RUI: revealing the impact of stimulus variability on the stability of structures made from environmentally responsive materials

Hope College received a $278,677 Project Grant from the National Science Foundation (NSF) Engineering program (CFDA 47.041), Division of Civil, Mechanical, and Manufacturing Innovation, effective August 1, 2025, through July 31, 2028. This Research at Undergraduate Institutions (RUI) award funds fundamental research investigating bistable structures constructed from environmentally responsive materials, with a focus on understanding how non-uniform thermal stimuli influence switching behavior in bistable arches. The research applies nonlinear Euler-Bernoulli beam theory to develop analytical and semi-analytical models that elucidate the impacts of thermal non-uniformity and structural imperfections on system stability, with experimental validation using photothermal techniques.

The award supports research intended to establish general principles applicable to active multi-stable structures and devices with applications in advanced robotics, micro-electromechanical systems, and next-generation materials. A critical component of this award is its emphasis on workforce development, providing undergraduate and high school students with early research experience and mentoring in STEM disciplines. By addressing a gap in the study of morphing materials and structures and moving beyond uniform stimulus assumptions, this research aims to enable rational design breakthroughs while building a competitive STEM workforce pipeline.

Abstract

This facilitating research at primarily undergraduate institutions (RUI) project will fund research that investigates the fundamental mechanics of bistable structures, which can rapidly switch between stable configurations, and are essential components in both natural and technological systems, such as hummingbird beaks and robotic mechanisms. In recent years, a promising design approach has emerged, utilizing materials that respond to environmental stimuli like light or heat, enabling structures to autonomously adapt to operational conditions. This award will support research into how non-uniform environmental stimuli interact with system design parameters to influence the switching behavior of bistable arch building blocks. Understanding these interactions intend to enable the rational use of non-uniformity to drive design breakthroughs in areas of national technological interest, such as advanced robotics, micro-electromechanical systems, and next-generation materials. Additionally, the project seeks to contribute to the development of a competitive stem workforce by providing early research experience and mentoring for undergraduate and high school students. The objective of this project is to fill a critical GAP in the study of morphing materials and structures by analyzing the effects of non-uniform thermal stimuli on bistable arches. While most studies assume a uniform stimulus or rely solely on numerical methods, this project aims to develop general, fundamental principles that can be applied broadly to active multi-stable structures and devices. The research will utilize nonlinear euler-bernoulli beam theory to create analytical and semi-analytical models, providing insight into the impact of thermal non-uniformity and identifying how imperfections influence stability. Experimental validation will be performed using photothermally excited bimetal arches, helping to refine the models and improve understanding of system behavior. The knowledge gained looks to pave the way for new design strategies in modular morphing structures and metamaterials, advancing responsive materials systems and driving innovation in cutting-edge applications. 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.- subawards are not planned for this award.