Detection of Defects and Deterioration in Composite and Non-metallic Materials

This flashcard set covers the manufacturing and in-service defects of composite materials, various non-destructive inspection methods, damage classifications, and deterioration types in plastics.

Delamination

A defect forming on the interface of individual layers within a laminate, often resulting from matrix cracks or impact.

Disbonding

A defect resulting from poor adhesion along the bondline between two elements, which can lead to delamination in adjacent layers.

BVID

Barely Visible Impact Damage; impact damage that is difficult to see and detect during visual inspections.

Liquid Ingression

An in-service problem common to honeycomb structures where fluids enter the internal structure.

Visual Inspection

The primary method for all in-service inspections of composites, used to identify surface defects like scorch, stains, or dents.

Coin Tapping

The most common audible testing technique where a dull or thud sound indicates a defective area, and a clear ringing sound indicates a solid structure.

Ultrasonic Inspection

A method using sound wave energy with a frequency above the audible range to detect internal delaminations and voids.

Radiography

Commonly known as X-ray; an inspection method that records the absorption of rays onto a film to view the interior of a component.

Thermography

An inspection method that uses heat-sensing devices to measure temperature variations and thermal conductivity differentials.

Dye Penetrants

A testing material used on metals but strictly prohibited on composite structures because the wicking action of fibers can absorb the liquid and prevent bonding.

Moisture Meter

A device used to detect water in sandwich honeycomb structures by measuring RF power loss.

Negligible Damage

Damage that can be corrected by a simple repair procedure with no restrictions on flight operations.

Repairable Damage

Damage to the skin, bond, or core that can be repaired but places restrictions on flight operations until the repair is completed.

Non-repairable Damage

Damage to the structure or component that is so severe it cannot be repaired, necessitating replacement.

Cosmetic Defect

A defect on the outer surface skin that does not involve damage to the structural reinforcing fibers.

Environmental Failure (Plastics)

Plastic deterioration caused by factors such as heat, UV rays, microbes, and pollution.

Mechanical Failure (Plastics)

Failure occurring when the impact of an external force is stronger than the yield strength of the plastic material.

Crazing

A plastic defect involving fine cracks on or under the surface, often caused by improper insulation, cold forming, or high localized stresses.

Buffing

The final part of the polishing process used to remove fine, hairline scratches from plastic surfaces.

Stop-drilling

Pratically drilling a small hole with a $1/8\text{ inch}$ ($3.2\text{ mm}$) drill at the extreme ends of a plastic crack to prevent further propagation.