Industri- och materialvetenskap (IMS) // Industrial and Materials Science (IMS)

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Browsar Industri- och materialvetenskap (IMS) // Industrial and Materials Science (IMS) efter Författare "Aalto, Robin"

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    Implementation of a Material Model for Adhesives in Abaqus
    (2022) Aalto, Robin; Käll, Daniel; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Fagerström, Martin; Shetty, Sandeep
    In recent years it has become more common to use adhesive bonded multi-material structures in the automotive industry. These structures are however prone to distortions during the Electrocoat-oven process. These distortions are partly generated due to the curing of the adhesive, in combination with different coefficients of thermal expansion of the materials joined together (Δα). One way to predict these distortions is through FE-simulation. To be able to get accurate results from FE-simulations, a material model that accurately describes the degree of cure and its impact on the mechanical behaviour is required. Volvo Cars is therefore part of the research project MADBOND, in which a material model for adhesives has been developed and implemented in the FE-solver LS-DYNA. In this master’s thesis, the adhesive material model developed in the MADBOND project has been implemented as a user material model in the FE-solver Abaqus, which is the preferred solver for Δα-simulations at Volvo Cars. The Abaqus implementation was evaluated against both the existing implementation in LS-DYNA and a physical test. In the evaluation, the results from Abaqus were within the defined error tolerance of 10% for the residual stresses and residual deformations, when compared to LS-DYNA. In the comparison with the physical test, the same buckling behaviour was noted in the results from both the Abaqus simulation and the test. Significant differences in the magnitudes of the residual displacements was however seen, which in some regions was 10 times larger in the test case. The differences were to a large extent explained by adhesive failure in the test, which was an aspect not included in the simulation model. A convergence study was conducted for the material model, and it showed that the time increment size had a significant impact on the results, both in LS-DYNA and Abaqus. It was also discovered that the Abaqus implementation was not compatible with parallel execution. It was therefore recommended that these aspects are taken into consideration in any future work at Volvo Cars in order to perform accurate Δα-simulations for large structures.
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    Utveckling av elektrisk drivlina till klassisk sportbil
    (2020) Aalto, Robin; Hildor, Nils; Johansson, Ludvig; Schmidt, Daniel; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Hulthén, Erik; Evertsson, Magnus
    In todays society questions regarding climate change is an often discussed matter, where the current fleet of cars and whether its emissions can be reduced is a big part of it. Many newly produced cars are electric and in time they are to replace the current cars powered by traditional fossil fuels. The question is how this would work out for car enthusiasts, whose cars maybe are non-replaceable to them. One way of dealing with this would be to change the powertrain itself, keeping the car looking and feeling as original as possible, and by this reduce the emissions while still keeping their cars. This bachelor thesis is written by four students at Chalmers University of Technology and aim to touch this very problem. The main intention is to explore whether a classic sportscar can be converted to run on electricity only. As object of investigation an AC Cobra is used to represent the car, and the goal is to present a theoretically working electric powertrain with the most important components for the car. The work consists of three main parts, where the first part aims to gather information on the original powertrain of the car, the market and the group of target - the car enthusiasts. By finding the specifications of the car and the demands by the enthusiasts, this information can be put together into a list of requirements for the electric powertrain. The second part of the project consists of finding and putting together suitable components for the powertrain, creating several different concepts to evaluate. By first defining what components go into a powertrain generally, it becomes clear what to work with and not. The final part aims to test the different concepts of powertrains by simulating them. They are tested for performance and range, to find out whether or not they can keep up with the requirements set by the original car and the enthusiasts. The results of the simulations are the results of the thesis. The results shows good potential in making an electric powertrain work in the AC Cobra. There are many concepts reaching the performance related demands of a 0-100 km/h acceleration in under 4.2 seconds, a max speed of at least 220 km/h and a range more than 200 km. To have several different concepts reaching the goals also means that different components can be used in different ways best suited for each enthusiast, and they can still get a good result. The electric powertrain is quite expensive at around 250 000 - 350 000 kronor, a bit more expensive than what the group of target is willing to pay. Many demands and different requirements have not been discussed in detail because of the projects limitations. One of this limitations is not building a prototype which means that the results can not be verified to work in the real world. In addition, there has been no calculations on the strength of the componets used, to see if they will hold or not. With the limitations in mind the projects should be seen as a starting point in the question of matter, but not a complete work. There are parts missing that must be filled in if further developing the work to create a more comprehensive proposition of the drivetrain. This being said, the work shows interesting aspects and a promising result for enthusiasts wanting to work towards a greener future.