Agile In-operando Nondestructive Evaluation during Additive Manufacturing of Naval Composite Materials
Abstract
The scientific community is fascinated with the light-matter interactions, spanning the entire range of the electromagnetic spectrum, to gain deeper insights into the fundamental mechanisms responsible for the intrinsic response of natural and synthetic materials. The latter is imperative for developing advanced defense systems expected to operate in extreme environments. The proposed research aims to fully develop a novel terahertz strainmetry system, i.e., a transformative experimental solid mechanics technique to probe and quantify internal strains, capturing the microstructural evolutions of cellular and bulk polymers during deformation and uncovering the fundamental mechanisms responsible for the overall mechanical behavior. The scientific outcome of the proposed research is the development of the first-of-its-kind deep-learning-based terahertz image correlation analyses for probing the internal strains before, during, or after loading in ungraded and density-graded polymeric foam structures. Polyurea foam with energy-tunable Poisson s ratio will be used as a model material system to evaluate the capabilities of the proposed terahertz strainmetry in assessing the internal strains within loaded foam samples (ungraded and density-graded) as a function of the strain rate. This novel experimental mechanics approach departs from the surface-limited conventional digital image correlation techniques with higher accuracy and robustness, leveraging the capabilities of deep machine learning algorithms. We recently demonstrated that Poisson s ratio of our hierarchical, self-reinforced polyurea foams is self-tuned based on the energy of the incoming impact, where the foam approaches the auxetic response (i.e., negative Poisson s ratio) as the impact energy increases. Our polyurea foam is an exciting scientific and technological testbed based on its tunable microstructure and properties with many potential naval applications, including protective padding in soldier helmets and bulletproof vests and cores in blast-tolerant sandwich structures in naval applications, to name a few prominent defense applications. However, knowledge about the underlying deformation within the cell structure remains ambiguous, which will be remedied by the proposed research. The knowledge from the proposed investigations using polyurea foams applies to the broad class of polymers, polymeric foams, and ceramics (i.e., non-polar materials). Therefore, the overall outcomes of the proposed work are(1) versatile terahertz strainmetry for in-situ and ex-situ microstructural imaging and solid mechanics characterization of non-polar materials; (2) revealing the elastic, viscoelastic, and plastic deformation mechanisms of bulk and cellular polymers and at the interface of skins/cores in sandwich structures; and (3) providing experiential training on state-of-the-art experimental and computational tools to students from underserved and underrepresented minority groups. The proposed research is potentially transforming the state-of-the-art in experimental solid mechanics by developing a novel approach to continually monitor the internal microstructural evolution as a function of mechanical loading, nondestructively and noninvasively, revealing the intrinsic process-structure-property-performance interrelations. Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 15, 2024
- Source ID
- N000142412346
Entities
People
- George Youssef
Organizations
- Office of Naval Research
- Salk Institute for Biological Studies
- United States Navy