Fabrication of Polyurethane Based Fabric Composite Shaft and its Experimental Study Under Triple Point Bending

Semi-rigid urethane based fiber composite shafts are fabricated by high pressure injection molding process. The samples are made in Georgia Southern University’s laboratory where compressed air pressure is effectively used for this purpose. A special manufacturing process is suggested which can be used for mass production of these composites. This unique manufacturing technique creates a composite shaft with a core made of matrix material which is completely wrapped around by a woven fiber cloth with a very strong bonding between core and fibers. Three different types of woven fibers: fiber glass, Kevlar 49, and carbon fibers, are used. Triple point bending tests are carried out to test these three different types of composite samples and also samples made of only base or core material. During the test as the applied load is increased, a linear trend is observed between the load and mid-point deflection of the specimens up to a certain level. Higher load causes separation of fibers and core matrix and followed by local buckling of the separated fibers that are under compression region. This phenomenon brings down the bending stiffness of the composite significantly and it is quite pronounced in the load deflection curve diagram. Failure modes are observed to differ for each of these three types of composite and are discussed in details here. Composites with fiber glass wrapping are found to be the strongest among the three. Future work will involve determining the torsional and fatigue properties, and also the effect of fiber orientations on the mechanical properties of these composites

High Velocity Impact Properties Characterization of Nano-Phased Bi-Layered Body Armor

It has been already established by different investigators that addition of nano-reinforcements to plastics and fibers further enhances the mechanical and thermal properties of these materials. In this investigation, we have tested a bi-layer composite armor made of a ceramic layer and a nano-reinforcement infused epoxy layer. Our objective is to determine whether the infusion of nano-reinforcements in an epoxy layer enhances the ballistic properties of this bi-layer armor system. This bi-layered armor which was made of an alumina layer and a nano-infused epoxy layer was tested by a Fragment Simulating Projectile (FSP) method. Silica nanoparticles and multi walled carbon nanotubes (MWCNT) with a loading range of 0–1wt% were used for this purpose. Armors having the same thickness but made of only a single pure ceramic layer and a bi-layer composite made of a ceramic layer and a neat epoxy layer were also tested for comparison purposes. A gas gun with high velocity projectile was used to perform the experiment. A striking velocity of about 400m/s was used to hit the target armor plate. The striking velocity of the projectile was obtained by maintaining a breach end pressure of helium gas in the gas gun at about 500 psi. The striking velocity was chosen at a level which was well above the ballistic limits of the armor materials. A finite element analysis was also performed to evaluate the ballistic properties of the composite armor and to compare those with the experimental data. Numerical and experimental results for the residual velocity of the piercing bullets were found to be in good agreement. Details of the experimental and numerical data are presented in this paper

Numerical Investigation of Novel Design of Savonius Blade Geometries for Vertical-Axis Wind Turbines

With the increasing demand for clean, renewable energy sources, vertical-axis wind turbine (VAWT) research has gained considerable interest. The technology is primarily used for small-scale power applications in environments with unsteady wind conditions, such as urban locations. For this type of turbine the most important features are self-starting characteristics and energy conversion efficiency. For the Savonius type rotor, performance is increased by reducing drag losses on the advancing blades. The present study addresses the numerical verification of the performance of new designs for drag-driven VAWTs. Two new models were created using SolidWorks along with a standard Savonius model consisting of semicircular blades for benchmarking. All models were designed with the same swept area for comparison. 3D numerical simulation was completed using ANSYS FLUENT. Static conditions were first solved with a moving reference frame (MRF). The results from the MRF simulations were then used to initialize the transient solvers using sliding mesh models (SMM). 3D pressure distributions on the moving blades for each model were analyzed. From inputs of wind and rotational speed, torque values and coefficients of moment were reported. Each model was tested over a range of tip-speed ratios, and power coefficients were calculated. Results were compared to a standard Savonius VAWT, and increased maximum power coefficient was achieved with the new blade geometries

Adaptive Control of Synchronization for Muti Axis Motion System

This paper investigate on motion synchronization of multiple axes systems. Two different control strategies, a cross-coupling controller in feedback loop and an adaptive controller, were used to synthesize the synchronization compensator with the cross-coupling dynamics among the axes. By using these strategies, the asymptotic convergence of both tracking and synchronization errors are achieved. The comparison of the two controllers of the nominal plant is discussed. Experimental results of a three-axis motion system that include system uncertainties are also illustrated to verify the effectiveness of the proposed approach

Finite Element Analysis of Various Design Projectiles as Bullet Models

The objective of this research work was to perform a flow simulation around a running bullet and then compare and analyze three types of widely used bullet models. These are 7.62mm × 39mm, 7.62mm × 51mm, and 5.56mm × 45mm caliber popular NATO rounds respectively. Due to limited processing and computational resources, these bullet are modeled as cylindrical projectiles of similar length and diameter. Finite element analysis (FEA) are performed on these models using ANSYS explicit dynamics analysis code to investigate the effect of high velocity impact of these projectiles on a concrete plate. Three different types of meshing (coarse, fine, and fine with curvature) for each of these three cases have been used. Each projectile was fired at a different velocity. These velocities are selected in consultation withHornady Manufacturing, Inc which has done extensive research on these bullets. The selected firing velocities for 7.62mm × 39mm, 7.62mm × 51mm, and 5.56mm × 45mm caliber bullets are 2021ft/s, 2539.4ft/s 2706.7ft/s respectively. Overall, the simulation result of explicit dynamics clearly demonstrated cavitation and mushrooming of projectiles when impacting a 0.25 inch concrete plate. The 5.56mm × 45mm projectile seemed to have the largest overall total deformation values of 2.0303, 1.0487, and 0.26079 feet as obtained from simulation of the three types of mashing. This can be attributed due to the higher velocity (2706.7ft/sec) as compared to the other two cases. Similarly, the 7.63mm × 39mm has the highest average change of velocity of 144.7, 92.3, and 99.6ft/sec respectively from the three types of meshing among the three bullets which can be attributed due to its lowest impact velocity (2021ft/s)