Simple Construction Lab

In this lab, I built 6 wooden simple structures with the goal of putting them in a controlled environment to test their overall strength and flexibility, and to accurately collect the data from those experiments. To do this we will basically hang weights off of our structures, then incrementally increase that weight, measuring the deflection between each one.

First, I glued 5 matchstick pieces together based on the picture above, with the goal of making them as consistent as possible for the greatest accuracy for when we average our final testing results.

Next I supported each end of the structures as symmetrically as possible by placing them between two level surfaces, with a gap in between them. 

To measure any deflection in the bridge under load, we first need to find our 'zero'. To do this, before any load has been placed on the truss, we will use a height indicator and place the tip as close to the top or bottom as possible. 

Then we set the device to zero. Using this as a reference, we can measure any difference in height  between each load, which would be our deflection.

Next we hang our weights. As you can see I carefully lowered the height indicator between each load to measure how much the structure would bend.

As you can see, due to the incremental weights the simple structures fractured and fell.

Results:

These graphs show the deflection after each increase in weight. Each graph represents an individual structure. On the side you'll notice I included my notes/observations of each individual structure.

Here is the average of all the graphs. With the average max weight being roughly 270 grams, and the average max deflection being roughly 6.8 mm.

Analysis:

Going into this experiment I had a very rudimentary understanding that we were essentially just testing the material involved, in this case being matchsticks. I had no theory other than that the samples would sustain some amount of weight, and eventually bend to a point of fracture or to a point where the span would change due to it bending and touching the sides. Comparing this to the results, there was sometimes where we didn’t get an accurate testing, due to simple glue bond failures, etc., but most of the time we would see the material itself fracture and would receive accurate measurements of the strength of the material/structure.

Conclusion:

In conclusion, in this lab we learned how to create accurate testing environments to precisely test the materials/structures. As well as how to collect and use the data from those tests. Using those skills we tested the materials, and collected semi-accurate results, displayed above, over the course of several different samples. Some of them were only semi-accurate due to glue bond failures, etc., all mentioned above in the notes. Overall, I would say we have a decent average strength of that material/structure, and a general idea of how to improve our testing environment for the future.