## Introduction: Coffee Cup - Honeycomb Sandwich Structure

So you think your coffee is strong? Wait until you have tried your coffee cup!

"A Honeycomb core is an array of hollow columns made of sheet material which is used to separate the two facings of a sandwich structure".

So why not make one of Coffee Cups and enter the Coffee Cup Challenge?

This I'ble will show you how to make a honeycomb panel as a building block for your future projects.  If you like it, don't forget to vote for me!

Note
Where I live, paper cups are somewhat rare, so I have merely made a beam and tested it.
My project has ended by testing this beam. If you want to take it to the next level or if you have an awesome idea, feel free to use this information and even post it in the Coffee Cup Challenge as well (some credits would be nice though).

## Step 1: What Do You Need?

It's a great misconception that you need fancy materials to fabricate composite materials. Nature is full of extraordinary examples.

You will need:
* 45 coffee cups
* two triplex strips of 90 x 20 cm (thickness 2 mm).
* Glue.

The dimension of the strip was more or less determined by the fact that I could only get hold of 45 cups (3 rows of 15 cups).

## Step 2: How It's Made.

1. Apply glue to one side of the first strip (preferably with a brush)
2. Place the cups in an alternating pattern.
3. Apply glue to the second strip and place it on top of the cup.

## Step 3: Testing.

As expected, the beam is very light (900 g).
The test dummy on the picture (me) weighs 80 kg.

Picture 1 & 2
As expected, with pure compression, nothing much happens. Not a crack.

Picture 3
Now it became critical. Upon mounting I could hear some cracks (didn't stay too long on top).

Picture 4
I mounted again with two feet and told the photographer that I would lift my left foot on the count of three. He had to push the button at the same time. The structure collapsed almost immediately.
I was very lucky because: the picture is perfect and I didn't strain my ankle.

## Step 4: Room for Improvement & Applications

I believe you can really make a strong structure with these materials, however there is room for improvement:

1. Arrange the array of cups more neatly (symmetrical).

2. When I applied the glue, I noticed that a lot of it was absorbed by the triplex. Therefore the bond with the cups was likely to be less strong. I neglected this fact.

3. I Added approximately 70 kg of weight where I should have used a vacuum bagging technique. This could have easily increased the "weight" tenfold (700 kg spread evenly). This was a deliberate choice as I wanted to keep the project simple.

4. Some of the coffee cups didn't have a flat surface anymore. Apparently, people often bite in these cups. This reduced the bond as well.

5. In the previous step you can see that one block (on which the beam rested) was slightly higher than the other one, resulting in high local tension probably.

So should we phone NASA and tell them that we have the new building block for their next spacecraft?
It all depends on the confidence that you have in your production process.

Definitely: tables, doors, panels, hatches, shelfs
Probably: light construction elements.
Unlikely: aerospace!

Finalist in the
Coffee Cup Challenge