ACS Composite Materials & Repair 2

Question 1

What is the primary purpose of a peel ply in composite layup?

Accepted Answer

To provide a sacrificial surface layer that creates a bondable texture when removed

Answer

Peel ply is a woven fabric applied as the last layer during layup; when peeled off after cure it leaves a clean, textured surface ready for secondary bonding.

Question 2

Which type of damage to a composite structure is MOST difficult to detect visually?

Accepted Answer

Delamination beneath an intact surface skin

Answer

Delamination (separation of plies) can exist beneath an undamaged-looking outer skin and requires tap testing or NDI methods to detect.

Question 3

During a tap test on a composite panel, a dull or hollow sound compared to surrounding areas indicates:

Accepted Answer

A subsurface void, delamination, or disbond

Answer

A dull or dead sound during tap testing indicates a loss of bond or internal void, while a solid ringing sound indicates good laminate integrity.

Question 4

What is the correct fiber orientation for a quasi-isotropic composite layup?

Accepted Answer

Plies at 0°, +45°, -45°, and 90°

Answer

A quasi-isotropic layup uses plies at 0°, +45°, -45°, and 90° to provide approximately equal stiffness and strength in all in-plane directions.

Question 5

When performing a scarf repair on a composite laminate, the scarf ratio is typically expressed as:

Accepted Answer

Horizontal taper length divided by the laminate thickness

Answer

Scarf ratio is the ratio of the taper length to the laminate thickness (e.g., 20:1 means 20 mm of taper per 1 mm of thickness), determining how gradually load is transferred.

(ACS) Airman Certification Standard Certified Mechanic Practice Test

(ACS) Airman Certification Standard Certified Mechanic Practice Test

ACS Composite Materials & Repair 2