Sandwich cross sections

Last week we tested the capacity of a honeycomb sandwich to take impact energy up, and analysed how flax fibers keep the damaged laminate together preventing splintering.

Yesterday, I decided to make a cross section of the impact site to get a better picture:

P1070238_mP1070239_m

Two things are worth remarking:

  • as expected, most impact energy is absoved by the honeycomb core: The cells got crushed and absorved much of the energy by plastic deformation. Cell deformation extends about two to three cells beyond the recognizable external damage.
  • Though the saw was new and sharp, the edge is fluffly exposing mainly flax fibers. This shows that these fibers have a high impact resistance and a high energy absorption capacity. Properties similar to aramid.

Just for reference, here’s a picture of a broken carbon sandwich (bending failure):

P1070241_m

The edge is clean and sharp, and a cut-out of this sandwich has a perfectly clean edge.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s