Resumen:

Lattice structures are architected cellular materials composed of periodic unit cells formed by rods, plates, or other structural elements. Advances in additive manufacturing have enabled precise control of lattice geometry, allowing these materials to achieve exceptional stiffness-to-weight ratios, strength, and energy-absorption capabilities. Architected lattice metamaterials with spatial property gradients offer new opportunities for tailoring stress-wave propagation, energy dissipation, and failure mechanisms under dynamic loading. This seminar examines the high-strain-rate behavior of polymeric lattice structures using split-Hopkinson pressure bar and direct impact experiments combined with high-speed imaging and digital image correlation. Quasi-static and dynamic tests on Kelvin lattices reveal the formation of localized deformation bands that initiate near the specimen center. The influence of lattice topology on transient dynamic response and the transition to shock compression is investigated through comparative studies of cubic, Kelvin, and octet-truss architectures. Full-field DIC measurements enable the definition of local shock parameters, while continuum shock analysis based on Rankine-Hugoniot jump conditions is used to quantify shock behavior. Results from density-graded lattices spanning bending-dominated, stretching-dominated, and auxetic topologies provide new insight into how topology, gradient design, and loading rate interact to govern stress-wave propagation, energy absorption, and failure evolution in architected materials. Explicit finite element simulations incorporating tensile failure are used to validate observed deformation modes and scaling trends.

Biografía: 

Guruswami (Ravi) Ravichandran es el profesor John E. Goode, Jr. de Ingeniería Aeroespacial y Mecánica en el California Institute of Technology. Obtuvo su doctorado en Ingeniería (Mecánica de Sólidos y Estructuras) por la Universidad de Brown. Es miembro de la Academia Nacional de Ingeniería de Estados Unidos y de la Academia Europaea, y miembro de ASME, SEM y AAM. Entre sus reconocimientos se encuentran la Medalla Timoshenko de ASME, la Medalla Eringen de SES y el Premio a la Conferencia Murray de SEM. Sus líneas de investigación se centran en la mecánica de materiales, incluyendo el comportamiento dinámico, la propagación de ondas, los materiales compuestos, los materiales multifuncionales, la micro/nanomecánica, la mecánica celular y los métodos experimentales.