2016 – Various – Improvements Utilizing Knitting Technology for Composite Arches – Team 9
Team 9: L to R, Caleb Drake, Eric Marcotte, Ron Bouchard, Nicholas Sluzenski.
The Capstone project will be to investigate knitting technologies as a viable way to increase strength in the Composite Arch Bridge System arches. The braided technology currently being used works well, however one thought is seeing if different shapes can be utilized in arch manufacturing. Our expectation is to manufacture a knitted composite arch made to one-fifth scale. The archs of several configurations will be tested using current ASTM testing standards. The general consensus among all involved, was that our initial goal should be to gain a good understanding of the materials currently being used to build the “Composite Arched Bridge Systems”. We also have been gathering information on knitted technologies, and the composite materials being used. The team is also investigating other composite materials, if it would increase certain properties such as modulus of elasticity, shear stress, or deflection. As with most projects, the scope may change as the project progresses, and will be discussed and agreed upon by all parties. The goal is to complete this project with final comparison data in 22 weeks or May 1, 2016.
We are currently focusing our efforts into researching the current technology used, and learning about composite materials and their different properties. Our focus has also been on knitting vs. woven technologies. The Interim report has been handed in and will be given to Mr. David Erb on 11/13/11 for his review. We will continue researching the knitting machine, and it’s operation. As the project progresses new photos and updates will be added. The first part of the Capstone is centered around research, we intend on troubleshooting the machine once we get a good understanding of what we are trying to accomplish moving forward. The focus of these bridge systems is to reduce the construction time and cost of bridge building, improve the durability and strength of future bridges as compared to aged bridges, reduce carbon footprint of construction and materials, and to progress research in the field of composite structures and materials. Initial knitted carbon composite data will be obtained through coupon testing of resin infused knitted carbon fiber samples produced by the FAK knitting machine. These coupon samples will be produced in accordance to ASTM D3039/D3039M Standards, which outline the accredited testing procedures and requirements to test tensile properties of polymer matrix composite materials.
This week our interim report was forwarded to David Erb for his review. The team will be working with team 8 to order the 1/5 scale braided tubes from A&P Technologies. We will decide on a path after Mr. Erb reviews our reports. Until then we will be working on any questions we have that can be asked at our next meeting. We continue to meet weekly as a team, and with our Capstone advisor Professor Brett Ellis. Log books are kept by each team member and reviewed weekly.
The next progress meeting was on November 18, 2015. At this meeting, the team proposed a rough draft of a defined work scope. We also had more in depth questions about materials, lab access, testing, knitting machine status, and scale factors. David supported the scope presented, focusing on splitting the testing between teams. The coupon and beam testing for one team, and arched testing for the other. After the scope discussion, the focus turned to the FAK machine, material selection, and scale of the project. There are currently 4 different types of drum cylinders that the ASCC has available for use with the FAK machine. The types are classified with the cylinder numbers 260, 220, 120, and 88, with the numbers indicating how many needles are in the cylinders. The FAK machine is currently working, but certain parts, specifically the take-up roller and yarn tensioner, need to be repaired. After being repaired, the FAK-S machine still has its limitations.
Once the correct materials, fabric construction and testing procedures are finalized, the team will move forward with FRP tube production and testing. The tube construction will include knitting, resin infusing and testing for comparison. The goal will be to have eight tubes for comparison. Four straight tubes including two braided and two knitted with one of each filled with concrete. There will be four arched tubes using the same concrete configurations. These straight and arched CFFTs will be tested to the same ASTM standards previously used to test the full scale braided arches. The standards include ASTM D3039 Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials and ASTM C39 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens.
There are more than 350 structurally deficient bridges, representing approximately 15% of all the bridges in the state of Maine. One obstacle to replacing or repairing these structurally deficient bridges involves time and costs. Although braided fiber micro-structures have been successfully employed in CFFTs, alternate fiber micro-structures, such as knitted, have yet to be explored. An analysis of peer-reviewed literature suggests that different fiber micro-structures influence the tensile and bending properties of composites. Knitting is a process of fabric forming by the inter-meshing of loops of yarns. When one loop is drawn through another, loop stitch is formed. Stitches may be formed in horizontal or vertical direction. There are two main forms of knitting, weft knitting and warp knitting. Our finding were compiled into the end of semester report, which goes into more detail about the project, and the expectations moving forward into the next semester.
The second report was reviewed, edited, and forwarded to Mr. David Erb. The team also worked our a preliminary schedule for the next few weeks. The next few items of concern are building a jig for the composite arches along with getting the knitting machine running correctly. The original attempt of knitting E-glass was unsuccessful and always failed due to shear of the material from the sinkers. The E-glass seems to be too thin to knit and will not work with any machine settings attempted
The teams has been busy lining up materials and working to get the knitting machine in the ASCC running smoothly,and operating with the correct tension. A test run was done using the knitting machine, but the yarn was not dense enough and would not knit correctly. The PVA yarn supplied by David Erb has proven to be the most versatile yarn attempted by either team in the FAK knitting machine. We also ordered materials to build a jig for the composite arches, which will be resin infused on the radius of the jig. Since the beginning of the Spring 2016 semester, David Erb and Team 9 member Eric Marcotte have been meeting 2-4 times per week working with the FAK knitting machine. Their time has been spent doing further research with the knitting machine and fine tuning yarns that are currently on hand.
On February 15, 2016, David Erb joined Team 8 and Eric Marcotte to attempt to knit carbon yarn with the 88 needle drum. They were able to successfully able to knit carbon fiber with some defects. Further investigation of the new drum and other carbon yarns will continue.
Everyone has been busy working on different aspects of the project. The knitting machine is up and running with varying results, but things are moving forward. A jig is being made for the one-fifth scale composite tubes to be resin infused on. The goal is to knit tubes out of carbon and e-glass and make both coupons, and tubes for load testing. The interim report three is our focus for the next week. The photo below is how the drum looked after the first few attempts knitting carbon fiber.
Knitting is a process of fabric forming by the inter-meshing of loops of yarns. When one loop is drawn through another, a loop stitch is formed. Stitches may be formed in horizontal or vertical directions. There are two main forms of knitting – weft knitting and warp knitting. The drum has been changed to try and get the knitting machine to run smoother than below using carbon fiber.
The fixture block locations were laid out incrementally along the outer radius. These blocks were attached from the bottom of the plywood with screws going through the plywood and into the blocks. After the nine outer blocks were attached, lines were extended across to the inner radius using a framing square. The inner fixture blocks will be adjustable, with two screws going through the angled aluminum stock and into the adjustable stop. Two pieces of aluminum 90 degree angle stock are then screwed through the aluminum stock and into top side of the plywood approximately four inches from the face of the solid outer blocks, allowing for adjustment of the inner blocks. The adaptability was built into the fixture to account for varying knit CFFT diameters.
At this time, the take up reel assembly is not operational. The rotating shaft that secures the leader cloth and new knitted fabric does not engage. There may be a broken clutch at the bottom of the take up reel . Parts have been ordered and repairs will take place asap. We are also working on sourcing strain gauges, but will wait until we decide on a path for testing. The machine issues have also been a hindrance, but Team 8 and Eric Marcotte have kept working to improve the performance.
David Erb provided Team 8 and Team 9 with sample yarns of cotton and polyester to try knitting. Both yarns are within the denier range of the 88 needle drum but were knitted at the maximum of 6 inches of circumference, which is set by the tension knobs on the machine. The cotton and polyester were thicker than the carbon and required the lowest tension to successfully knit. We were successful in knitting the cotton and polyester yarns and the machine produced very consistent knits.
The take up reel seems to fixed and the 88 drum made a big difference in knitting carbon fiber. There is a lot less fly coming off the needles which allows for a longer knitting time. A vacuum was used to collect the fly from the drum and it extended the allowable run time. More tweaking is needed, but the project seems heading in the right direction.
The scope of the project has been altered. The scope has changed, now with team 8 doing coupon testing, and team 9 will do compression testing on straight round samples. The carbon fiber material is expensive, and our budget would never cover making 1/5 scale arches.The team will do coupon testing and compare values from both braided and knit samples.
The amount of fly coming off the drum requires a vacuum to be held near the head to collect the material to prevent the drum from clogging up. The machine also is being retrofitted with safety guarding.
Today the team successfully knitted a carbon fiber tube for testing. We have a total of around 12 feet so far, and more fiber is being ordered to possibly knit more testing samples. We continue to look for ways to infuse the arch, and believe we have a solution. We will use PVC piping on the inside diameter of the carbon tube, and wrap the tube for infusing using hoses, t-clamps, butyl tape and a bag.
The infusion setup process was started today. Each specimen was wrapped in a mesh to allow the resin to flow while under vacuum of -14.7 psi. Each specimen will then be connected via a hose and inserted into t-clamp. This allows the system to remain under a vacuum, while the resin flows through the mesh. We have our samples all ready to infuse for Monday.
The team has been working on the process of infusing the samples of knitted carbon fiber. Click on the ***”Infusion Process Video***” link below to see the infusing process being completed. Thank you to the ASCC team for assisting us through the process. The next task is to cut the samples so they can be tested, once the specimens cure for 24 hours.
The samples were placed in a chiller for two hours to try and shrink the PVC pipe to allow for the carbon fiber tubes to be removed. The pipes were prepped with a chemical to prevent sticking to the pipe, and worked well. The samples were cut while still on the PVC pipes,using a wet tile saw in the ASCC. The samples were cut to 3.25 inches, then removed from the PVC pipe. Each specimen was then weighed, labeled, and photoed before the start of axial compression testing. Below are of braided, single knit, and double knit samples used in the testing. Note: The braided and double knit carbon fiber samples weighed the same before the infusing process.
The next step is to test the samples using axial compression. We started by using a 10,000N load machine which worked fine for the single braided and single knitted specimens. However, when we tested the double knit specimens, the machine was maxed out. We had to move testing to a load cell which could generate enough force to buckle the double knit samples. The data collected seems to yield some positive results.
Below is the compression data sheet for Derekane 510N vinyl ester resin. All of the specimens were tested for axial compression strength, each load cell exerted enough of a load to buckle the specimens.With the research and testing phases of the Capstone project completed, the team will now focus on the final report, detailing our overall research and test results. Thank you to the Advanced Structure and Composite Center Team for all of your assistance in making our Capstone a success. The team would also like to thank Team 8 for collaborating toward a common goal for our client, the ASCC. While we were unable to manufacture knitted arches for testing, we hope the data collected leads to further investigation into the benefits of knitted composites, which revealed improved axial compression loading over the braided specimens. Below are some of our results, but much more data will be used with the compression load data. The double knit specimen clearly had the most strength of the three specimen types. The data collected will be disclosed in our final report, as well as on Maine Day, May 4th, 2016.
Below is a video of a bridge being built in Pittsfield, along with other projects. Click on the video below to see how the bridges are built, and how this technology could become the norm in small and medium bridge installations. The fact that these bridges need little to no maintenance is an attractive feature to municipalities all over the world.
Team Biographies / LinkedIn Pages (click on names):
Ron returned to college in 2013 to pursue a B.S. degree in Mechanical Engineering Technology after working in manufacturing, and will graduate in May, 2016. In 1993 he graduated from Eastern Maine Community College with an A.A.S. degree in Machine Tool Technology. Ron enjoys Patriots football, old muscle cars, and music. Ron is interested in turbine and aircraft engine manufacturing, with a background in tooling design and CNC machining. Areas of interest includes HVAC Design, Thermodynamic Applications and project research.
Eric is in his third and final year at the University of Maine pursuing his B.S. in Mechanical Engineering Technology. Before transferring to UMaine, Eric received his A.S. in Mechanical Engineering Technology from Springfield Technical Community College with the Class of 2013 in his home state of Massachusetts. His favorite aspects of engineering are 3D CAD and research in fuel cell technology. He is a proud member of ASHRAE but hopes to find a career in the automotive industry designing and testing drivetrains and chassis.
Caleb is in his final year at the University of Maine in Orono pursing a B.S. in Mechanical Engineering Technology with a Minor in Renewable Energy Science & Technology. In his spare time Caleb enjoys skiing, hiking, and watching any of his favorite New England sport teams. Upon graduation in May, 2016 he hopes to pursue a career in the renewable energy field and apply his skills to make the world a cleaner and more efficient place for future generations.
Nicholas is his fourth year of college at the University of Maine pursuing a B.S. in Mecahnical Enginerring Technology. Previously he attended Worcester Polytechnic Institute pursuing a B.S. in Robotics Engineering. In his spare time he likes to play board and video games, read comic books, and watching sci-fi/fantasy/adventure. Upon finishing in December, 2016, he hopes to pursue a career in Engineering and Robotics and try to make sci-fi a reality.
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