Cracks are usually observed at the edge of materials deformed by accumulative roll bonding from conventional materials to nanostructure materials. The observed cracks then propagate in the materials during grain refinement. The cracks propagation affects the yield stress and the effective fracture energy of nanocrystalline materials. In this study, the impacts of crack propagation when measured as a function of grain size variants on nanocrystalline materials' yield stress are investigated for a material deformed by accumulative roll-bonding. The study employs experimental data and theoretical concepts of severe plastic deformation and cracks processes in nanocrystalline materials. The current studies also focus on nano-cracks that will not lead to rapid materials failure during grain refinement. The study revealed that crack propagation varied as a function of grain size variants during grain refinement. The study also revealed that nano-crack increased during the deformation of nanostructured materials. The study also revealed that the effective fracture energy decreased as grain refinement took place. The study revealed that nanomaterials yield stress decreased with the increase in effective fracture energy. The current study suggests a theoretical model that shows the generation of nanomaterials cracks during grain refinement as a function of grain size variants. In the model, the cracks propagate on nanocrystalline materials due to the compressive load applied to a material. The model predicts that the generation of cracks as functions of grain size variants impacts the energy level in nanocrystalline materials.

Engineers and scientists are faced with a major challenge of developing predictive models of nanoparticles scattering during membrane coating for efficient oil/water separation. Mechanical molecular simulation studies of key parameters or variable for structure/property correlations during nanoparticles coating are analysed on surface energy driven separability in the current study. The tools of stochastic process were used to study the random nature of nanoparticles scattering during membrane coating process using a specific coating technique.

Several filtration problem are reported in a centrifugal pump during operation in both domestic and industrial application. This problem have leads to membrane fouling that often leads to pump cavitation and other mechanical malfunctioning. Membrane technology were reported to be more promising in filtration process during centrifugal pump operation, though few problem of membrane fouling are still persisting which need further investigation. Critical parameters that affect membrane performance such as transmembrane pressure drop, pressure variation, density, flow of viscous fluid without impurities and flow of pure water was tested during modelling and simulation process. This was done to prevent the current problem of membrane fouling during pump operation. The design membrane simulated in this study was tested theoretically based on the experimental set up of a centrifugal pump. The testing and simulating process takes into account all physical parameters that affect membrane fouling during pump operation. The flow of pure water through the membrane was modelled theoretically using solid works and the major variables that impacted the separability was tested for optimal performance during filtration process without the occurrences of membrane fouling. The following facts were theoretically revealed by the simulated results. It was shown that a rapid decrease in flux was caused by concentration of polarisation during filtration process. It was also shown that membrane fouling increase membrane resistance and causes restriction to the transmission of the pure water and impurities during filtration. It was also revealed that the smaller the thickness of the membrane surface, the lower the rate at which the volumetric flux decreases during filtration. It was also shown that membrane viscosity increases with increasing pressure during performance. It was however revealed that pure water were able to be separated from impurities and the internal friction forces decreased during pump operation with little tendency of fouling being reported. It was also revealed that, although impurities were trapped on the membrane surface during pump operation, the higher resistance in the membrane surface the higher the possibility of membrane fouling during pump operation.

The strain rate effect of size variants on tensile behavior of aluminum after deformation by ARB was investigated. The yield strength, ultimate strength and tensile toughness for size variants were all observed to increase with increase strain rates at different ranges for the size variants deformed by ARB. Different results of deformation on yield strength for revealed for sizes variants. Different results for size variants on tensile behavior was also revealed for different strain rate during ARB. It was shown that yield stress generally increased with decreasing grain size since this was accompanied by dislocation motion from grain interiors to grain boundaries and subsequent dislocation pileups at the grain boundaries. It was also observed that in the directions where the grain sizes increased and subsequently decreased due to grain breakage (i.e. r1 and r3), there were more material flow in those directions, accompanied by more dislocation motions, dislocation pileups , and hence larger grain boundary curvatures in those direction. It was also shown that the material suffers a breakage of the laminar structure due to surface stress and strain that is generated during grain refinement on the TD, ND and RD. The critical condition of grain breakage occurs when the size of the grain is very small during grain refinement. The motion of dislocations is characterized by easy slip without any blockage inside the grain and this creates sub-cells that result in dynamic recovery.

In the current study the kinetic energy stored in a hydraulic shock absorber during damping is modelled theoretical. The theoretical model takes into account the relevant parameters that affect the kinetic energy of the damper during damping process. The fluid viscosity, density and temperature of the hydraulic fluid during damping is taken into consideration during modelling and simulation process. The kinetic energy harvested during damping process is revealed in the current study. The theoretical study was performed by simulating a twin tube damper system using the tool of SOLIDWORKS 2017-software. The physical behaviour of kinematics energy, density, viscosity and temperatures of fluid in the damping process was modelled theoretically. The following facts were theoretically revealed during the modelling process. It was shown that an increase in the system's velocity resulted to an increase in the system's Kinetic Energy. The results also revealed that even though the vehicle's mass is constant, the vehicle's Kinetic Energy is at its highest when the vehicle's dampers dampens vibratory oscillations at high velocities while transferring the energy of the spring motion to the damper whist ensuring ride comfort. It was also revealed from the pressure simulation results that the pressure difference between iterations 0-5(t) showed a large drop from iterations 5-40(t) and the pressure experienced fluctuations of maximum and minimal peaks until it stabilized during damping process. It was also revealed from the geometry of the damping system and fluid behaviour during damping operations that the drop in pressure is highly controlled by the resistance of fluid flow inside the damper. This resistance is caused by the change in geometry between the working cylinder and reserve cylinder as the fluid experienced change in velocities thus experienced turbulence as it entered and exit the change in geometry of the damper from the working cylinder to the reserve cylinder.