Mechanics of Topologically Interlocked Stereotomic Material Systems

Purdue University, West Lafayette IN

Investigators

Abstract

This research investigates the reconciliation of opposed properties in material systems through the use of stereotomic architectures. Engineers and scientists continuously search for high damage tolerant materials and structures. Stereotomy is the art of cutting materials into geometric shapes. The cut blocks are then assembled into complex structures. Scientists have recently discovered new principles for the assembly process. The result is Stereotomic Material Systems with new architectures realized as interlocking assemblies based on single and multiphase tessellations. This research then aims to reconcile opposed properties such as strength-toughness, brittleness-ductility, and hardness-wave speed. It also aims to find approaches to control such properties. The outcomes will have impact on several technologies, including flexible electronics, battery systems, armor, and high temperature structures. The PI will develop related educational modules in the context of engineering mechanics. These activities will introduce pre-college students to engineering principles. The awardee also will develop new graduate-level educational content on architectured material systems. He will engage undergraduate students in related research experiences. Advances in the scientific discourse on architectured material systems will be undertaken through an international symposium on the subject. A collaboration with a small business will enable the implementation of the stereotomic material systems. Stereotomic Material Systems (SMS) are assemblies of polyhedra on underlying tessellation patterns. The present work focuses on non-regular single-phase and multi-phase stereotomic material systems. For static loading, measurements of stiffness, strength and toughness under quasistatic loading are conducted. Under impact loading, experiments to determine wave front speed, unit element velocity and decay rates are planned. There are two main research questions: (1) given the large number of possibilities of tessellations providing potential architectural templates for SMS, and the option to consider multi-material systems, the question is how complexity in the SMS architecture would control SMS stiffness, strength and toughness. (2) since unit-to-unit element contact interactions in SMS are dependent on the degree of transverse deformation, the question is how such contact nonlinearity will manifest itself in the dynamics of the SMS response following impact loading, and how such dynamic response depends on SMS architecture complexity. Multi-material 3D printing is employed to manufacture specimens. Experiments under static and dynamic mechanical load are conducted. Theory and finite element simulation are used in the analysis.