Papers by majid Baniassadi
Materials
A computational methodology based on supervised machine learning (ML) is described for characteri... more A computational methodology based on supervised machine learning (ML) is described for characterizing and designing anisotropic refractory composite alloys with desired thermal conductivities (TCs). The structural design variables are parameters of our fast computational microstructure generator, which were linked to the physical properties. Based on the Sobol sequence, a sufficiently large dataset of artificial microstructures with a fixed volume fraction (VF) was created. The TCs were calculated using our previously developed fast Fourier transform (FFT) homogenization approach. The resulting dataset was used to train our optimal autoencoder, establishing the intricate links between the material’s structure and properties. Specifically, the trained ML model’s inverse design of tungsten-30% (VF) copper with desired TCs was investigated. According to our case studies, our computational model accurately predicts TCs based on two perpendicular cut-section images of the experimental mi...
Macromolecular Materials and Engineering
Unmodified polyvinyl chloride (PVC) has low thermal stability and high hardness. Therefore, using... more Unmodified polyvinyl chloride (PVC) has low thermal stability and high hardness. Therefore, using plasticizers as well as thermal stabilizers is inevitable, while it causes serious environmental and health issues. In this work, for the first time, pure food‐grade PVC with potential biomedical applications is processed and 3D printed. Samples are successfully 3D printed using different printing parameters, including velocity, raster angle, nozzle diameter, and layer thickness, and their mechanical properties are investigated in compression, bending, and tension modes. Scanning electron microscopy is also used to evaluate the bonding and microstructure of the printed layers. Among the mentioned printing parameters, raster angle and printing velocity influence the mechanical properties significantly, whereas the layer thickness and nozzle diameter has a little effect. Images from scanning electron microscopy also reveal that printing velocity greatly affects the final part's quali...
Mathematics and Mechanics of Solids
Numerical prediction of osteoporosis evolution is a challenging objective in medicine, particular... more Numerical prediction of osteoporosis evolution is a challenging objective in medicine, particularly when one desires to account for patient dependency. The use of statistical methods to reconstruct bone microstructure distribution could be a helpful tool for this prediction, as they are able to provide different types of microstructures that can be optimized to fit with each patient. An initial bone sample was obtained from high-resolution X-ray computed tomography (HRμCT). Its microstructure evolution in time using a previously developed degradation model was used as the ground truth. Statistical bone microstructures were reconstructed at different stages of this evolution using two-point correlation functions (TPCFs). A blind search approach is used to find the optimized statistical microstructures, and the optimized coefficient showed less than 2% TPCF error between the statistical reconstruction and the degraded model. The statistical models also showed less than 13% error in th...
Frontiers in Bioengineering and Biotechnology
Due to the well-known biocompatibility, tunable biodegradability, and mechanical properties, silk... more Due to the well-known biocompatibility, tunable biodegradability, and mechanical properties, silk fibroin hydrogel is an exciting material for localized drug delivery systems to decrease the therapy cost, decrease the negative side effects, and increase the efficiency of chemotherapy. However, the lack of remote stimuli response and active drug release behavior has yet to be analyzed comparatively. In this study, we developed magnetic silk fibroin (SF) hydrogel samples through the facile blending method, loaded with doxorubicin hydrochloride (DOX) and incorporated with different concentrations of iron oxide nanoparticles (IONPs), to investigate the presumable ability of controlled and sustained drug release under the various external magnetic field (EMF). The morphology and rheological properties of SF hydrogel and magnetic SF hydrogel were compared through FESEM images and rheometer analysis. Here, we demonstrated that adding magnetic nanoparticles (MNPs) into SFH decreased the com...
Journal of Materials Research and Technology
International Journal of Pharmaceutics
A 3D microstructure of the non-woven gas diffusion layers (GDLs) of polymer electrolyte fuel cell... more A 3D microstructure of the non-woven gas diffusion layers (GDLs) of polymer electrolyte fuel cells (PEFCs) is reconstructed using a stochastic method. For a commercial GDL, due to the planar orientation of the fibers in the GDL, 2D SEM image of the GDL surface is used to estimate the orientation of the carbon fibers in the domain. Two more microstructures with different fiber orientations are generated and compared. The method is verified by comparing the commercial GDL (Toray TGP-H-060) model properties with other simulations or real GDL data. Three different reconstructed models are compared in terms of permeability, and the 3D pore size distribution of the models is also investigated. Through-plane (TP) and in-plane (IP) tortuosity, and the effects of binder addition on tortuosity are also discussed. For the TGH-H-060, tortuosity is derived to be 0.93, 1.50, and 1.42 in IP-x, IP-y, and TP-z directions, respectively. It is shown that adding binders to the fibrous skeleton increase...
Metals and Materials International, 2021
In this study, hydrostatic cyclic extrusion compression (HTCEC) is introduced as a novel severe p... more In this study, hydrostatic cyclic extrusion compression (HTCEC) is introduced as a novel severe plastic deformation technique for producing the relatively long and large ultrafine grained (UFG) and nano-grained tubes. In HTCEC technique, the utilization of pressurized hydraulic fluid between the piece and the die leads to the reduction of the friction force and the required processing load. All of these conditions facilitate the processing of the long and large tubes. Also, during HTCEC process, a movable mandrel is placed inside the hollow tube, which plays a main role in the reduction of the required hydrostatic pressure. To investigate the efficiencies of HTCEC process, aluminum 5052 alloy tubes were processed by HTCEC up to two passes. Then, the mechanical properties and microstructure evolution were examined. After the first pass of HTCEC, tangled and diffused arrangements of dislocations were formed. Then, the second pass of HTCEC resulted in a more refined and more homogeneous UFG microstructure with an average subgrain size of 636 nm, while the average grain size of the initial sample was ~ 360 μm. Tensile tests and hardness measurements revealed that two passes of HTCEC led to an increase in the yield strength from 98 MPa to 254 MPa (~ 2.6 times higher), the ultimate strength from 178 MPa to 306 MPa (~ 1.72 times higher) and the microhardness from ~ 56 to ~ 120 Hv (~ 2.14 times higher). Simultaneously, a decrease in the elongation to failure from 31.6 to 15.4% was observed, which is a small amount compared to the results of other studies. Also, in comparison to one-pass, a more homogeneous microhardness distribution through the thickness was detected in the two-pass processed tube. Fractography evaluations by SEM indicated that predominantly ductile fracture occurred in all samples. Furthermore, the equivalent strain and the pressing load of HTCEC process was evaluated by FEM simulation. It seems that HTCEC process, by utilizing its potentials, can produce the relatively long and large UFG tubes having a simultaneous high strength and good ductility.
RSC Advances
Graphical representation of the most determinant pore-lining side chains of Tb-MscL along with th... more Graphical representation of the most determinant pore-lining side chains of Tb-MscL along with the solid surfaces depicting the spatial shape of the interior pore.
Transport in Porous Media
3D reconstruction of heterogeneous materials from 2D images is essential for a precise characteri... more 3D reconstruction of heterogeneous materials from 2D images is essential for a precise characterization of their physical properties (mechanical, thermal, electrical and so on). For this, statistical descriptors such as two-point correlation function (TPCF), lineal path function (LPF), or two-point correlation cluster function (TPCCF) are frequently used. But the effective properties of the reconstructed microstructures are not always corresponding to the real ones as the statistical distribution functions may distribute the material microstructure in a different way from the original one. This is more pronounced for cellular and porous materials such as trabecular bone, fuel cell, and rocks where the connectivity between clusters is not well correlated to the one of real material and degrades the materials physical behavior predictions. This paper proposes a new statistical descriptor, called Quality of Connection function (QCF), able to determine the quality of connections between clusters and has detailed statistical information about the microstructure distribution. The proposed descriptor is tested on trabecular bone obtained from X-ray micro-computed tomography, and used as example of heterogeneous material having a complex microstructure. Effective properties such as Young Modulus were calculated for these microstructures and compared with real ones. The new descriptor shows improved capacity to describe the material microstructure distribution and prediction of its physical properties.
Applied RVE Reconstruction and Homogenization of Heterogeneous Materials, 2016
Polymers and Polymer Composites, 2022
Flame retardant (FR) additives may degrade polymers’ mechanical performance. In this work, FR epo... more Flame retardant (FR) additives may degrade polymers’ mechanical performance. In this work, FR epoxy composites fabricated based on two popular FR agents of ammonium polyphosphate (APP) and silica aerogel (SAG) are investigated. Several mechanical properties of these composites, including compressive, micro-hardness, and Izod impact, were investigated for different filler loadings. Although the addition of 10 vol.% APP improved compressive modulus, yield strength, and micro-hardness, it degraded the impact strength. The incorporation of SAG made the composites more ductile, improved the impact strength, but deteriorated their compressive properties. Samples containing both SAG and APP demonstrated synergetic effects evident by their enhanced compressive properties and hardness. The findings of this study can guide the design of epoxies with both exceptional FR and mechanical performance.
International Journal of Heat and Mass Transfer, 2022
In the present study, the effect of porosity on the cathode microstructure (50:50 wt. % LSM: YSZ)... more In the present study, the effect of porosity on the cathode microstructure (50:50 wt. % LSM: YSZ) of a Solid Oxide Fuel Cell (SOFC) has been examined. A 3-D finite element method for Mixed Ionic and Electronic Conducting Cathodes (MIEC) is presented to study the effects of porosity on cell performance. Each microstructure was realized using the Monte Carlo approach with the isotropic type of growth rate. The effect of porosity on the cathode of a solid oxide fuel cell involving the Three Phase Boundary Length (TPBL), electric conductivity of LSM phase, ionic conductivity of YSZ, mechanical behavior and tortuosity of the pore phase were explored in the present work. The cathode having a porosity value between 31 and 34% revealed the maximum TPBL value as well as a high variation in the electrical conductivity of the LSM phase. Pore phase tortuosity was also decreased by increasing the porosity factor.
Recently, various researches have revealed the importance of the investigations performed for eva... more Recently, various researches have revealed the importance of the investigations performed for evaluating mechanical properties and damages of the brain tissues while dealing with the production of surgical ligaments and helmets. Therefore, it is vital to study the structure of the brain both experimentally and numerically. By experimental tests, despite being costly, it is almost impossible to establish stress distribution in micro scale, which causes injury. Micromechanical predictions are effective ways to assess brain behavior. They can be applied to compensate for some experimental test limitations. In this work, a numerical study of the axonal injury in different heterogeneous porcine brain parts with different axon distributions under quasi-static loading is provided. In order to produce a heterogeneous structure, axons are distributed in regular, semi-regular, and irregular patterns inside the representative volume element. To accurately examine the brain tissue time-dependen...
Environmental Engineering Science, 2018
A 3D microstructure of the non-woven gas diffusion layers (GDLs) of polymer electrolyte fuel cell... more A 3D microstructure of the non-woven gas diffusion layers (GDLs) of polymer electrolyte fuel cells (PEFCs) is reconstructed using a stochastic method. For a commercial GDL, due to the planar orientation of the fibers in the GDL, 2D SEM image of the GDL surface is used to estimate the orientation of the carbon fibers in the domain. Two more microstructures with different fiber orientations are generated and compared. The method is verified by comparing the commercial GDL (Toray TGP-H-060) model properties with other simulations or real GDL data. Three different reconstructed models are compared in terms of permeability, and the 3D pore size distribution of the models is also investigated. Through-plane (TP) and in-plane (IP) tortuosity, and the effects of binder addition on tortuosity are also discussed. For the TGH-H-060, tortuosity is derived to be 0.93, 1.50, and 1.42 in IP-x, IP-y, and TP-z directions, respectively. It is shown that adding binders to the fibrous skeleton increase...
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Papers by majid Baniassadi
Higher order correlation functions must be calculated or measured to increase the precision of the statistical continuum approach. To achieve this aim, a new approximation methodology is utilized to obtain N-point correlation functions for multiphase heterogeneous materials. The two-point functions measured by different techniques have been exploited to reconstruct the microstructure of heterogeneous media.
Statistical continuum theory is used to predict the effective thermal conductivity and elastic modulus of polymer composites. N-point probability functions as statistical descriptors of inclusions have been exploited to solve strong contrast homogenization for effective thermal conductivity and elastic modulus properties of heterogeneous materials. Finally, reconstructed microstructure is used to calculate effective properties and damage modeling of heterogeneous materials.