Reducing fuel consumption is a challenge which demands a reduction of weight of vehicles. This includes replacing cast iron with A356 aluminium alloy for Diesel engine cylinder heads. This alloy is a good candidate because of great casting properties, but cracks appear in the parts before the end of the fatigue lifetime. These cracks are due to the interaction between creep and fatigue which takes place in the cylinder heads.
In this work, a bench test is created in order to test samples on thermal cycles with a high temperature dwell time. The sample geometry is similar to an intervalve bridge, the most susceptible part for cracks in cylinder heads. Many samples are tested, with varying alloy compositions and heat treatments. Experimental results show that the mechanical strain levels reached are low and a complete analysis is not possible without knowing the alloy dilatation coefficient.
A numerical simulation of the bench test has also been performed in order to complement the experimental results and identify improvements. This simulation shows that at the end of one heating, the middle of the sample is under plastic compression and the surface is under elastic tension if there is a geometrical gap between sample and frame. If there is no such a gap, all the sample is under compression.
| Date | 18 Jan 2016 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Philippe Bocher (Supervisor) |
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Russo, H. (Author),
Bocher (Supervisor),
18 Jan 2016Student thesis: Master's thesis › Master in Engineering: Engineering