Title:
Tough Cementitious Mortar-Silicone Multi-Material Composite Enabled by Automated Multi-Material Additive Manufacturing Process
Author(s):
Najmeddine
Publication:
Web Session
Volume:
ws_F24_Najmeddine1.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
11/3/2024
Abstract:
Cementitious materials remain susceptible to damage and cracking and suffer from low fracture toughness. This presentation provides a thorough experimental, analytical, and numerical examination of the mechanical properties of cementitious mortar-silicone multi-material composites, a development made possible by advancements in automated additive manufacturing processes. The research is enabled by the development of a new multi-material additive manufacturing (MMAM) platform that facilitates the sequential and/or simultaneous deposition of multi-material assemblies with diverse architectures. Inspired by the toughening mechanism found in natural systems such as Nacre, the enhancements in fracture toughness and strength of these composites were examined compared to traditional, monolithic cement structures. It is hypothesized that the presence of soft interlayers can promote the spread of damage. Notched and un-notched experiments (SENB and 3PB tests) were conducted on 3D-printed beams comprised of alternating layers of mortar and silicone to characterize the composite behavior under bending and Mode-I. Our recently developed phase-field cohesive zone crack propagation model for hard-soft architected materials was used to simulate the role of materials and geometric variables on mechanical response. LEFM was used to compare the simulation with theoretical benchmarks. The significantly enhanced fracture toughness is attributed to several new toughening mechanisms that were corroborated experimentally and numerically, owing to their hard-soft material interaction, and crack dissipation events such as crack deflection, crack propagation, and crack bridging. By numerically varying sample architecture (e.g., soft layer thickness) and material constitutive properties (e.g., different soft materials), a more thorough understanding of the various toughening mechanisms can be achieved for such multi-materials.