Journals from Abroad
Journal: Aaron Holmberg, The Swedish Experience
Summer 2008:
UNL IRES-Sweden Program
SICOMP (Swedish Institute of Composites) Research
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Cultural Experience
I would like to think that my cultural experience was a little more significant that the typical engineering student from Nebraska, because my family origin can be traced back to the Nordic region of Europe. James Holmberg, my grandfather, was the last Holmberg to carry on the family name after arriving in the Midwest with his parents from Sweden. Without the opportunity to study in Sweden, I probably would have never known that my name means “the island mountain." I also discovered that our family tradition of holding hands and singing around the Christmas tree is not just an invention implemented by parents to torment the kids with the anticipation of gift opening. It is actually a tradition deeply rooted in Swedish culture. I discovered many families in Sweden still practice this tradition. My stay in Sweden gave me a deeper understanding of the Swedish culture as well as my own.
The working environment was quite different from any other place I have worked before. SICOMP employees were more relaxed compared to any place I have worked in America. This environment enabled the students working at SICOMP to learn a great deal while getting the work accomplished. People were easy to work with, kind and energetic. The lack of a language barrier due to Sweden's extensive knowledge of the English language made life considerably easier. Compared to other cultural experiences I have had, this would rank as one of the better ones because of the cultural immersion I experienced while working and living alongside the Swedish people. I thoroughly enjoyed it and would recommend this program to any student lucky enough to receive this opportunity.
The Purpose of my Research at SICOMP
As fuel prices rise, the demand for more fuel efficient vehicles is becoming prevalent. One way to make a vehicle more efficient is by reducing its weight. Engineers have been exploring ways to reduce the weight of structural components in vehicles and machines without compromising their integrity. Therefore, conventional materials such as steel and plastic are slowly being replaced with materials such as carbon fiber or fiberglass composites. Composite materials are quickly becoming an essential part of many manufactured vehicle components. For example, the engine mounting bracket for Volvos are now being manufactured out of a fiberglass/thermoplastic composite and the fuselage of Boeing's 787 Dreamliner is composed mostly of carbon fiber composites.
Carbon and glass fibers are extremely high strength when a tensile stress is applied but have a relatively low strength in shear or compression. Due to this fact, fiber composites are highly sensitive to the orientation of the fibers relative to the stress direction. For ease of manufacturing composites with directionally oriented fibers, the fiberglass or carbon fibers are commonly woven into a fabric. The formability of these fabrics is essential to prevent strength-reducing wrinkles from occurring during the manufacturing of curved components. Currently the only way to determine if a fabric will wrinkle during fabrication is by a costly trial and error procedure.
Characterization of fiberglass and carbon fiber fabrics would help in predetermining the viability of a fabric for a particular component without laboratory testing. The amount of force needed to displace a unit area of material in shear along with the angle at which this force dramatically increases and wrinkles begin to appear (called the locking angle) are essential characteristics of a fabric needed to determine its formability.
My Experience at SICOMP
 Aaron standing by the drape fixture during preliminary testing.  Solid model of the drape fixture |
After the problem was presented and its relevance explained by Dr. Anders Holmberg, it was determined that a fabric drape fixture needed to be designed and built for the characterization experiments. This task was given to me for the duration of my time at SICOMP. After reading multiple theses about the characterization of fabrics in the textile industry, a plan was devised. Working with the technicians at SICOMP, a solid model of the drape fixture was designed. About three iterations of the design were worked through before the material was ordered from a local machine shop.
While waiting for the material to arrive I was allowed to spend my time in the lab. I volunteered to help perform nondestructive tensile testing of fiberglass composite rods. This was an intriguing experience because I had never heard of, let alone performed nondestructive testing of components with an ultrasonic transducer used to listen for cracks forming as the load was applied.
I was also given the opportunity to work on a personal project in the laboratory while waiting for the fixture material to arrive. After some training, the lab was at my disposal. I worked with many different forms of carbon fiber, fiber glass, kevlar and different manufacturing techniques to obtain the results I desired. Whenever a SICOMP employee was spotted performing some interesting task, I would inquire as to what they were doing. During this time I learned a great deal about composites and how they are manufactured and tested.
Once the material was received for the fixture, all of my time was dedicated to fabricating the parts and assembling them. The fixture was completed just in time for a few preliminary tests before my time at SICOMP came to an end. For the preliminary tests a tensile fiber was attached to the fixture and a load was
incrementally applied via known masses added to a container hung at the end of the fiber. The approximate locking angles of two different fabrics were determined.
The fixture is a good start in the characterization of fabrics used for composite materials. A presentation of the work completed and the knowledge gained was finished and given to Dr. Holmberg after my time at SICOMP was completed. It was a rewarding experience with a great wealth of cultural and technical knowledge gain in a short period of time. I greatly appreciate the opportunity the National Science Foundation has given me through Dr. Allen's work.
