Mechanical Response of Materials Investigated through Novel In-situ Experiments and Modeling: Session IV
Sponsored by: TMS Structural Materials Division, TMS: Thin Films and Interfaces Committee
Program Organizers: Saurabh Puri, VulcanForms Inc; Amit Pandey, Lockheed Martin Space; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization; Dongchan Jang, KAIST; 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
February 26, 2020
Room: 32B
Location: San Diego Convention Ctr
Session Chair: Shailendra Joshi, University of Houston; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization
2:00 PM Introductory Comments
2:10 PM Keynote
On Crystallographic and Material Hardening Aspects in Ductile Damage of Hexagonal Close Packed Metals: Shailendra Joshi1; 1University of Houston
The remarkable crystallographic plastic anisotropy, tension-compression asymmetry and strong texture effects in low symmetry hexagonal close packed (HCP) materials are often referred to as origins of damage intolerance. While post-mortem experimental evidences indicate ductile processes at play, the role of anisotropic slip and twinning on the rates and states of damage accumulation remains elusive. In this talk, we present the micromechanics of void evolution in HCP materials using three-dimensional, finite element crystal plasticity unit cell calculations. Emergent interactions between void growth with deformation mechanisms leading to void coalescence are discussed with implications on the damage tolerance of technologically important HCP alloys. The investigation provides insight for improved descriptions of continuum damage models.
2:50 PM
Microstructure and Micromechanical Field Evolution During Dynamic Recrystallization: A Crystal Plasticity-phase Field Simulation Study: Supriyo Chakraborty1; Chaitali Patil1; Yunzhi Wang1; Stephen Niezgoda1; 1Ohio State University
To study the evolution of microstructure and micromechanical fields during hot deformation of metals a 3D full field model for dynamic recrystallization has been proposed. For this purpose, a fast Fourier transform based elasto-viscoplastic (EVP-FFT) crystal plasticity model has been coupled with a phase field model. To capture the underlying physical mechanisms of high temperature deformation a dislocation density based constitutive model has been used. Simulation results successfully captures the effect of temperature, strain rate and initial grain size on stress-strain behavior and grain size evolution during dynamic recrystallization. Decrease in Local stress and elastic strain have been observed inside the recrystallized grains. A jump in local strain rate has been observed inside the recrystallized grains which decreases rapidly on further deformation. Additionally, our simulation results reveal that the rate of dislocation accumulation is much faster inside the recrystallized grains in comparison to the deformed matrix.
3:10 PM
Shape Fidelity and Mechanical Response in Micro Pattern Replication by Molding: Bin Zhang1; Mohammad Dodaran1; Shuai Shao1; Junseo Choi1; Sunggook Park1; Wenjin Meng1; 1Louisiana State University
Forming nano-/micro- patterns on metal surfaces by compression molding with patterned punches has potential applications to microsystem technologies. Geometric fidelity and mechanical response of molding are of critical importance. We highlight these issues through a series of instrumented double-punch molding experiments, which show that the plastic flow to fill the gap between two identically dimensioned rectangular strip punches and the characteristic molding pressure exhibit various mechanical size effects as the characteristic dimension decreases from ~100µm to ~1 µm. Accompanying 3D and 2D plane-strain elasto-plastic finite element analyses, based on conventional and strain gradient plasticity, have been performed to provide insights on the effects of punch aspect ratio, spacing, friction, and material length scale on this particular metal forming process. Our results shed light on design considerations for molding replication at the microscale, and illustrate the peculiarities of materials’ response when molding replication is pushed to micron dimensions
3:30 PM Break
3:50 PM Keynote
Numerical Study of Plastic Deformation Mechanisms in a New Generation Fe-TiB2 Steel Composite Using a FFT-based Model: Julien Genée1; Stephane Berbenni1; Nathalie Gey1; Julien Guyon1; Frederic Bonnet2; 1Laboratoire d’Étude des Microstructures et de Mécanique des Matériaux (LEM3), UMR 7239, CNRS / Université de Lorraine; Laboratory of Excellency DAMAS, Design of Alloy Metals for low-mAss Structures; 2Research & Development Automotive Products, AcelorMittal Maizières
This study aims at getting a better understanding of plastic mechanisms in a new generation steel composite composed of a ferritic matrix and TiB2 ceramic reinforcements. Especially, the objective is to evaluate the very heterogeneous distribution of mechanical fields between the ductile matrix and the hard particles. Indeed, localization of deformation in the Fe-TiB2 composite could lead to premature damage initiation (debonding at matrix/particle interface or particle fracture).To this end, a full-field crystal plasticity simulation approach, based on the Fast Fourier Transform method (FFT) and taking into account the evolution of Geometrically Necessary Dislocations (GND) densities distribution, has been developed. Synthetic as well as realistic microstructures – based on 2D and 3D advanced characterizations in a FEG-FIB SEM system equipped with an EBSD sytem – serve as input for simulations in order to assess the relation between internal length scales and local GND distribution, stress and plastic strain fields.
4:30 PM
Multiscale Modeling to Determine Bulk Material Property from Miniature Specimen Testing: Farhan Rahman1; Tasnim Hassan1; 1North Carolina State University
A novel multiaxial miniature testing system (MMTS) with high temperature and in-situ SEM testing capabilities has been developed. Tubular specimen of 1-2 mm diameter with different wall thicknesses can be tested with the MMTS. To obtain bulk material properties from such miniature specimens, it is important to investigate miniature specimen size effect. We report crystal plasticity based multiscale modeling to predict representative volume element and miniature specimen size to obtain bulk material properties from testing with the MMTS. Metallographic analysis was performed on SS304 tubular specimen to obtain grain size and orientation information to develop synthetic microstructure for performing multiscale analyses. Crystal plasticity finite element analysis (CPFEA) was performed to investigate dependence of stress-strain responses on tube wall thickness. This coupling of multiscale modeling and MMTS testing will contribute in rapid development of new material.
4:50 PM
Experimental and Numerical Investigation into Mechanical Degradation of Polymers and Polymer Composites: Vinamra Agrawal1; Asha-Dee Celestine1; Brandon Runnels2; 1Auburn University; 2University of Colorado Colorado Springs
The process of mechanical degradation of polymers subject to water and heat diffusion is studied using experimental methods and continuum damage modeling. As the water and heat diffuses within the composite, strength and moduli of the composite degrade due to breaking down of polymer chains brought upon by underlying chemical reactions. Samples were created using injection molding and 3D printing, soaked in water at different temperatures and subject to tension and flexure tests.Model parameters, such as glass transition temperature, strength and modulus, were calibrated from experimental studies. The damage model depends on the water concentration, temperature, time history and the stress states at every point. The damage model was implemented using a computational scheme that solves conservation and evolution laws using a multilevel, multi-grid adaptive mesh refinement scheme. The model is tested by calculating effective moduli by recreating ASTM test conditions numerically and validating against experimental observations.