Mechanical Response of Materials Investigated through Novel In-situ Experiments and Modeling: Session VI
Sponsored by: TMS Structural Materials Division, TMS: Thin Films and Interfaces Committee, TMS: Advanced Characterization, Testing, and Simulation Committee
Program Organizers: Saurabh Puri, VulcanForms Inc; Amit Pandey, Lockheed Martin Space; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization; Dongchan Jang, Korea Advanced Institute of Science and Technology; Jagannathan Rajagopalan, Arizona State University; Josh Kacher, Georgia Institute of Technology; Minh-Son Pham, Imperial College London; Robert Wheeler, Microtesting Solutions LLC; Shailendra Joshi, University of Houston
Wednesday 2:00 PM
March 17, 2021
Room: RM 17
Location: TMS2021 Virtual
Session Chair: Jagannathan Rajagopalan, Arizona State University; Josh Kacher, Georgia Institute of Technology
2:00 PM
Synchrotron X-ray Studies of Deformation and Failure in Cold Spray Composites: Lewei He1; Darren Pagan1; Qi An1; Aaron Nardi2; Mostafa Hassani1; 1Cornell University; 2U.S. Army Research Laboratory
Cold spray is an effective solid-state process for the fabrication of composite materials. Different material classes including metals, ceramics, and intermetallics can be co-deposited in supersonic nozzles to make composite materials, enabling a favorable combination of the properties of the constituent phases. While improved mechanical properties of cold spray composites have been reported in a variety of material systems, it is often challenging to deconvolute the collective mechanical behavior to understand the mechanistic contributions of the constituent phases. Here, we use high energy synchrotron X-rays to study deformation and failure of Ni-CrC cold spray composites. We conduct in-situ loading experiments where synchrotron X-ray diffraction and computed tomography are utilized at multiple load steps to measure the evolution of phase-specific lattice strains and characterize failure modes. Our work provides understanding of the load partitioning between the soft and hard phases and unravels the key failure mechanisms of cold spray composites.
2:20 PM
Metal Foams: Linking Dynamic CT Results to Simulation and Modeling: Luke Hunter1; Wesley De Boever2; Martina Humbert3; Andreas Griesser3; 1Tescan USA, Inc; 2TESCAN XRE; 3Math2Market
Metal foams play an important role in our lives and are used in a wide range of applications, from energy dissipation (safety) to energy saving (lightweighting). When metal foams are an integral part of a structure the mechanical characteristics and their response to external load need to be well understood. To facilitate a greater understanding, we have utilized lab-based dynamic computed tomography (CT) to visualize uninterrupted compression of aluminum metal foams and coupled these results to software simulations of the same samples. Two samples with different levels of cell density are tested, analyzed, and simulated. Data collected from the first sample is used to first analyze and determine material characteristics of the material, which are, in turn, applied as inputs in a compression simulation of a second sample. The second sample is also physically tested with dynamic CT to provide further verification and improvement of the simulation and modeling results.
2:40 PM
Non-destructive Inspection of Contaminated Epoxy Plates Using Propagating Acoustic Waves: Isabel Mcbrayer1; Fady Barsoum2; 1Embry-Riddle Aeronautical University; 2Embry-Riddle Aeronautical University
The increased use of composites demands the development of repair processes that can guarantee lasting strength restoration so as to minimize the frequency of expensive downtime. Weak bonds are a concern for ensuring the structural integrity of a repair and although epoxy resins are continuously being developed to have higher strengths than their predecessors, factors such as contamination levels in the repair bond may result in poor adherence and inhibit overall bond strength. This research compares the response of virgin epoxy plates to short duration acoustic excitation with that of epoxy with varied levels of contamination (0.5%, 1% and 10%). Acoustic events were simulated at multiple distances from a high-fidelity displacement sensor, using the Hsu-Nielsen technique, and the experimental signals were then assessed in the time-frequency domain, using the wavelet transform. Results were then compared with previous research on unidirectional carbon fiber laminates with a single contaminant in between plies.
3:00 PM
Rhodium and Cobalt Oxidation: A Nanoscale Study by In-situ and in Operando Atom Probe Tomography: Sten Lambeets1; Norbert Kruse2; Daniel Perea1; 1Pacific Northwest National Laboratory; 2Washington State University
An in situ instrument development effort is reported dedicated to studying gas/metal interactions relevant to heterogeneous catalysis and early stages of oxidation via Atom Probe Tomography and Microscopy (APT/M). An in-situ reactor cell connected to an atom probe instrument is used to expose specimens to reactive gas environments, where temperature, pressure are well controlled. We demonstrate that the reactor cell and APT/M combination provides insight for a better mechanistic understanding surface and subsurface structural changes in the O2/Rh and O2/Co systems. Tracking oxygen atoms from surface activation to bulk penetration into Rh along specific surface facet structures, we found a local heterogeneity of Co2O and CoO, where Co2O was found progressively deeper as oxidation progressed. Additionally, we will also describe the unique in operando oxidation of Co within the analysis chamber of an atom probe instrument allowing us to map, in space and time, the formation of various oxide species.
3:40 PM
Experimental Measurements of Anisotropic Mechanical Behavior of 𝛽-HMX Crystals: Ayotomi Olokun1; Abhijeet Dhiman1; Vikas Tomar1; 1Purdue University
Due to their complex microstructure, energetic materials (EMs) are known to be sensitive to mechanical and thermal stimuli, which may lead to sudden localized temperature rise resulting in unintentional detonation. With few exceptions, simulation of the mechanical behavior of HMX-based EMs in the mesoscale generally overlooks the anisotropic thermomechanical properties of HMX crystals which can be vital in determining the performance of HMX-based EMs. In this work, we obtained elastic and viscoplastic constitutive parameters for modelling the mechanical behavior of the (010), {110}, and {011} oriented faces of 𝛽-HMX. Elastic constitutive parameters are obtained via nanoindentation experiments on HMX crystals and HMX-based Polymer Bonded Explosives (PBX). Similarly, dynamic impact is performed to characterize the anisotropic viscoplastic model parameters to fit a viscoplastic power law. Using these parameters, we capture defining anisotropic constitutive properties of HMX for high accuracy in prediction of thermomechanical behavior and sensitivity of HMX-based EMs.