These observations will be combined with predictive models of behaviour to define a lifing philosophy based on crack arrest for rings representative of compressor ring components. The influence of fibre distribution, crack size, crack shape, loading geometry and testpiece size will be addressed in detail. It is the intention of this proposed programme to quantify those conditions under which crack arrest occurs for cracks growing from unbridged defects. They rolled the dice (in an engineered kind of way) and Lewis ended up with double 6 whilst Valtteri and Carlos had their dice fall off the playing table! You can see the highs and lows in the video below.LIFE PREDICTION OF FIBRE REINFORCED TI MMCS UNDER CYCLIC LOADING IN THE PRESENCE OF AN UNBRIDGED DEFECT.ĭominant localised cracks are observed under cyclic loading in fibre reinforced Ti MMCs and their growth can be characterised by fracture mechanics parameters. Is that what happened at Silverstone? Was there a trade-off? I think so, the teams traded certain time lost in the pits for uncertain risk at the end of the race. So the additional weight, the reduction in horsepower, the drop in revs all contributed to the engine lasting longer than a 24 hour race before needing a rebuild. What was the difference between my old BMW M3 race engine and the road going version of the same thing? In reality it was about 100,000 miles. So, what we can see is a trade-off – performance vs life. “Overengineering” or adding in “safety factor”, will make things last longer but at what cost? An overengineered lightbulb with a filament like a coil of barbed wire might last forever but will use electricity way out of proportion to the usefulness of the light it provides. Whereas the Porsche engine that I use in the NMA Course content on this subject, most certainly is not used to failure as it is being used in the WEC series and a non finish because you overused your engine is not going to be popular! In some cases, such as lightbulbs, we use them to failure and the life is actually an expectation of the time it will serve us. Using it after that time or number of cycles increases the probability of failure. This is where Lifing comes in – it doesn’t matter whether it is our racing cars or bridges, planes or lightbulbs each part of each machine or structure has an engineered length of usage time where it is considered to be “safe” within certain limits and boundaries (the operating window). What went wrong then? Did the teams play fast and loose with the cambers again like in 2013? Were the tyres under inflated, like 2013? Or were Pirelli, whilst working to the FIA mandate of spicing up the races, wrong in advising 40 laps life? Was the life less than that in reality and the early pace car allowed the teams to drop in a “cheap” (in terms of time) pitstop that became very expensive (in terms of stress as well as ££s and points) later on? Massive right hand corner speed chews up a left front tyre and when you add those super long high speed right handers even the hardest of tyres are begging for mercy very quickly.Īdd in that these tyres, according to Pirelli, on the television, had a life of 40 laps (I note they are now saying 50 laps to shield themselves from blame, hence the political bit) and the failures were at 37, 38 and 39 laps. We know that carbon fibre shards take no prisoners and will puncture tyres in a heartbeat and, yes, there had been a crash with bits everywhere and Kimi had misplaced a wing, but strangely all the punctures were to the left hand front the most hard working tyre on the Silverstone circuit. Although there were many on the idiot’s lantern (again, check the Urban Dictionary) at the time that talked about debris on the racetrack causing the failures but I’m going to call that political bull…t. The tyre failures at Silverstone in the British Grand Prix last week. The reason I chose this subject will be obvious to any F1 fan.
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