xpensive wrote:- Round that off to 600 sq.mm area and estimate the force to 4000 N/sin 30, that's just a 13 Mpa compression stress.
- When Aluminium has a modulus of 70 GPa, that's a compression of only 0.10 mm for a 500 mm rod, is that significant?
- A 500 mm Aluminium rod with a 600 sq.mm cross-section would weigh 800 g, how much do you save with carbon fiber?
- As for the buckling force, you need to know the Area moment of inertia, which I have no means of estimating,
but a 55*15 mm rectangular profile, 500 mm long and free at both ends, would take 39 000 N to buckle.
Conclusively: What do you really gain with the carbon fiber rod, stiffness, weight or buckling-strength?
mep wrote:Well if you have in mind that carbon fibre has a modulus of 170-700GPa and a density of 1.85 g/cm³ + very good resistance to corrosion and fatigue then it should be clearly the better material.
However in the may issue of racecar engineering there is article saying that Mclaren has build a full aluminium front wing in 2009!
Also they say that the current wing has a 2-3kg aluminium spar milled from one 160kg solid aluminium block.
Milling away 158kg of aluminium seems to be the absolute waste of material and time for me.
marcush. wrote:but what about compression ? I thoght carbon was not a good thing in terms of compression capabilities..
riff_raff wrote:This discussion of the relative merits of composite vs metal for pushrods is very interesting.
There are some applications where metals can still outperform composites. A good example is the fan blades of large turbofan engines. Rolls-Royce still uses titanium because they can make titanium blades thinner and more aerodynamically efficient than using composite.
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