A selection of images of the products of electrospinning of polymer fibers at CAPE.
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New Website in 2012
The South Dakota School of Mines and Technology will be launching a revised version of the school website in early 2012. We plan on taking advantage of the new look and functionality of the school site in continuing to provide a peek into our activities here at CAPE.
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Flexure Testing of Fiberglass Panels
I have been creating various fiberglass panels that will be subject to impact, flexural, and tensile tests. My previous post shows impact test results and how we define failure for that specific test. This post will summarize the flexural testing done on the same control samples.
The flexure test required the use of the 100kN MTS Load Frame. I used the 3 point bend test apparatus which is shown below. The test simply exerts a compressive force that causes the specimen to bend until it fails.
Shown below are all the specimens that were tested. The longer samples are made to ASTM standard, therefore they will be more useful when compared to the other forms of fiberglass. The smaller specimens averaged a flexural strength of 530 MPa while the larger specimens averaged 430 MPa. This shows that geometry does effect the results in flexural testing.
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Machine Tool Process Design
This is our Vertical Machining Center. We do most of our machining with this. This operates with three axes. The table moves in the X and Y axis. The spindle rotates various cutting tools to cut the material and moves in the Z axis. The combination of the motion of these axes and a cutting tool can form custom parts and assemblies as required by the cutting edge research.
The following shows the steps involved in making a part from start to finish.
SolidWorks is used to take an idea or concept and form it into a to-scale 3D model. The model helps communicate design and is the first step in the process of using computer aided machining to create code for the machine to follow.
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Extremophile Bacteria
I am currently researching Geobacillus and Bacillus bacteria. We are looking into the exopolysaccharide (EPS) production from these types of bacteria. Initial tests need to be done to determine the best nutrient-rich growth medium for the bacteria. Testing methods that will be used for determining different EPS properties will include: GCMS, IR, UV Vis, NMR, SEM, XRD, DMA, and DSC.
Update 9-29-11:
Two medias were prepared: BD Difco Nutrient Broth (NB) and US Biological L-Broth (Luria Broth) (LB). The Difco Nutrient Broth is a general purpose medium for the cultivation of microorganisms with non-exacting nutritional requirements. The US Biological L-Broth is a rich media base for propagation of Escherichia coli that have a low salt content. The purpose of l-broth is for strain maintenance, cloning, plasmid propagation, and protein expression. L-Broth is used in application for the preparation of plasmid DNA and recombinant proteins. The L-Broth media is a nutrient-rich formulation that provides peptide and peptones, vitamins, and trace elements.
After preparing the media, culture growth occurred in the autoclave for 72 hours at 60 C and 100 rpm, the solutions were mixed with trichloroacetic acid and centrifuged to remove the proteins present. The decanted liquid was then mixed with acetone to allow EPS precipitates to form overnight. The acetone mixture was then centrifuged to remove the EPS precipitates.
The first set of EPS precipitates have been produced and are ready for testing. Only the LB media produced EPS precipitates; all NB mixtures were discarded.
The next batch is currently being produced; however, no testing has yet been conducted.
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Gardner Impact Testing of Fiberglass Panels: Failure?
When observing failure in any test we must ask ourselves what actually qualifies as failure in a specimen. Interpretation of failure can vary by material and perspective. Failure can include forms of crack propagation, fully puncturing a panel, and even complete shattering of a specimen. It is up to us as researchers to decide what constitutes failure based on the information we are seeking.
Currently, I am creating various fiberglass panels in which impact testing is involved. Gardner Impact testing is used to find the energy required to bring a rigid plastic specimen to failure. Since we are testing different variations of fiberglass panels, we chose failure to be the point where cracking at 0 and 90 degrees can be seen clearly on the panels.
This image shows cracking at 0 and 90 degrees. As the energy is increased, the cracking increases along with some puncturing of the fiberglass layers. These are all examples of failure.
The above image shows how we arrived at the point of failure. We found that an energy of 11.5 Joules was needed to achieve this.
All impact testing was performed using the Instron CEAST 9350 Droptower. Images of the machine can be seen in a previous post.
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Strain Measurements of Unidirectional CFC in Bending
A number of unidirectional carbon fiber composites were subjected to bending-to-failure while strain was measured on both sides of the centerpoint of the bend. High speed video was also captured as the samples were tested via a modified compression trial.
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Brain Mold
I was tasked with creating a two-part hinged fiberglass mold of a human brain. The brain model used came from an ABS plastic prototype created by the Stratasys 3D Printer. Mold making is a tedious process where science and art meet.
