Composite Aerospace Structures Questions and Answers

Answer: C

Both statements are true and the second is the reason for the first. The practical difficulty is that a weak bond is very hard to detect, which is why critical bonded joints frequently carry fasteners as a secondary path.

Answer: D

The assertion is false and the reason is true. Composites are far less fatigue-sensitive than metals in tension, but matrix cracking, delamination growth and, above all, damage from impact all accumulate. Immunity overstates a genuine advantage into an error.

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason is the whole of it. All the reinforcement lies in the plane of the plies, so through the thickness the only thing holding the laminate together is the matrix and the interface. That is why delamination is the characteristic composite failure, why impact is so damaging, and why through-thickness reinforcement such as stitching or z-pinning is pursued.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 give the two rules correctly - the direct rule of mixtures along the fibres, the inverse rule across them. Statement 3 is the opposite of the truth: for a typical carbon-epoxy the ratio is something like sixteen to one, and it is precisely that anisotropy which makes layup design worth doing.

Answer: C

The first two are correct and are separate requirements. The third confuses them: symmetry concerns position through the thickness while balance concerns ply angles, and a laminate can readily be one without the other.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 describe the design consequence correctly: barely visible impact damage cuts compressive strength substantially, and allowables assume it may be present and undetected. Statement 3 is what makes the problem serious - a dropped tool can delaminate the interior while leaving a surface mark that inspection will not reliably find.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: a composite cannot yield locally to redistribute load between fasteners as a metal does, so bolt load sharing must be designed rather than assumed, and a bonded joint transfers load without drilling through the fibres. Statement 3 is wrong - a bond line is far harder to inspect than a bolted joint, and that difficulty is the chief obstacle to using bonds in primary structure.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: moisture plasticises the matrix and temperature compounds the effect. Statement 3 is wrong, and the distinction matters for design. Fibre-dominated properties such as longitudinal tensile strength are barely affected, so the hot-wet knock-down bears on compression, shear and bearing rather than on tension along the fibres.

Answer: C

Correct answer: 1 and 2 only

Statements 1 and 2 are correct. Statement 3 has the galvanic couple the wrong way round: carbon is the more noble of the pair, so it is protected and the aluminium is the one that corrodes. Getting the direction right matters, because it tells you which member needs the protection and which will be found pitted at inspection.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: prepreg arrives with its resin content already fixed, giving close control of fibre volume fraction, and the autoclave applies heat and external pressure together to consolidate the laminate and drive out voids. Statement 3 is wrong - prepreg has a limited out-life and must be kept frozen, since the resin continues to advance slowly at room temperature.