CAREER: Linking Macroscopic Fracture to the Microscopic Behavior in Soft Composites

This Faculty Early Career Development Program (CAREER) award investigates the fracture behavior of soft composite materials by directly linking their macroscopic strength and toughness to their underlying microstructure and microscopic material properties. Soft composites consist of a compliant matrix, typically an elastomer, reinforced with particles or fibers, and they are widely used in applications ranging from automotive components such as tires to emerging technologies including soft robotic systems and flexible devices. In contrast to traditional hard composites, fracture in soft composites involves complex mechanisms such as large deformations, cavitation, and microstructural damage that interact across multiple length scales, making their failure behavior difficult to predict using existing theories. As a result, improved predictive mathematical models are needed to understand how microscopic failure processes collectively determine the macroscopic performance of these materials. This project addresses this need by developing a homogenization framework for fracture in soft composites, providing a systematic pathway to design stronger, safer, and more durable materials. The project also integrates a multi-tiered educational program spanning high school through graduate education, including the development of new computational educational tools, hands-on instructional modules, and design challenges centered on materials failure and engineering. Outreach activities will further provide research opportunities for high school students, professional development for teachers, and strengthened connections between academic research and industry. The CAREER project will support research aimed at establishing a numerical homogenization framework under large deformations that links microscopic fracture processes in soft composites to their macroscopic strength and toughness. The central objective is to develop a multiscale modeling approach that explicitly accounts for crack nucleation and propagation mechanisms within heterogeneous elastomeric microstructures. The research will build on a recently developed continuum fracture model that describes failure in elastic–brittle materials subjected to arbitrary multiaxial loading, enabling the framework to capture complex mechanisms such as cavitation, which is a key driver of crack nucleation in many soft composites. Using this model, the project will investigate the limit of separation of length scales in soft heterogeneous materials and derive macroscopic governing equations and effective fracture properties based on solutions to two experimentally realizable boundary-value problems. The resulting framework will be validated using representative composites based on natural rubber and styrene–butadiene rubber, two of the most widely used elastomers in engineering applications. In addition, the theoretical framework will extend to hard composites, including ceramic- and epoxy-matrix systems, as a limiting case. The resulting methodology will advance the theoretical foundations of fracture mechanics and homogenization while enabling predictive design of heterogeneous materials with improved resistance to fracture and failure. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2541441 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Aditya Kumar | Institution: Georgia Tech Research Corporation, ATLANTA, GA | Award Amount: $638,740 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2541441 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2541441.html