Session: 01-07: Multifunctional Composites

Paper Number: 111103

111103 - Numerical Prediction of the Effective Mechanical Behavior of Interpenetrating Phase Composites Comprising Architected Nitinol Cores 

Interpenetrating phase composites (IPCs) are novel multifunctional co-continuous composite materials in which each constitutive phase forms a self-supporting cellular structure. This work focuses on the computational investigation of 3D IPCs comprising an architected shape memory alloy (SMA) microstructure embedded in an elastic-plastic second phase. The SMA reinforcement phase consists of Nitinol (NiTi) in a variety of architected topologies for which the constitutive material behavior is simulated by means of a user-defined material subroutine (UMAT) implemented in the finite element software Abaqus. Whereas the matrix phase consists of elastic-plastic AlSi10Mg for which the material data is sourced from in-house experiments. Various architectures considered for the NiTi reinforcement phase include several beam or strut-based architectures and mathematically-driven surfaces known as triply periodic minimal surfaces (TPMS). TPMS architectures promote several multifunctional attributes and reduce the effect of stress concentrations within the composite. Schoen I-WP (IWP), Schoen Gyroid (G), Schwarz Diamond (D), and Schwarz Primitive (P) are solid-network-based TPMS architectures that are considered, whereas strut-based reinforcement architectures include Diamond* (DS), Kelvin Cell (K), Octet (O) and Truncated Octahedron (TO). These co-continuous composites are modeled as representative volume elements (RVEs) and their functional properties are evaluated based on the volumetric homogenization technique with idealized periodic boundary conditions (PBCs). Elastic stiffness including uniaxial, bulk, and shear moduli, Poisson’s ratio, and NiTi phase transformation parameters (austenite-to-martensite phase transformation) along with effective strain recovery upon unloading are evaluated as effective mechanical properties of the considered IPCs. These functional properties are analyzed and compared based on the architecture of the NiTi reinforcement phase and its volumetric fraction (VF), considering different loading conditions. It is observed that both TPMS and strut architectures significantly affect the elastic uniaxial and shear moduli that increase with increased concentration of NiTi in the IPC. Furthermore, an exponentially increasing trend in overall strain recovery has been observed by increasing the VF of NiTi which results from the superelasticity of Nitinol. In terms of lattice architecture, IPCs comprising strut architectures showed the highest uniaxial moduli and lowest bulk moduli compared to solid-network TPMS-architected IPCs. Moreover, G-IPCs and P-IPCs showed the highest strain recovery. Experimental data sourced from two different studies in the literature are replicated to ensure the accuracy of finite element simulations.

Presenting Author: Shahzaib Ilyas Khalifa University of Science and Technology

Presenting Author Biography: I am a graduate student in the Mechanical Engineering department and a research assistant in Advanced Digital Additive Manufacturing Center at Khalifa University, Abu Dhabi, UAE. My research work focuses on the design and analysis of smart materials embedded as reinforcement phases in interpenetrating phase composites (IPCs). The motivation behind working on smart materials lies in their superelastic nature that makes them suitable to sustain large strains by remaining in the elastic region. Furthermore, my work also included the design of the IPCs that include architected reinforcements, especially triply periodic minimal surfaces (TPMS) and strut-based architectures.