Composite Structures

Question 1

Benefits of composites:

Answer 1

Lighter weight.
Stronger.
More rigid.
Better able to withstand sonic vibrations.

Question 2

Basic categories of composite materials:

Answer 2

Reinforcing materials.
Matrix materials.

Question 3

Types of reinforcing materials:

Answer 3

Fiber glass. (S-glass and E-glass)
Kevlar.
Graphite/Carbon.
Ceramic.
Boron.

Question 4

The major fibers in unidirectional fabric:

Answer 4

Warp threads.

Question 5

The small cross threads in unidirectional fabric:

Answer 5

Fill threads

Question 6

Basic types of resins used in aircraft construction:

Answer 6

Thermosetting.
Thermoplastic.

Question 7

Basic types of thermosetting resins:

Answer 7

Epoxy resins.
Polyester resins.

Question 8

T\F
Epoxy resin curing requires a smaller amount of catalyst than polyester resins.

Answer 8

False.
Epoxy resins use much more catalyst.

Question 9

What prevents prepreg from curing before use?

Answer 9

Refrigeration.

Question 10

Purpose of the matrix:

Answer 10

Binds reinforcing material (laminates) together and transfers stresses into them.

Question 11

Most matrix material are in the form of ______.

Answer 11

Resins.

Question 12

Basic types of foam:

Answer 12

Styrofoam.
Urethane foam.

Question 13

What is used to cut styrofoam?

Answer 13

A hot wire.

Question 14

What important factors must be considered when replacing a piece of honeycomb?

Answer 14

Use same cell size and ensure that the “ribbon direction” of the new piece matches that of the damaged area.

Question 15

_______ is/are used to add body to resins.

Answer 15

Micro balloons

Question 16

Methods of delamination detection:

Answer 16

Coin tap.
Ultrasonic.
Backlighting.
Acoustic emission monitoring.
X-ray.

Question 17

What testing methods are used to detect water in a honeycomb?

Answer 17

X-ray.
Backlighting.

Question 18

What type of drill is used on Kevlar?

Answer 18

Brad point drills.

Question 19

What type of drill is used on graphite material?

Answer 19

Spade drill.

Question 20

Tiny hair like cracks in windows and windshields:

Answer 20

Crazing

Question 21

What determines the strength of a composite structure?

Answer 21

Fiber orientation.

Question 22

Term for layers of composites:

Answer 22

Laminate.

Question 23

The stretch diagonal to the thread direction is called ____.

Answer 23

Bias

Question 24

Define shelf life:

Answer 24

The expiration date of the material.

Question 25

The time that a resin is usable after being mixed:

Answer 25

Pot life.

Question 26

What is the dwell time?

Answer 26

(Cure time) the post application wait time.

Question 27

Types of fillers:

Answer 27

Chopped fibers (Flox)
Micro balloons.

Question 28

What type of filler adds strength to the repair?

Answer 28

Flox. (Chopped fibers)

Question 29

Two ways to prep the repair area for matrix filler:

Answer 29

Scarfing (sanding to a taper).
Step cut.

Question 30

Order of laying the plies:

Answer 30

Filler ply>
Repair ply>
Sanding ply.

Question 31

Methods of curing:

Answer 31

Room temp cure/wet lay out.
Heat bond.