Scholarly Work - Mechanical & Industrial Engineering
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8878
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Item Design of Experiment to Determine the Effect of the Geometric Variables on Tensile Properties of Carbon Fiber Reinforced Polymer Composites(MDPI AG, 2023-05) Janicki, Joseph C.; Egloff, Matthew C.; Bajwa, Dilpreet S.; Amendola, Roberta; Ryan, Cecily A.; Cairns, Douglas S.Carbon fiber reinforced polymers (CFRPs) are increasingly used in the aerospace industry because of their robust mechanical properties and strength to weight ratio. A significant drawback of CFRPs is their resistance to formability when drawing continuous CFRPs into complex shapes as it tends to bridge, resulting in various defects in the final product. However, CFRP made from Stretch Broken Carbon Fiber (SBCF) aims to solve this issue by demonstrating superior formability compared to conventional continuous CFRPs. To study and validate the performance of SBCF, a statistical design of the experiment was conducted using three different types of CFRPs in tow/tape form. Hexcel (Stamford, CT, USA) IM7-G continuous carbon fiber impregnated with Huntsman (The Woodlands, TX, USA) RDM 2019-053 resin system, Hexcel SBCF impregnated with RDM2019-053 resin, and Montana State University manufactured SBCF impregnated with Huntsman RDM 2019-053 resin were tested in a multitude of forming trials and the data were analyzed using a statistical model to evaluate the forming behavior of each fiber type. The results show that for continuous fiber CFRP tows forming, Fmax and Δmax do not show statistical significance based on temperature fluctuations; however, in SBCF CFRP tows forming, Fmax and Δmax is dominated by the temperature and geometry has a low statistical influence on the Fmax. The lower dependence on tool geometry at higher temperatures indicates possibly superior formability of MSU SBCF. Overall findings from this research help define practical testing methods to compare different CFRPs and provide a repeatable approach to creating a statistical model for measuring results from the formability trials.Item Formability Characterization of Fiber Reinforced Polymer Composites Using a Novel Test Method(ASTM International, 2021-10) Janicki, Joseph C.; Egloff, Matthew C.; Amendola, Roberta; Ryan, Cecily A.; Bajwa, Dilpreet S.; Dilpreet S., Alexey; Cairns, Douglas S.Fiber reinforced polymer composites are often used as a replacement for metal alloys because of the superior strength to weight ratio. However, a major drawback of these materials is the lack of formability caused by the low strain to failure ratio that does not allow the material to follow tooling contours into deep drawn shapes or tight radii. Composite materials have a multiscale hierarchical structure where micro and meso scale effects (fiber and tow scales) contribute to the macro structural response (laminate scale). In particular, during forming, different deformation occurs simultaneously at every scale. Currently, the amount of quantifiable and comparable forming data for both continuous and discontinuous fiber reinforced polymer composites, including a multi-scale understanding of the deformation response, is limited because of the lack of a testing system. This article proposes a novel test method and an apparatus called “the forming fixture” for testing the tow formability of fiber reinforced polymer composites by determining the required load to form an uncured resin impregnated fiber tow sample into a stretch drawn profile. Test results from forming of Hexcel (Stamford, CT) IM7-G continuous carbon fiber impregnated with Huntsman (The Woodlands, TX) RDM 2019-053 resin system, in the temperature range of 21°C–121°C, are discussed to demonstrate the use of the proposed apparatus including representative data. Results showed consistency and repeatability, validating the reliability of the novel method. The test aided in defining the forming behavior of the material in real time both visually (e.g. sample failure location) and as forming load versus displacement curves. A novel forming metrics, relating the maximum drawing depth with no failure and the maximum forming load, is defined to compare and select different fiber and resin formulations. Widespread adoption of the forming fixture will reduce reliance on a “trial and error” approach during the the forming process.