Bio-Based Composite Bridges Report
http://jocarrer.files.wordpress.com/2011/12/bio-based-composite-bridges-report.doc
Post 5- Tensile test
The following picture shows the set-up of the testing. The machine will apply a tensile force to our sample until it breaks. The samples are held by grips at the bottom and top. They had to be sanded in the middle part of the samples so that they break somewhere at the middle and not at the grips. We do not want breaks at the grips.
This picture shows a broken sample which is a really good break because it didn’t broke at the grips.
The black thing that you see is an extensometer. It is used to get the displacement of the sample when the tensile force is applied.
Post Cuatro
Remember our composite material with sisal strings from week 2 post. Well, kyle and I had to cut it and make samples to do some tensile testing at the lab. Here is a photo of the samples we cut. These eleven specimen would be tested at failure using the machines at the lab. We have to collect data for three different specimen configuration. Specimen containing 4 sisal strings, 2 sisal strings and no strings at all. The data we are looking for is tensile force at failure, stress, strain, and Young’s modulus. “Strain” is used to measure deformation of the material and “Young’s modulus” is used to describe the stiffness of the material. In summary, the main reason of the testing is to see if sisal strings sandwiched with paper improve the composite material properties. Properties such as strength and stiffness. 
Post tres
The following pictures shows how we did some of the jute burlap testing . Well, it took a lot of sand and steel bars to get the forced required to break the burlap that is why we only did one test. We went back to our original testing, so we have to take jute strings and test them like we did with the sisal strings. We’ ll eventually use burlap as a sandwich composite with recycled paper.
Week2
The second week of work was pretty productive, I got to test more strings but made of jute. The set up was the same as the sisal string testing, the only thing that changed was the material. Finally kyle and I fabricated our first composite material . The following picture shows the set up of the sisal strings with recycled paper before soybean resin was infused. In previous researches recycled paper sheets glued together with soybean resin turned out to be strong. The main purpose of the sisal strings is to make the structure of the sheets of paper even stronger and stiffer.
Figure 4 shows the 10 sheets of recycled paper and sisal strings in the middle of the sheets after the soybean resin (AESO) was infused.
fig 4
Fig 5 and 6 show the composite material after we let it cure over the weekend. Hopefully we get to test this composite material at the lab during week 3.
Fig 5
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Fig 6
Week 1
I am behind on my week 1 post but here it goes. I got to visit many buildings around the Delaware University campus and I really enjoyed. I met the professor who I have to work for my research and he is nice. During the first week I have been reading articles related to my project topic which is Bio-Based Composite Bridges but I also started testing sisal strings in order to calculate the stress (σ) of them.
During our first week of work Kyle (lab partner) and I tested sisal strings in order to calculate their stresses. Stress= F/A where F= force at failure and A= cross sectional area of the material. Stress is the internal resistance of a material to the distorting effects of an external force or load (http://www.engineersedge.com/material_science/stress_definition.htm). Pretty much stress is a way to measure how strong the material is when a force is applied. Fig.1 shows the σ (stress) and the tensional force applied to the block. As you can see a tensional force (F) is applied to the block, we did the same thing with the jute/sisal strings but in our case the tensional force was created by a bucket with sand. The weight of the bucket created a tensional force which we will use to calculate stress. Fig 2 shows the set up of the experiment at the Civil Engineering lab.
Fig 1
Fig 2
The following link http://www.youtube.com/watch?v=cj8cGFziQog is a video recorded by my partner where I am pouring sand in order to find the force that takes to break the sisal string. The stress of the sisal strings are calculated in the following way: σ = weight of the bucket at failure/ cross sectional area of string.
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