Energy absorption characteristics of polyurethane composite foam filled tubes subjected to quasi-static axial loading

Foam-filled enclosures are very common in structural crashworthiness to increase energy absorption. However, very less research has been targeted on potential use of natural/recycled material reinforced foam-filled tubes. Therefore, an experimental investigation was performed to quantify energy absorption capacity of polyurethane (PU) composite foam-filled circular steel tubes under quasi-static axial loading. The thickness of the tubes was varied from 1.9, 2.9 and 3.6 mm. The tubes were filled with PU composite foam. The PU composite foam was processed with addition of kenaf plant fiber and recycled rubber particles that were refined at 80 mesh particulates into PU system. The density of PU resin was varied from 100, 200 and 300 kgm-3 . The PU composite foam-filled tubes were crushed axially at constant speed in a universal testing machine and their energy absorption was characterized from the resulting load-deflection data. Results indicate that PU composite foam-filled tubes exhibited better energy absorption capacity than those PU foam-filled tubes and its respective empty tubes. Interaction effect between the tube and the foam and incorporation of filler into PU system led to an increase in mean crushing load compared to that of the unfilled PU foam or tube itself. Relatively, progressively collapse modes were observed for all tested tubes. Findings suggested that composite foam-filled tubes could be used as crashworthy member

Numerical solution of the stagnation point flow and heat transfer with several effects

Problems related to boundary layer flow and heat transfer is important due to its various practical applications in engineering and industrial area. Cooling systems, nuclear reactor, electronic, hydrodynamics process, paper production and the boundary layer in liquid film condensation process are some of the example of various applications related to boundary layer flow and heat transfer. Present thesis solved numerically three problems of boundary layer flow on stagnation point over a stretching by considering the Newtonian fluid (viscous fluid) and non-Newtonian fluid (Williamson fluid). Besides, this thesis concern of the influence of slip flow, thermal radiation, magnetohydrodynamic (MHD) and viscous dissipation effects associated with constant wall temperature as boundary conditions. All gorvening equations in the form partial differential equations are transformed into ordinary differential equations by employing the suitable similarity transformation. The transformed ordinary differential equations obtained are solved numerically using a Shooting method in Maple software. Numerical solutions are obtained for the local Nusselt number and skin friction coefficient as well as the temperature and velocity profiles. The features of the flow and heat transfer characteristics for various values of eight pertinent parameters which are the Prandtl number, the stretching parameter, the Eckert number, the velocity slip parameter, the thermal slip parameter, the radiation parameter, the magnetic parameter and the nonNewtonian Williamson fluid parameter are analyzed and discussed. The comparison is also done by verifying through existing research so that the results obtained are a good agreement and reliable. As conclusion, the increases of Prandtl number, stretching parameter, dimensionless thermal and velocity slip parameter result to the decreasing in the wall temperature and also thermal boundary layer thickness. Meanwhile, increasing the non-Newtonian Williamson fluid parameter and thermal radiation parameter, the thermal boundary layer also increases

Flow And Heat Transfer Of Nanofluids At A Stagnation Point Flow Over A Stretching/Shrinking Surface In A Porous Medium With Thermal Radiation

In this paper, the effects of thermal radiation and viscous dissipation on a stagnation point flow and heat transfer over a flat stretching/shrinking surface in nanofluids are analyzed. The effects of suction/injection are also considered. Using a similarity transformation, the governing equations are transformed into a system of nonlinear ordinary differential equations. The resulting system is then solved numerically by Runge-Kutta-Fehlberg method with shooting technique. It is observed that the local Nusselt number increases with increment in the suction/injection parameter for stretching sheet whereas reverse effect is observed for shrinking sheet. It is found that skin-friction coefficient increases for both stretching/shrinking sheet with increase in volume fraction of the nanoparticles. © 2014 Elsevier Inc. All rights reserved

Flow and heat transfer of nanofluids at a stagnation point flow over a stretching/shrinking surface in a porous medium with thermal radiation

In this paper, the effects of thermal radiation and viscous dissipation on a stagnation point flow and heat transfer over a flat stretching/shrinking surface in nanofluids are analyzed. The effects of suction/injection are also considered. Using a similarity transformation, the governing equations are transformed into a system of nonlinear ordinary differential equations. The resulting system is then solved numerically by Runge-Kutta-Fehlberg method with shooting technique. It is observed that the local Nusselt number increases with increment in the suction/injection parameter for stretching sheet whereas reverse effect is observed for shrinking sheet. It is found that skin-friction coefficient increases for both stretching/shrinking sheet with increase in volume fraction of the nanoparticles. (C) 2014 Elsevier Inc. All rights reserved