Research
Novel 3D Bio-fabrication Technologies
The purpose is enhancing tissue regeneration and implantable devices. Our group aims
at integrating state-of-the-art metallic, polymeric, and hybrid (the combination of
metal and polymer) additive manufacturing (AM) technologies. This research requires
multi-disciplinary expertise that can contribute to establishing novel 3D bio-fabrication
methodologies achieving the following long-sought characteristic features for many
implantable devices:
(a) Match the global anatomy of the specific patient.
(b) Integrate proper scaffold structure into the device to allow innate immune system
guided soft or hard tissue regeneration.
(c) Be capable of hosting therapeutic agents and stem cells with proper release mechanisms
to accelerate tissue regeneration.
(d) Possess soft and/or hard tissue mimicking mechanical properties.
(e) Biodegrade in a rate proportional to tissue growth to eliminate the chance of
body rejection in the long-term and the need for secondary revision surgeries.
As-built porous structure
Project coordinators: Gary Bowlin, Ebrahim Asadi
Process-property-geometry correlations for additively-manufactured Ti–6Al–4V
Material shrinkage is a major reason for part inaccuracy during the additive manufacturing (AM) process. Shrinkage is also a function of microstructure and microstructure is location/size specific. The dimensional accuracy model is used in designing high dimensional tolerance features for different devices in order to minimize the required subtractive post-processing of AM. The computational model is verified by a set of designed experiments and developed in as-built and heat-treated modes. In addition, it determines the necessity and impact of heat treatment on the material properties. Location/size-specific mechanical properties and microstructures establish a knowledge-based infrastructure to provide guidelines during finite element stress analysis of additively manufactured devices at Medtronic.
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Figures a and b show the top view of the designed geometrical features and images of the corresponding DMLS-manufactured parts. The practice to determine the dimensional features for some samples are shown in Figures c and d with a higher magnification. |
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Different microstructural phases of SLM-manufactured Ti6Al4V thin sheet. |
Publications:
Verification of Quantitative Phase-field Crystal Modeling of Materials in Solid-Liquid Coexistence Using NASA-PSI Experiments Data
Our central goal is to use NASA-PSI CSLM experimental data for verification and enhancement of a multi-time and length scale computational modeling framework and tool. The proposed multi-scale modeling framework is established around a novel and predictive computational material model (phase-field crystals, PFC), which is a unique computational model with the capability of simulating solid-liquid processes on diffusive time scales with atomistic resolutions. We calibrate the validated modeling framework for other binary systems to show the versatility of the proposed multi-scale modeling framework to simulate the coarsening phenomenon for other materials. In addition, we are capable of applying PFC method to identify and predict the microstructure evolution during the solidification in additive manufacturing process.
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Snapshots of the equilibrium solid-liquid interface model of the Pb-Sn calculated by the hybrid Molecular Dynamic (MD)/Monte Carlo (MC) simulation. The red and blue atoms are Pb and Sn, respectively. |
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Calculated phase diagram by the present MEAM potential along with experimental counterparts and ab-initio-aided CALPHAD calculations. |
Publications:
3D-printed Tablets and Pills
The objective is to explore the viability of using innovative 3D-printing technology for custom dosage and porosity of tablets and pills as an alternative biologistic method using interdisciplinary research in transportation and materials/manufacturing. Traditionally, tablets and pills are made from powders in the manufacturing site of pharmaceutical companies, transported in a controlled environment to pharmacies, and distributed between patients in need based on prescriptions. We propose to explore the viability of using a 3D-printing technique called Laser Engineered Net-Shaping (LENS) for 3D-printing of drugs. This technique can be used at the drug store to prepare drugs directly.
Project coordinators: Ebrahim Asadi, Sabya Mishra
Restoring Damaged Metallics Parts of Robots, Autonomous Vehicles and Drones (RAVD)
Laser Engineered Net-Shaping (LENS) can be used for fixing the damaged parts without disassembling them. LENS uses Nozzles to spray powders to the desired location where a focused laser beam creates a melt-pool to fuse the powders to the substrate and to each other. As it is apparent from LENS process, a cyclic heating and cooling occurs around the melt-pool and as a result in the part and, also, the whole RAVD system. The cyclic thermal treatment may cause: 1) overheating of other parts of the RAVD that do not have sufficient thermal resistance and 2) residual thermal stresses that may cause the catastrophic failure of the system at the next working cycles. We propose to develop a Multiphysics finite element method (FEA) that combines heat transfer, mechanical equilibrium (including solid-liquid transitions), and Maxwell's wave equation (for modeling laser) for this purpose. The proposed computational framework and tool enables the prediction of the temperature map and residual stresses to explore the feasibility of using LENS process for rapid repairing of the damages in specific RAVD systems; thus, developing proper standards for LENS use in RAVD systems.
Selected Publications:
1. S. Alireza Etesami, M. Laradji, E. Asadi, Transferability of interatomic potentials
in predicting the temperature dependency of elastic constants for titanium, zirconium
and magnesium, (2019). doi:10.1088/1361-651X/aaf617.
2. R.V. Perrone, J.L. Williams, Dimensional accuracy and repeatability of the NextEngine
laser scanner for use in osteology and forensic anthropology, J. Archaeol. Sci. Reports.
25 (2019) 308–319. doi:10.1016/J.JASREP.2019.04.012.
3. B. Fotovvati, S.F. Wayne, G. Lewis, E. Asadi, A Review on Melt-Pool Characteristics
in Laser Welding of Metals, (2018). doi:10.1155/2018/4920718.
4. Mark F. Horstemeyer, Integrated computational materials engineering (ICME) for
metals : concept and case studies, 2018.