Olanrewaju Aluko - Academia.edu (original) (raw)

Papers by Olanrewaju Aluko

American Society for Composites 2022

This study applied computational molecular dynamics (MD) to model crystalline boron carbide (B4C)... more This study applied computational molecular dynamics (MD) to model crystalline boron carbide (B4C) using the Large-scale Atomic/Molecular Parallel Simulator software package. The Reax Potential Force Field was utilized at a strain rate of 107/s to evaluate micro-scaled mechanical behaviors of the material system. Then, the bulk– level (polycrystalline) behavior was evaluated using the relation between single crystal elasticity and the effective elastic behavior of polycrystalline materials. The simulations and analysis provide the link between the microscale and bulk-level performances of boron carbide, and the results at both length scales agree with the experimental data in the literature. The computational method can also be used to further develop strong and light-weight materials for aerospace, automotive, and military applications at relatively low costs of high-performance computational tools and higher throughput.

AIAA Scitech 2020 Forum

The results obtained from previously conducted molecular dynamics analysis of silicon carbide (α-... more The results obtained from previously conducted molecular dynamics analysis of silicon carbide (α-SiC (6H, 4H, & 2H-SiC), β-SiC (3C SiC)), silicon and boron nitride, were utilized as inputs in the MAC/GMC micromechanics software to model and evaluate the elastic properties of three-phase SiC/BN/SiC and four-phase SiC/BN/Si/SiC composites. This method of analysis eliminates the need for back-calculation of the apparent properties of the base constituents from the measured ceramic matrix composites properties. The multiscale models are validated against the available data in literature.

2010 Annual Conference & Exposition Proceedings

A pre-engineering program has been developed by The University of Michigan-Flint for high school ... more A pre-engineering program has been developed by The University of Michigan-Flint for high school students in the Lapper County Intermediate School District (LCISD) to motivate students" towards engineering or other STEM disciplines during their undergraduate study. A cohort of approximately twenty students from five different high schools was enrolled in four different engineering and computer science courses. These courses, offered at Lapeer Technology Center, provided a classroom environment similar to high school, using instructional materials relating students" prior knowledge of science and math that are relevant in engineering education. A survey questionnaire was used to evaluate students" backgrounds in science and mathematics, perception and motivation towards engineering, and whether the pre-engineering program motivated them towards engineering or other STEM disciplines. Classroom observation and changes in participation were also made during the courses, to evaluate the level of motivation. The number of students from the first year pre-engineering cohort that pursued engineering or STEM undergraduate education is also presented in this paper demonstrating the impact of the program.

An analytical model was developed to investigate the choice of failure criterion based on charact... more An analytical model was developed to investigate the choice of failure criterion based on characteristic length method for predicting composite joint strength. The available experimental data for joint strength in literature were used to determine the accuracy of analytically obtained results. The analysis utilized six failure criteria, where it was shown that among the failure criteria investigated no one gave a best fit for all the three plates evaluated for strength, and the fit of individual failure theories is variable from one type of material to another. The results also showed that the accuracy of this method can be improved by computing the average predicted values of more than three failure criteria.

American Society for Composites 2020, 2020

American Society for Composites 2019, 2019

© 2019 by DEStech Publications, Inc. and American Society for Composites. All rights reserved. Th... more © 2019 by DEStech Publications, Inc. and American Society for Composites. All rights reserved. The effect of strain rate and chirality on mechanical behavior of single walled carbon nanotube (SWCNT) and SWCNT/epoxy composite under tensile loadings was investigated using a computational molecular dynamics simulation and the Reactive Force Field. The analysis comprises the methodology employed to develop the molecular structures of SWCNTs and SWCNT/epoxy composites, the techniques for relaxing the materials systems, and the method utilized to characterize tensile parameters of the structures. The simulated results showed that the chirality of the SWCNTs as well as rate of deformation affect the Young’s modulus of both the SWCNTs and the SWCNT/epoxy composite

Volume 9: Mechanics of Solids, Structures, and Fluids, 2018

An analytical modeling was performed to investigate the effect of Nano filler on the mechanical p... more An analytical modeling was performed to investigate the effect of Nano filler on the mechanical performance of carbon fiber reinforced composite joints using the characteristic curve method. The joints were prepared from carbon fiber reinforced laminated plates with and without graphene nanoplatelet (GNP) and the characteristic dimensions used to determine the characteristic curve were evaluated from stress functions without experimental tests. The load-bearing capacity of the joints were carried out using different coefficient of friction and Yamada-Sun failure criterion along the characteristic curve. The evaluated results showed that the infusion of graphene nanoplatelet into the epoxy matrix of fiber reinforced composite plate increases the failure load of the composite joints.

Two-phase flow analyses are critical to successful design and operations of two-phase and multiph... more Two-phase flow analyses are critical to successful design and operations of two-phase and multiphase pipe flow applications found in major industrial fields, such as petroleum, nuclear, chemical, geothermal and space industries. Due to difficulties in obtaining analytical transient solutions, approximate solutions have been applied to two-phase pipe flow. However, these approximate solutions neglect convective terms in two-phase Navier-Stokes equations. The aim of this current study was to develop transient tools to predict transient two-phase pipe flow. The objectives of this study were to develop a simplified transient model and to validate the proposed model with published experimental data. A simplified transient two-phase pipe flow model was obtained in this study by simplifying the two-phase Navier-Stokes equations. The simplified equations include: (i) a transient continuity equation of combined two-phase flow that includes two new dimensionless terms; (ii) transient two-phase momentum equations that account for convective terms only; and, (iii) a steady state pressure gradient. Biographies OLUSOLA OLORUNTOBA r eceived his MSc degr ee in Offshore and Ocean Technology from Cranfield University in 2012. His areas of research are related to subsea engineering, flow assurance, and computational modeling.

A computational molecular dynamics model for determining the thermomechanical properties of EPON ... more A computational molecular dynamics model for determining the thermomechanical properties of EPON 862 and DETDA systems was developed using OPLS all atoms force field. The approach for building heavily cross-linked epoxy-based network is defined and presented. The simulations allowed thermal properties such as glass transition temperature and coefficient of thermal expansion; as well as elastic properties of the materials to be estimated. The results exhibited a good agreement with both available experimental data and simulated results in literature.

A computational molecular dynamic model involving multilayer graphene nanoplatelets in epoxy comp... more A computational molecular dynamic model involving multilayer graphene nanoplatelets in epoxy composite was developed in order to characterize its elastic behavior when subjected to thermo-mechanical loadings. In this investigation, the approach for constructing the molecular structure of graphene/epoxy composite using Optimized Potential Liquid Simulation (OPLS) force field is documented. Also, the cross-linking and the method for equilibrating the systems are defined. The techniques used for evaluating the models under different loading conditions are given. The predicted results are made available for the user of composite materials.

 Abstract— An analytical method for computing the stresses was developed to predict bearing stre... more  Abstract— An analytical method for computing the stresses was developed to predict bearing strength of pinned loaded composite joints using the characteristic curve model. Unlike conventional method that involved bearing test and both tensile tests to failure of notched and notched plates, the characteristic length in compression and tension that defines the characteristic curve was evaluated from stress functions without experimental tests. Two different graphite/epoxy laminates were used in the analysis to evaluate the joint strength for different joint configurations. The available experimental data in literature was used to validate the obtained results and the method of analysis was confirmed adequate by the good agreement between the experimental data and the analytical results.

American Society for Composites 2018, 2018

The effect of strain rate and chirality on mechanical behavior of single walled carbon nanotube (... more The effect of strain rate and chirality on mechanical behavior of single walled carbon nanotube (SWCNT) and SWCNT/epoxy composite under tensile loadings was investigated using a computational molecular dynamics simulation and the Reactive Force Field. The analysis comprises the methodology employed to develop the molecular structures of SWCNTs and SWCNT/epoxy composites, the techniques for relaxing the materials systems, and the method utilized to characterize tensile parameters of the structures. The simulated results showed that the chirality of the SWCNTs as well as rate of deformation affect the Young’s modulus of both the SWCNTs and the SWCNT/epoxy composite.

American Society for Composites 2021, 2021

The effect of size, shape, morphology, and arrangement of micro constituents of Boron Nitrite (BN... more The effect of size, shape, morphology, and arrangement of micro constituents of Boron Nitrite (BN) nanoplatelet/epoxy composites on their properties were investigated using a multi scale approach that includes Molecular Dynamics (MD) and micromechanics. The thermo-mechanical properties of the composites were evaluated using molecular theory and the analysis showed that the elastic constants of BN/epoxy composites were not severely affected by temperature. Also, the micromechanical analysis of Generalized Method of Cells (GMC) was utilized at higher length scale to evaluate elastic properties of the composites, for different geometries and arrangements of micro constituents. The predicted results of the analysis showed that the size, aspect ratios, morphology, and the arrangements of inclusions in BN/epoxy nanocomposites all have remarkable effect on the mechanical performances of the material systems.

Journal of Micromechanics and Molecular Physics, 2020

The geometric effect of single-walled carbon nanotube (CNT) on mechanical performances of epoxy n... more The geometric effect of single-walled carbon nanotube (CNT) on mechanical performances of epoxy nanocomposites was investigated under different loading conditions. The reactive force field (ReaxFF) and optimum liquid potential simulator (OPLS) were used in the computational molecular dynamics simulation. The analysis comprises the methodology employed to model the equilibrated structures of CNT/epoxy nanocomposites and characterizes elastic parameters of the structures. The computational results showed that the chirality of the CNTs affects the mechanical performances of the nanocomposites.

Composites Part B: Engineering, 2017

The elastic response of Graphene Nano Platelet/carbon fiber/epoxy hybrid composite was investigat... more The elastic response of Graphene Nano Platelet/carbon fiber/epoxy hybrid composite was investigated using multiscale modeling and analysis. The importance of volume fraction of graphene, GNP dispersion, and strain rates on the mechanical behaviors was determined. The analysis entailed the building of computational molecular dynamic model, involving multilayer graphene nano-platelets in epoxy composite, and micromechanical modeling. The predicted results show that the elastic responses of the hybrid composite increase with increased GNP volume fraction, dispersion, and strain rates.

Journal of Mechanics Engineering and Automation, 2015

The reactive force field was used to study the molecular dynamics of cross-linked EPON 862 (digly... more The reactive force field was used to study the molecular dynamics of cross-linked EPON 862 (diglycidyl ether of bisphenol-F) and DETDA (diethylene toluene diamine) system in order to predict its thermo-mechanical behavior under different loading conditions. The approach for building the EPON 862/DETDA structures, cross-linking, and equilibration of the systems, and the evaluation of the models are presented. The mechanical properties such as Young's and shear moduli, Poisson ratio, and yields strength as well as thermal properties such as glass transition temperature and coefficient of thermal expansion are predicted. The results are in close agreement with both experimental data and simulated results in literature.

Volume 9: Mechanics of Solids, Structures and Fluids, 2013

An analysis was performed to predict the failure load of unidirectional and woven pinned loaded c... more An analysis was performed to predict the failure load of unidirectional and woven pinned loaded composite joints using the characteristic curve model. The characteristic dimensions used to determine the characteristic curve were evaluated from stress functions without experimental tests. A parametric study was carried out for different coefficient of friction ranging between 0 and 0.15 to evaluate the effect of friction on joints failure using Tsai-Wu failure criterion along the characteristic curve. A comparison of analytical results with the available experimental data showed that the friction coefficient of 0.05 generally gave the best prediction for the joint configurations evaluated.

Composites: Mechanics, Computations, Applications, An International Journal, 2012

Volume 8: Mechanics of Solids, Structures and Fluids, 2012

An analytical solution is presented for determining the stress distribution in pin loaded composi... more An analytical solution is presented for determining the stress distribution in pin loaded composite joints using Lekhnitskii’s complex stress function approach. In this analysis, it is assumed that the pin is rigid, no clearance exists between pin and plate, and Coulomb friction is assumed to act throughout the contact region. The analysis also assumes that the contact boundary at the pin-plate interface spans through half of the hole boundary. The boundary conditions at the pin-plate interface are specified in terms of the trigonometric series used to represent the displacement field in the contact zone. Numerical results are presented for stress distribution in (±45°)s and (04°/±45°)s carbon fibers reinforced laminates.