Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 99903

99903 - Asymmetrically Tough Composites 

Constructing new composites has continued to be a focus of materials and mechanical engineering. New composites have had ramifications for several industries, including aerospace, additive manufacturing, and more. An important area of research on new composites is their fracture toughness, which describes the condition for an initial crack to start propagating in the material. Effective fracture toughness, on the other hand, is a configurational property and depends on the geometric details of the part, such as the size and shape of the inclusions or fibers embedded in a matrix material to form composites. This work explores a special class of composites that are asymmetric toughness-wise, meaning that the effective toughness for the same composite is dependent on the direction of crack propagation. For example, when a matrix consists of a primary material with a secondary, stronger material as an asymmetric inclusion in the center of it, its toughness will change depending on where the crack is placed. This research seeks to examine several matrices of this type to determine the mechanistic basis for toughness asymmetry. Each matrix consists of a different inclusion geometry in the center. For some of the inclusions, the shape of the inclusion is varied based on a single variable to create a pattern that can be mathematically modeled to accurately predict the fracture toughness of that specific type of matrix. Once the models are created, cracks are added at various places on each matrix. Next, the models are simulated via the MEF90 software package. A nonuniform boundary displacement is applied to the matrix, and the propagation of the crack is examined using the J-integral and determining its maximum over the entire propagation time. Using the results of the simulations, a mathematical model is created to assist in predicting the fracture toughness of asymmetrical matrices and identify the maximum possible toughness asymmetry achievable from inclusion-matrix composites. This talk will highlight the results and discuss the importance of toughness-asymmetry in designing advanced composites. We expect that the outcomes of the research will have several ramifications towards improved understanding of crack propagation in complex composites. It will help us find new composites with unique properties for applications in defense, lightweight composites, aerospace, structural materials, and automobiles. Specifically, asymmetric composites could prove to be useful, as it could allow for the secondary material to be reduced, saving money. The secondary material, given that it is stronger, is likely to cost more than the primary material in the type of matrix discussed above. By creating models to predict the toughness of the material, our findings will help engineers and scientists save time, effort, and money by reducing the need for independent experiments and/or simulations in finding new composites with tailored toughness.

Presenting Author: John Papadopoulos NASA DE Space Grant

Presenting Author Biography: John is a senior studying Mechanical Engineering at the University of Delaware. He is primarily interested in composites and heat transfer/fluid mechanics, specifically within the aerospace field. He has research experience in additive manufacturing and composites, as well as industry experience as an intern at Siemens Healthineers. After finishing his undergraduate degree, he plans to get his Master's of Science in Mechanical Engineering at the University of Delaware and then begin working in industry as an engineer.

Authors:

John Papadopoulos NASA DE Space Grant
Zubaer Hossain University of Delaware