Additive Manufacturing Modeling, Simulation, and Machine Learning: Microstructure, Mechanics, and Process: Mechanical Properties
Program Organizers: Jing Zhang, Purdue University in Indianapolis; Brandon McWilliams, US Army Research Laboratory; Li Ma, Johns Hopkins University Applied Physics Laboratory; Yeon-Gil Jung, Korea Institute of Ceramic Engineering & Technology
Monday 8:00 AM
October 10, 2022
Room: 303
Location: David L. Lawrence Convention Center
Session Chair: Jing Zhang, Indiana University - Purdue University Indianapolis; Li Ma, Johns Hopkins University Applied Physics Laboratory; Brandon McWilliams, CCDC Army Research Laboratory; Yeon-Gil Jung, Changwon National University
8:00 AM
Effects of a Novel Post Processing Technique on Mechanical Performance of AlSi10Mg Produced via LPBF: John Lewandowski1; Austin Ngo1; Jag Sankar2; Tony Schmitz3; Jian Cao4; Glenn Daehn5; 1Case Western Reserve University; 2North Carolina A & T State University; 3University of Tennessee-Knoxville; 4Northwestern University; 5The Ohio State University
Additive Manufacturing (AM) processes have versatile capabilities but are susceptible to the formation of non-equilibrium microstructures, process-induced defects and porosity, which have deleterious effects on the mechanical performance of AM-processed structural materials. A novel post processing technique was investigated as a method of microstructure manipulation while reducing process defect severity to improve mechanical properties. AlSi10Mg processed via LPBF over a range of process parameters were characterized, followed by a novel post processing technique to impart beneficial changes in mechanical performance. Both initial and post processed material were analyzed with EBSD and tomography, while fracture surfaces were analyzed using OM, SEM, and metrology methods. Initial modeling of the novel post processing technique has also been conducted. The effects of this novel post processing technique on the mechanical behavior of LPBF AlSi10Mg will be presented along with possible extension to other AM-processed materials.
8:20 AM
A Modeling Tool for Mechanical Performance Prediction and Qualification of Additive Manufacturing Parts: Behrooz Jalalahmadi1; Jingfu Liu1; Ziye Liu1; 1Sentient Science
Sentient has developed a predictive modeling tool for components built using AM to assess their performance, with consideration of microstructural properties. Multiple microstructural features and behaviors specific to AM materials are considered in the tool: effect of AM build process on residual stress and porosity left in the part after build process, and microstructure resulted due to build process parameters. We simulate AM build process considering parameters involved during build process. Our predictive model has three main modules: process modeling, microstructure modeling, and fatigue modeling. The validation of our modeling tool is verified using experimental testing. The tool provides different types of output for user, including microstructure map, grain distribution data, porosity map, residual stress contours, thermal contours, S-N data, fatigue crack animation, and Weibull distribution. This tool significantly reduces required expensive and time-consuming experimental testing, thereby improving design process, increasing reliability and durability, and reducing cost of operation.
8:40 AM
Computational Fluid Dynamics Data-driven Heat Source Model for Finite Element Process Simulation in Laser Powder Bed Fusion Additive Manufacturing: Seth Strayer1; Florian Dugast1; Albert To1; 1University of Pittsburgh
Thermal field prediction of the laser powder bed fusion (L-PBF) process via the finite element (FE) method can help optimize the process while avoiding the cost of experimental techniques. However, FE models require the abstraction of critical physics into an analytical heat source model, which is not accurate for simulating moderate to high energy melting regimes. This work attempts to mitigate these issues via a data-driven heat source model. In this approach, the thermal fields from a higher-fidelity computational fluid dynamics (CFD) simulation obtained via deep learning are imposed onto the FE solution and entirely replace any analytical heat source model. The resulting thermal fields and melt pool sizes are within 10% error regarding the CFD simulation and experiment, respectively, while the computational expense is significantly reduced compared to the CFD simulations. Hence, this model provides a path for improving the accuracy and potential of thermal FE modeling for L-PBF.
9:00 AM
Residual Stress Modeling during Wire Arc Additive Manufacturing of Low Temperature Transformation Alloy: Guru Charan Reddy Madireddy1; Yousub Lee1; Kyle Saleeby1; Wei Tang1; Thomas Feldhausen1; Alex Plotkowski1; 1Oak Ridge National Laboratory
Under dynamic printing conditions and complex geometries in wire-arc additive manufacturing, varying thermal cycles and internal stress buildup causes unfavorable part deformation. Residual stress mitigation strategies have been mainly developed to reduce inhomogeneity in heat distribution and cooling rate. In this work, a part was printed on a wire-arc based additive system (Tormach) using low temperature transformation (LTT) alloy, which induces compressive stress through martensite phase transformation. The phase transformation induced stress is predicted using finite element method (FEM) integrated with phase transformation models, Weibull cumulative distribution function and Koistien-Marbuger. The temperature profile was validated against in-situ infrared camera and thermocouple data. Significant stress reduction was observed in the model due to the martensite transformation. The phase transformation and residual stresses from FE model will be validated.
9:20 AM
Modified Inherent Strain Modeling of Residual Stress and Distortion in WAAM and LPBF Processes: Wen Dong1; Albert To1; 1University of Pittsburgh
The laser powder bed fusion (L-PBF) and wire-arc additive manufacturing (WAAM) processes have been widely used to manufacture metal parts layer-by-layer in various sizes, geometries, and materials. However, due to the high-energy heat source, complex scanning path, and limited heat dissipation, the residual stress and distortion in the as-built part are inevitable and limit the application of these processes. The modified inherent strain (MIS) method has been developed for fast prediction of residual stress and distortion of metal AM parts. It includes three types of numerical simulations: (1) detailed process simulation to extract inherent strains at different pre-heat temperatures through thermomechanical analysis; (2) flash heating simulation to acquire the pre-heat temperature for each layer for a given part design; (3) MIS-based part-scale simulation to apply inherent strains accordingly to each layer of the part. The proposed method is experimentally validated and shows good accuracy for a few printed parts.
9:40 AM
Anisotropic Distortion Modeling during Sintering of Binder Jet Printed Parts: Basil Paudel1; Albert To1; 1University of Pittsburgh
During sintering of binder jet printed (BJP) parts, non-linear and often anisotropic distortion is seen with shrinkage values in the range of ~5-25%. The design complexity of the part combined with high temperature creep makes prediction of the final sintered geometry more challenging. In the present study, an anisotropic viscoplastic constitutive model comprising of minimum number of material parameters is developed to predict the distortion during sintering of the stainless steel 316L BJP parts. The effects of friction and gravity are considered. The model is implemented using custom subroutine within Ansys and is used to simulate the distortion. The results from the numerical analysis using the identified parameters are validated against experimental measurements. It is shown that the calibrated model predicts the anisotropic shrinkage and shape distortion reasonably well during the sintering process.
10:00 AM Break
10:20 AM Cancelled
Accuracy of Different Thermomechanical Simulation Approaches for Predicting Residual Stress and Distortion in Laser Powder Bed Fusion: Chien Vo1; Albert To1; Alaaeldin Olleak1; Wen Dong1; Florian Dugast1; 1University of Pittsburgh
The inherent strain method and layerwise thermomechanical method have been widely used to simulate the residual stress and distortion in laser powder bed fusion (L-PBF) parts; however, their accuracy has not been rigorously tested. In this work, these methods will be compared with the part-scale scanwise thermomechanical simulation model which serves as the ground truth. To achieve this, these process simulation methods will be implemented under the finite element method framework with matrix-free algorithm with voxel mesh and adaptive meshing to facilitate their simulation on graphical processing unit (GPU) cores. These schemes together aim to reduce the total computational time it takes to predict residual stress and distortion in L-PBF parts. The various methods implemented on the same GPU-based solver will be compared for their accuracy and efficiency on several parts.
10:40 AM
Mesoscale Modeling of the Additively Manufactured 316L: Effects of Microstructure and Microscale Residual Stresses: Mohammadreza Yaghoobi1; Yin Zhang2; Krzysztof S. Stopka3; David J Rowenhorst4; Ting Zhu2; John E. Allison1; David L. McDowell2; 1University of Michigan; 2Georgia Institute of Technology; 3Purdue University; 4US Naval Research Laboratory
Microstructure and residual stresses play a key role in the response of components produced by Additive Manufacturing (AM). While macroscopic residual stresses are commonly considered in computational models, the effect of micro-residual stress is less well established. The current work investigates the effects of microstructure and micro-residual stresses on the response of AM stainless steel. A crystal plasticity model is developed as an extension of the Armstrong–Frederick cyclic hardening plasticity model which captures the tensorial evolution of backstress induced due to micro-residual stresses. Open source PRISMS-Plasticity and PRISMS-Fatigue software are used to conduct large scale CPFE simulations and fatigue analysis. Reconstructed AM stainless steel microstructures are used to investigate the interaction of micro-residual stresses with the microstructural features on cyclic responses including stress-strain and elastic lattice strain. The effect of micro-residual stresses and microstructure on the microscopic response including the local plastic slip and fatigue driving forces is addressed.
11:00 AM
Crystal Plasticity Modeling Effort to Capture Microstructural Variations in Cold Sprayed Materials: Aulora Rusk1; Yubraj Paudel1; Ryan Cochran1; Shiraz Mujahid1; Marc Pepi2; Hongjoo Rhee1; Peter Czech3; 1Center for Advanced Vehicular Systems; 2Army Research Laboratory; 3American Lightweight Materials Manufacturing Innovation Institute
Microstructures and mechanical properties of cold spray additively manufactured Aluminum 6061 showed non-uniformity with spatial variation in microstructure and mechanical properties affecting the overall response of the additively manufactured parts. The high-velocity impact of powder particles created intersplat boundaries with regions of high dislocation densities and sub-grain structures. Full-field crystal plasticity simulations showed that the distribution of smaller grains along the intersplat regions is responsible for localized stress spots and larger grains away from intersplat boundaries accommodate initial plasticity. In this work, we attempt to implement the effects of grain size and distribution of smaller grains along intersplat boundaries using the grain size and powder size distribution function to accurately predict the deformation response of cold sprayed material using a mean-field viscoplastic self-consistent model. Then, the model was calibrated, validated, and verified using uniaxial tension and compression data at various strain rates.
11:20 AM
Phase Stability and Mechanical Properties of Ni-Al and Ni-Cr Binary Solid Solutions Using CASTEP Supercell Approach: Vielet Hilane1; Maje Phasha1; Marandela Mulaudzi1; Josias Van der Merwe2; 1Mintek; 2University of the Witwatersrand
The structural properties, phase stability and elastic properties of Ni-Al and Ni-Cr compounds were systemically investigated using first principle calculations based on density functional theory. The calculations were calculated using CASTEP supercell approach with ultrasoft pseudopotential. The structures comprised of 16 and 32 atoms built using 2x2x2 BCC and FCC unit cells, respectively, were geometry optimized using cut-off energy of 500 eV with k-points of 8 x 8 x 8. The resulting predicted lattice constants were found to be in agreement with experimental trends and in accordance with the Vegard’s law for binary solid solutions in both Ni-Al and Ni-Cr systems. The calculated heat of formation for binary FCC Ni-Al solid solutions revealed higher thermodynamic stability as Al concentration increased whereas the solubility of Cr in Ni was less favourable and limited to less than 25 at.% at 0K. The elastic constants of these binary solid solutions were also calculated.
11:40 AM
Additively Manufactured Multi-metallic Design for Ti-6Al-4V and Inconel 718 Joining by Scheil-Gulliver Ternary Projection Diagrams: Saeid Alipour Masoumabad1; Arezoo Emdadi2; 1Missouri University of Science & Technology; 2Missouri University of Science and Technology
One of the existing challenges in joining of Ti-6Al-4V and Inconel 718 is the formation of Ti-Ni intermetallic compounds that fail to achieve acceptable mechanical properties for using in hybrid structures. This paper aims to introduce a new interlayer design for Ti-6Al-4V and Inconel 718 Joining by ternary projection diagrams and thermodynamic calculations. Due to the fact that non-equilibrium solidification happens in additive manufacturing processes, therefore classic Scheil-Gulliver and Scheil-Gulliver were investigated, and their ternary phase projections with potential interlayers were plotted. By considering the ternary feasibility diagrams of titanium, nickel, as the base materials and different interlayers, appropriate interlayers were selected to join Ti-6Al-4V and Inconel 718. The findings of this research reveal that implementation of this approach for additive manufacturing processes can pave the way for designing additively manufactured multi-metallic interlayers in dissimilar joining or FGM materials.