13th International Conference on the Technology of Plasticity (ICTP 2021): General
Program Organizers: Glenn Daehn, Ohio State University; Libby Culley, The Ohio State University; Anupam Vivek, Ohio State University; Jian Cao, Northwestern University; Brad Kinsey, University of New Hampshire; Erman Tekkaya, TU Dortmund; Yoshinori Yoshida, Gifu University
Thursday 10:20 AM
July 29, 2021
Room: Virtual: Room E
Location: Virtual
Session Chair: Alan Luo, Ohio State University
Cancelled
A Study on Developing Advanced Design Formula for Heat Form Quench (HFQ®) of Complex-shaped Aluminium Panels: Nan Li1; 1Imperial College London
Hot Form Quench (HFQ®) is a disruptive hot forming technology, recently developed, to produce cost-effective, complex-shaped, high-strength aluminium panels. The objective of this study is to develop an advanced methodology to guide optimal design for manufacturability using HFQ® Technology, through tackling a cutting-edge design challenge in the automotive industry for creating battery boxes with deep corners for EVs. In this study, a demonstrator model is first designed. Then, experimental and numerical tests are carried out, based on aluminium alloy 6082, to obtain the correlation between design variables, as well as their relationship with forming parameters. As last, optimisation algorithms are implemented to explore the optimal design with maximum drawing depth and minimum bottom corner radii. The advanced formula and the understanding of the design challenges developed through this study will enrich the design guides for HFQ®.
Towards Room-temperature Forming of Magnesium Sheet Alloys: Renhai Shi1; Jiashi Miao1; Alan Luo1; 1Ohio State University
Magnesium (Mg) sheet alloys have been attractive to the automotive industry for structural and body panel applications. One major challenge for automotive applications of Mg sheet alloys is their limited formability at room temperature. Recently, a new Mg sheet alloy and a multi-stage homogenization process have been developed at OSU, using an integrated computational materials engineering (ICME) approach. The new alloy achieved a yield strength of 240 MPa, tensile elongation of 30% and Erichsen Index of 7.7 mm, promising room-temperature forming applications. This paper will provide an overview of this new alloy design and thermomechanical processing development based on computational thermodynamic and kinetic modeling followed by experimental validation. The paper will also discuss microstructure evolution, strengthening mechanisms and plasticity of this new alloy.
The Effect of Crystallographic Texture Gradients on the Mechanical Response of Aluminum Automotive Extrusions: Warren Poole1; Andrew Zang1; Yu Wang2; Mary Wells2; Nick Parson3; Mei Li4; 1The University of British Columbia; 2University of Waterloo; 3Rio Tinto Aluminium; 4Ford Motor Company
There is current interest is expanding the use of aluminum extrusions in automotive applications. A challenge for the use of aluminum extrusions is the gradients of mechanical properties found within extrusions which result from inhomogeneous deformation during extrusion. In this work, the effect of local variations of crystallographic texture has been characterized experimentally using electron back scatter diffraction (EBSD) maps. In particular, through thickness effects have been examined for AA3xxx extrusion alloys and the role of texture variations has been considered for idealized extrusions using a porthole die. This work has focused on alloys which are primarily unrecrystallized after extrusion. The deformation textures have been predicted using the velocity fields extracted from finite element method calculations as an input for crystal plasticity simulations using the visco-plastic self-consistent method. It is found that texture predictions and the resulting mechanical anisotropy can be modelled well for situations where the strain path is relatively simple, for example near the centre of the extrudate but it is more challenging to predict properties near the surface where the shear strains due to friction can be greater than a true strain of 10.
"Learning by Seeing": Estimating Metal Plasticity Parameters Using In Situ Observations of Cutting and Indentation: Harshit Chawla1; Shwetabh Yadav1; Gan Feng1; Dinakar Sagapuram1; 1Department of Industrial and Systems Engineering, Texas A&M University
We present a novel and highly efficient approach to solve the inverse problem of estimating plastic constitutive parameters of metals using high-speed imaging and in situ measurements of deformation fields in plane-strain cutting and indentation. Point estimates of best constitutive parameters are computed purely using optimization-based algorithms by minimizing the error between internal plastic work and the corresponding external work, without the need for expensive finite element simulations. A Bayesian statistical approach is also demonstrated for obtaining the posterior distributions of the parameters. Data from standard compression tests are used to validate the feasibility of this approach for inferring plasticity parameters of ductile materials, including copper, brass and low melting-point eutectic alloys. The talk will also address the effect of imaging-related parameters (such as noise, spatial resolution, frame rate) on parameter estimation, as well as possible extension of this approach to high strain rates (> 10^3 per second).
Phase-field Modelling of Ductile Fracture to Describe Edge Conditions in Local Formability Studies: Fabio Di Gioacchino1; John Speer1; Kester Clarke1; 1ASPPRC Colorado School of Mines
By introducing a diffuse crack representation that depends on the critical energy release rate and an intrinsic length scale, phase-field modeling of fracture provides the framework for the formulation of physically-based gradient damage models that can be efficiently implemented in finite element calculations. Recently, we used the open-source FEniCS finite element computing platform to implement a phase-field model of ductile fracture. Here, we simulate expansion tests of punched and machined holes in sheets of advanced high strength steels. The different hole-edge conditions are described using initial boundary conditions for phase fields of damage and accumulated plastic strain. The value of the intrinsic length scale thus controls the thickness of the shear affected zone. Predictive capabilities are assessed by comparison with experimental measurements of hole expansion ratios.
Deforming Nanometric Volumes at Large Shear Strains by AFM Scratching: Mert Efe1; Bharat Gwalani2; Jinhui Tao2; Tiffany Kaspar2; Arun Devaraj2; Aashish Rohatgi1; 1Energy and Environment Directorate, Pacific Northwest National Laboratory; 2Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory
Shear deformation can cause significant changes in the microstructures and textures of the deforming materials such as during solid phase processing (e.g. extrusion, friction stir processing, etc.) and material removal (e.g. cutting, grinding, etc.) methods used for manufacturing of components. While the shear deformation and associated mechanisms of microstructural evolution at the bulk scale are well known, effects of shear deformation at nanoscale remain unexplored. In this study, we demonstrate nanoscratching with an atomic force microscope (AFM) tip as a tool to impose large shear strains in nanoscale material volumes. With the AFM process parameters and tip geometry used in our study, nanoscratching of a single-crystal copper substrate resulted in heavily deformed chips and the sub-surface. The nanoscratching process showed characteristics analogous to bulk-scale machining. Deformation analysis, using approaches developed for bulk machining, indicated that the shear strain in the chips and subsurface was ~ 3.9 and 4.6, respectively. TEM examination of the chips and subsurface showed dislocation substructures, geometrically necessary boundaries and other defects akin to those seen in highly deformed bulk materials. However, the level of microstructure refinement was somewhat lower when compared to the single- or polycrystal copper deformed to similar strains at the bulk scale, indicating possible role of the size effect of the nanoscale deformed volume in controlling the deformation behavior.