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MMarcus Dissertation Final -OL.pdf (8.17 MB)

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Theory Driven Engineering Model to Predict Ultrasonic Weld Strength of Plastics

Marcus, Miranda
http://orcid.org/0000-0002-6498-1480
http://rave.ohiolink.edu/etdc/view?acc_num=akron1605556381223829

Abstract Details

2020, Doctor of Philosophy, University of Akron, Polymer Engineering.
As plastics are increasingly used for complex and demanding applications, it is critical to reliably create multi-component assemblies with joints that can meet strict strength requirements. Unfortunately, predictive engineering tools that determine the weld strength of polymers are lacking. This deficiency limits innovative design due to the necessity of lengthy development, costing tens to hundreds of thousands of dollars to complete. To alleviate some of this cost and time burden, it is important to find a way for design engineers to predict polymer weld strength. Previous research has focused on individual elements of the weld process and/or simple geometries that are not applicable for commercial development. Additionally, published approaches have not quantitatively accounted for material morphology like crystallinity and polymer chain orientation, both of which have been theorized to have a significant effect on weld strength. Further, in this work it has been established that stress concentration due to the geometry of the polymer flow has significant effect on ultrasonic weld strength, this has not been explored in any of the reviewed literature. The objective of this work was to develop a theory-consistent set of algebraic equations that can be used in engineering development to predict the tensile strength of ultrasonically welded homogenous plastic joints. It was hypothesized that weld strength can be predicted by combining established theoretical models to account for key aspects of ultrasonic welding: • Transfer of ultrasonic vibrations to the joint. • Internal heat generation rate due to ultrasonic vibration. • Intermolecular diffusion of polymer chains across the melt interface. • Effect of the temperature cycle on the crystalline structure • Effect of shear rate during flow on polymer chain orientation • Stress concentration related to extent of flow It was further hypothesized that by repurposing injection mold modeling software to simulate the weld, the temperature and velocity history of the polymer melt can be predicted. This data was integrated into the combined model. The final model showed good consistency with experimental results. In seven of nine fully welded 20 kHz test cases, the predicted weld strength was within one standard deviation of the experimental average.
Erol Sancaktar, PhD (Advisor)
Sadham Jana, PhD (Committee Member)
Ruel McKenzie, PhD (Committee Chair)
Abraham Joy, PhD (Committee Member)
Wieslaw Binienda, PhD (Committee Member)
271 p.
Polymers
plastic welding; polymer welding; ultrasonic welding; weld strength prediction

Recommended Citations

Citations

  • Marcus, M. (2020). Theory Driven Engineering Model to Predict Ultrasonic Weld Strength of Plastics [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605556381223829

    APA Style (7th edition)

  • Marcus, Miranda. Theory Driven Engineering Model to Predict Ultrasonic Weld Strength of Plastics. 2020. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1605556381223829.

    MLA Style (8th edition)

  • Marcus, Miranda. "Theory Driven Engineering Model to Predict Ultrasonic Weld Strength of Plastics." Doctoral dissertation, University of Akron, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605556381223829

    Chicago Manual of Style (17th edition)

akron1605556381223829
278
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This open access ETD is published by University of Akron and OhioLINK.