CCT Core Materials & Sandwich Structures

Question 1

What is the primary structural purpose of core material in a sandwich composite panel?

Accepted Answer

Separate face sheets to increase bending stiffness with minimal weight gain

Answer

Core material separates the face sheets, dramatically increasing bending stiffness (I-beam effect) while adding very little weight.

Question 2

Which core material is most commonly used in aerospace structural sandwich panels due to its high strength-to-weight ratio and fire resistance?

Accepted Answer

Nomex aramid honeycomb

Answer

Nomex aramid honeycomb offers excellent strength-to-weight ratio, fire resistance, and low moisture absorption, making it the preferred aerospace core.

Question 3

What is the term for the failure mode in a sandwich panel where the face sheet buckles locally due to insufficient core support?

Accepted Answer

Face sheet wrinkling

Answer

Face sheet wrinkling is a local buckling mode caused by inadequate core density or thickness failing to support the compressive face sheet.

Question 4

What is the 'ribbon direction' of honeycomb core, and why does it matter?

Accepted Answer

The direction in which cells are aligned and bonded; it has the highest shear modulus

Answer

The ribbon direction (L-direction) is where honeycomb cell bonds run, giving the highest shear modulus and strength, so orientation must match design loads.

Question 5

What is the purpose of 'potting compound' used around inserts in composite sandwich panels?

Accepted Answer

To locally fill and solidify the core to distribute insert loads and prevent crushing

Answer

Potting compound fills the core cells around hardware inserts to distribute fastener loads over a larger area and prevent honeycomb crushing under pull-out forces.

CCT - Certified Composite Technician Practice Test

CCT - Certified Composite Technician Practice Test

CCT Core Materials & Sandwich Structures