded. When loading the shoulders, in any of the three directions, the movement of the shoulder is combined by anterior, medial and superior movement. The results from the tests show similar translation distance in medial and superior direction even though the direction of the force differs by 35. The values obtained on the stiffness of the shoulder in our study are very much dependant on the muscle tonus of the volunteers but it provides a useful estimate. The data acquired in this study will enable improvements to the shoulder of the present dummies which will lead to improved vehicle safety.
- PostFinite Element Rail Vibration Dynamics - Multi-body Dynamics of Modern High-speed Trains(2004) Ching, Chun Yuen; Chalmers tekniska högskola / Institutionen för konstruktionsteknik; Chalmers University of Technology / Department of Structural EngineeringRailway systems have served as a major form of transportation for more than one and a half century. The role of this traditional traffic still remains its importance in spite of by road, water and air traffic. With the advances of technology, trains run faster and faster. Ground vibration problems due to rail vehicle passage have become a concern for the public. Dynamics of rail vehicle is very complicated. Movements of mechanical parts and responses of suspension systems influence the load transferred to the ground. This project is aimed at constructing a multi-body train model for train induced ground borne vibration simulations. The train is modelled in details with car body, bogies, wheels, primary as well as secondary suspension system to obtain realistic load distributions to the rail structure. To analyse different factors concerning ground vibration, three types of high-speed trains: X2000, TGV and ICE are modelled. Results were compared with the early developed box train model . Data obtained suggests maximum amount of vibration occur at about 80m/s. The vibration amplitude is also greatly influenced by the geometry of the train. The movements of the train parts indicate that the train models function as they are supposed to be in the reality. The train models are suitable to be used for studying the effect due to track irregularity, curvature and elevation. It can also be adopted for simulation of ground improvement methods and interaction with other type of structures.
- PostMarginal Production of Pulpwood to the Pulp and Paper Industry(2004) Åström, Stefan; Chalmers tekniska högskola / Institutionen för energiteknik; Chalmers University of Technology / Department of Energy TechnologyThe debate of waste management and recycling is a common element in the discussion on sustainable development. The development of these areas is commonly regulated by governmental policies on recycling rates and other activities. The effects of these policies are often on the margin of the system affected. This study aims at identifying the marginal production of pulpwood that would be affected through the market mechanisms of recovered paper and pulpwood, a mechanism described by Ekvall (2000). By using the method developed by Weidema (1999), the marginal production of pulpwood was identified. Five steps were used for enabling the identification. The steps involved investigation of the market situation and trends, constraints on production changes as well as a review over economic factors. Since the system studied was global, a system limitation was used in order to handle the data collection procedure. Ten different production systems were chosen dependent on natural and social conditions. The result shows that the marginal production of pulpwood originates from industrial plantations of fast-growing forests, for example Eucalyptus, in a region with similar characteristics as Brazil. The effect on this production by a change in Swedish recovery of paper is shown by the cross-price elasticity between recovered paper and woodpulp. The cross-price elasticity indicates that an increase in supply of Swedish pulpwood that corresponds to a 10% decrease in price will induce a 4.5% demand decrease of Ecalyptus pulpwood from Brazil.
- PostSpace-time finite elements and adaptive strategy for the coupled thermoelasticity problem(1999) Larsson, Fredrik; Chalmers tekniska högskola / Institutionen för hållfasthetslära; Chalmers University of Technology / Department of Solid Mechanics