Metals or Composites?

Has the use of composite materials in aircraft construction peaked?

Peaked?

Who ever stated that it was going to replace it. In ever material that is spec'd, there are trade-offs. Just because composites are new or at least available, does not mean they have to be used.

p911

Fine logic.

GA for you.

There are trade offs indeed.

Inherent advantages of aluminum alloy cannot be denied.

At the same time it is the unique properties of advanced composites made miracle of contemporary civil aircraft design possible.

Each material be it titanium, aluminum alloys, advanced composites or sandwich construction will continue to proper side by side complementing and certainly not at the cost each other.

Composites are much better with respect of strength and stiffness to weight ratio.

But composites lack the inherent lightning protection that is existing in aluminum.

So NASA is searching for this lightning protection: hard nut to crack - have ideas!

RHABE

Hi RHABE, Too stiff wings are a danger!!! Also I would like to point out that just because a material is readily available does not mean that you have to use it for a specific job!!!

Spencer.

Better to choose a material available only in minute quantity in a far an distant land

At surface value, the statement "strength-to-weight ratio makes it a better choice" does not make sense. Generally composites are chosen because composites tend to have higher strength-to-weight ratios than metals while metals are usually more cost effective solutions.

However, there probably was some specific design reason for choosing aluminum over a composite. And there was no statement as to which composite material systems were compared to aluminum. I would guess that cost of the material / manufacturing and possibly some other incidental effect such as additional lightning protection needs for a composite drove the design decision to aluminum. Afterall, there are plenty of aircraft flying around with composite construction. And for aircraft, minimizing weight is critical. Thus if aluminum generally had higher strength-to-weight ratio than composites, and cost less, then no aircraft would be made out of composites. Consequently, there was some other driving factor to use aluminum.

It looks that the decision to over look composite could be due to limited number of aircrafts Mitsubishi expected to sell. Composite tooling, limited shelf life of raw materials and manufacturing are cost intensive and break even can be hoped only with volume production

As for aluminum alloy Mitsubishi is likely to stick to conventional time tested alloys. It will be unlikely to be challenging Al-Li alloys. With 10% lower density and 10% higher strength than conventional aero space 20XX and 70XX al alloys it was touted as material to dominate air craft structures. But as of now Al-Li alloys are confined to space vehicle application where cost is secondary to low density, high specific modulus, excellent fatigue and cryogenic toughness. It is more expensive than composites, titanium and three times the cost of aluminum.

I often find it difficult to understand classification of materials into conventional groupings. Why, because the border has ever increasingly become fuzzier. Composites quite literally mean a combination of more than one material being used. Plywood is a composite! Concrete is a composite. But the question evolves that how small does one item have to be to make it a composite?

Does putting steel fibres into an aluminium matrix make it a composite? Does having interstitial particles in a metal matrix make it a composite? Do alloys count as composites, if the molecules stay separated? Is steel a composite of iron and carbon?

Composites will never become obsolete until a materil is found that exhibits the best of all desired properties for all applications. And until such time we will attempt to enhance the materials that we have by combinging them together to better their properties.

ITs about the Composites a lot cheaper and doesn't rely on a natural resource. i been working with composites for the last 3 years. Steel is ok, but requires more machining.

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Has the use of composite materials in aircraft construction peaked?

No and AL availability hasn't either...