Using Tensile Testing Machine
Author: Ross Harper | Major: Industrial Engineering | Semester: Fall 2022
My name is Ross Harper, and I am an industrial engineering major at the University of Arkansas. My mentor’s name is Dr. Haitao Liao with the department of industrial engineering. I conducted research during the Fall semester of 2022. I plan to adapt my research into an honors thesis and graduate in Spring 2023.
My research investigates the effects of various designs on the physical properties of 3D-printed watch bands, including tensile strength, cost, and comfortability. Band length, presence of perforations, and width are some variations in design. Variations are also present in the 3D-printing process, including layer thickness, infill pattern, and infill percentage. My research uses a factorial experimental design to study how combinations of these variations affect the properties of printed bands. Furthermore, using factorial design can shed light on any interactions or correlations that may be present between the factors.
The properties studied for this research are tensile strength, cost, and comfortability. Along with determining how the design factors affect the band properties, this research looks at the best band design that minimizes cost and maximizes strength and comfortability. This research may be helpful in the real-world for aspiring entrepreneurs in the 3D-printing business. 3D-printing is a rapidly growing industry that can serve a large market of consumers. Entrepreneurs may be able to use this research to learn how design variations affect product costs and quality. They will then have more insight into how to create the highest quality products at the lowest cost.
I chose my topic by taking an honors research class given by Dr. Kelly Sullivan, a faculty member of the industrial engineering department. In the class, several members of the industrial engineering faculty spoke to us about their past research and in what fields their research focuses. Dr. Liao’s presentation was very interesting to me because his research combines industrial engineering techniques with hands-on experimentation. I decided to meet with him, and we ultimately decided on my current research topic for exploration.
During this research, I learned that 3D-printed parts can be printed using several factors, including infill pattern, infill percentage, extruder temperature, and print speed. Given the large number of factors and the various settings for each factor, it was apparent that there were nearly an infinite number of combinations to possibly explore. One challenge was that I could not have printed and investigated each of these combinations given the scope of my research. Dr. Liao helped me overcome this challenge by suggesting that I use factorial design, which allows exploration of more combinations than are tested using statistical techniques such as center points.
Another challenge was that 3D-printed parts can be difficult to test, especially with the highly elastic material used in these bands. In initial testing, the bands would slip out of the testing fixtures before any useful data could be collected. This problem was solved by not testing the bands themselves, but instead using a different design that allowed for the part to be stretched properly. I designed this part using a design software and printed several samples using various designs. The new part held up during testing, allowing for data about tensile strength to be collected.
My faculty mentor, Dr. Liao, helped me narrow down the scope of my research to allow for better exploration of the topic. He helped me develop an initial plan for my experimental design and what factors would probably be most important to include. He has also helped me obtain access to a 3D-printing lab, a printer, and printing materials. Dr. Kelly Sullivan was also very helpful in guiding me through the research selection and proposal processes. Dr. Chase Rainwater helped order a new printer and materials to use for my research experiment, along with a new printer extruder when the first one broke. Mr. Mike Kyle in the mechanical engineering department has also been very helpful by allowing me to use a tensile testing machine and demonstrating how to use it.
In the next few weeks, I hope to finalize the analysis of my experiments. I will then use my analysis to adapt this research into a thesis. My research has been a very enlightening experience into how questions about a process or system can be answered using a structured approach.