Mechanical Response of Materials Investigated Through Novel In-Situ Experiments and Modeling: Session V
Sponsored by: TMS Structural Materials Division, TMS Functional Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Thin Films and Interfaces Committee
Program Organizers: Saurabh Puri, Microstructure Engineering; Amit Pandey, Lockheed Martin Space; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization; Dongchan Jang, Korea Advanced Institute of Science and Technology; Shailendra Joshi, University of Houston; Josh Kacher, Georgia Institute of Technology; Minh-Son Pham, Imperial College London; Jagannathan Rajagopalan, Arizona State University; Robert Wheeler, Microtesting Solutions LLC

Wednesday 2:00 PM
March 2, 2022
Room: 206B
Location: Anaheim Convention Center

Session Chair: Nathan Johnson, Stanford Univ; Eric Payton, University of Cincinnati

2:00 PM  Invited
A Predictive Capability for Mechanical Behavior of Additively Manufactured Lattice Structures: John Carpenter1; Donald Brown1; Vimal Chaitanya2; Borys Drach2; Zachary Paesani2; Nathan Johnson3; Jenny Wang4; Maria Strantza4; 1Los Alamos National Laboratory; 2New Mexico State University; 3SLAC National Accelerator Laboratory; 4Lawrence Livermore National Laboratory
    Additive manufacturing (AM) has allowed for the fabrication of complex lattice structures that are viewed favorably for their mass/stiffness ratio. Their complex nature also makes them challenging to fabricate, inspect, and model with many lattices failing to meet mechanistic expectations. In this talk, 1-ID at the Advanced Photon Source was used to measure local strain in struts within an AM Ti-5Al-5V-5Mo-3Cr lattice under compressive loading to strut failure. It was found that, despite the use of post-process heat treatments, some amount of retained residual stress was present and was associated with the fabrication sequence. Simulated residual strains, validated through experiments, were then coupled with computed tomography to provide inputs to an FEA – based model architecture. It was observed that incorporating residual strain with model geometry allowed for an accurate prediction of local elastic strain distribution and location of failure during compressive loading.

2:30 PM  Invited
Toward Improved Constitutive Behavior Models Sensitive to High Strength Steel Microstructures through Advancements in Data Analysis Tools: Eric Payton1; 1Air Force Research Laboratory
    Improved microstructure-sensitive models are desired for predicting constitutive behavior of high strength steels. Fitting models of viscoplastic response of these alloys under dynamic loading conditions remains challenging due to testing costs, microstructural effects, and experimental variability, which propagates into model parameters during fitting. The complex, hierarchical microstructure of quench-and-temper and maraging steels presents a challenge for quantitative characterization, especially for fine austenite grain sizes where fewer variants may be observed. In the present work, several high strength steels are subjected to rapid thermal cycling to refine the microstructures and mechanically tested using split Hopkinson apparatus. The microstructures are characterized using an algorithm probabilistic reconstruction of the prior austenite microstructure from room temperature electron backscatter diffraction observations. This talk presents an overview of our efforts to develop novel model fusion, uncertainty quantification, synthetic microstructures, and data clustering algorithms to link microstructures to dynamic behavior of high strength steels.

3:00 PM  
A Numerical Study on Surface Effect in Hexagonal Slip Activity: Cathy Bing1; Thomas Bieler1; Philip Eisenlohr1; 1Michigan State University
    Slip in hexagonal metals depends on the activity of multiple slip families, such as basal <a>, prismatic <a>, or pyramidal <c+a>, that typically require different magnitudes of resolved shear stress to trigger their activation. Frequently, surface observations of slip, i.e. linear traces corresponding to surface steps, are utilized to investigate and quantify these differences in critical resolved shear stress (CRSS). Since the resulting values are not necessarily in agreement with measurements based on bulk techniques, the question arises whether the surface systematically biases the slip activity. We compare simulations of plastically strained polycrystalline structures with and without introducing a surface under a variety of CRSS ratios. A significant difference in relative slip family activity between surface and interior grains is observed. Slip families with the lowest CRSS tend to get amplified near the surface while families with higher CRSS are suppressed. Possible mechanisms and reasons of the results are discussed.

3:20 PM Break

3:40 PM  
Inferring Dynamic Mechanical Properties of Materials Using a Combination of High-rate Machining Experiments and Simulations: Umair Bin Asim1; Michael Demkowicz1; Ankit Srivastava1; 1Texas A&M University
    We demonstrate a method for inferring high strain rate deformation response of materials from high-speed cutting. The approach compares experiments and finite element simulations for a specified set of input cutting parameters, including cutting velocity, depth of cut, rake angle, and tool-tip radius. It then optimizes material constitutive parameters to minimize the discrepancy in measured response variables, such as cutting and thrust forces at the tool and the chip morphology. The mechanical behavior of material is represented using isotropic elasticity as well as Johnson-Cook plasticity and damage models, which take into the account the effect of strain rate and thermal softening encountered during high-speed cutting. The proposed approach enables rapid assessment of material deformation at strain rates of 10 s-1 to 105 s-1 without recourse to resource intensive procedures, such as split Hopkinson pressure bar testing.

4:00 PM  
Strain Localization in Metastable Beta Ti Alloys in Relation to the Beta Structure: Azdine Nait-Ali1; Ana´s Huet1; Samuel Hemery1; 1Isae-Ensma
    Metastable β titanium alloys are widely used for room temperature applications in the aerospace industry. They derive their attractiveness from a very high specific resistance. Prior studies have highlighted strain localization in relation to the β structure. However, this feature has attracted little attention. In the present study, a mechanistic understanding of the role of the β phase in the onset of plasticity was investigated. Full field simulations were performed using a spectral solver implemented in the FoXTRoT in-house code. This method is essential to consider large enough polycrystalline aggregates to explicitly simulate the anisotropic behavior of the two phases at the β grain scale. Simulation data were finally compared to experimental deformation behaviors characterized using a combination of in-situ testing and digital image correlation on various Ti alloys.