Considering that many Nigerian roads are untarred, the effect of frequent plying of these untarred roads on passengers and the expected performance of suspension system of vehicles are important for health and safety reasons. This is significant because the transmission of vibration associated with suspension systems are dependent on the frequency spectrum of the road input, and the nature of the suspension system and the vehicle seating arrangement that is producing the vibration. Thus, this study focuses on the discomfort experienced by passengers based on parametric study of vehicle with semi-active suspension system under transient road conditions. The modeling of the of semi-active vehicle suspension system properties are contrived on the mass- spring damper system for 4 degree-of–freedom half- car model integrated with 3 degrees of freedom human-seat arrangement. Using vehicle parameters, the severity of ride discomfort experienced by the passenger as the vehicle traversed transient road conditions (i.e., traversing obstruction) was evaluated in terms of the vibration dose value (VDV). Results of simulation based on the parametric studies are presented and the vibration dose values evaluated to show the dependence of vehicle ride comfort on the characteristics of the various elements of the vehicle suspension such as stiffness and damping characteristics. The result showed that the variation of sprung mass and suspension stiffness of the vehicle had more significant effects on passenger discomfort than the variation of the unsprung mass. The parametric study also revealed that suspension stiffness affects the suspension working space as the vehicle traversed transient road condition.
In this work, Laplace transform-Legendre-wavelet collocation method is adopted for a semi-numerical analysis of predicting transient nonlinear behaviour of a radiative-convective fin with temperature-variant internal heat generation. The verification of the results of the hybrid method shown good agreements with the direct numerical and approximate analytical method s in previous works. Parametric analysis depicts the significance of the model parameters in a way that it is found that as the convective-conductive and radiative-conductive parameters increase, temperature distribution decreases in the extended surface. The thermal distribution is augmented in the passive device as thermal conductivity is amplified. At the different positions in the fin, the temperature is enhanced as time progress. The semi-numerical solution provides a very good platform for the predictive analyses of the extended surfaces.
This paper demonstrated the computational efficiency and accuracy of method of lines for the nonlinear transient thermal response analysis of a radiative-radiative porous fin with temperature-dependent internal heat generation under the influence of magnetic fields. To establish the computational accuracy of the method, the results of the solution are compared with the results of the developed exact analytical method. Also, the numerical solutions through the method of lines are adopted to explore the impacts of the model parameters on the performance of the passive device. It is found that as the conductive-convective, conductive-radiative, and magnetic field parameters increase, the fin temperature distribution in the fin decreases. The temperature distribution in the fin increases through the ?n as the nonlinear thermal conductivity parameter increases. It is hoped that the present study gives a good insight into the nonlinear analysis of the extended surface which will aid the proper design of the extended surfaces in thermal systems.
Throughout the oil industry, vertical pipes are used to convey crude oil either offshore from the bottom of the sea or onshore from the depths under the soil. These pipes, otherwise called risers, are attached to a platform at one end and buried under the sea bed or in the ground at the other end. The stability of these pipes is the subject of this investigation. The history of such analysis dates back over five decades when the vibration and stability of fluid conveying Trans-Arabian pipeline network was first studied; albeit for an on-shore environment. For that case, it was found that instability of the flow can be induced by vibration and that if such a horizontal conveyance pipe is supported at both ends, it bows out and buckles when the flow velocity of the conveyed fluid exceeds a critical value. Because of the industrial relevance of such conveyance networks, the problem has continued to generate interest over the years and especially now that deep waters offshore exploration is assuming increased importance in the Oil and Gas sector. When dealing with the stability of these pipes, most workers usually assume the Euler-Bernoulli hypothesis, which requires that plane sections perpendicular to the axis of the beam remain plane and perpendicular both before and after deformation. This essentially means that the deformation of such sections is neglected. However, the Timoshenko hypothesis accounts for such deformation by including transverse shear which is usually neglected. In this paper, the energy method is invoked to derive the governing equations including the effects of external temperature variation along the length of the pre-stressed and pressurized pipe. The stability of such pipes under plug flow model is thereafter presented.
Due to the influence of road roughness on all quantities representing dynamic response of vehicles such as vehicle ride comfort, tire dynamic force, dampers and spring forces, etc., the interaction between a vehicle and road profiles in relation to the comfort and health of passengers has become significant as road roughness causes a spectrum of oscillations for a moving vehicle. Thus, this study investigates the dynamic response of semi-active vehicle suspension system under the influence of steady state road conditions such as smooth, gravel and suburban roads to obtain mathematical equations based on the pitch and heave motions of the vehicle. Power spectral density, PSD, was used to characterize the road input spectrum on the basis of the road roughness parameters which correlate with International Roughness Index, (IRI). Vehicle suspension system responses to the different road inputs were obtained by simulation based on the mathematical model developed using Matlab/Simulink software. The root-mean-square acceleration was used as objective metric to estimate the passenger’s discomfort, dynamic tire force and suspension travel at a constant vehicle speed of 20 km/h while the ISO 2631 was applied to predict the discomfort experienced by the riders under different steady state road irregularities. The discomfort experienced by the riders on the gravel road and suburban road increased when the vehicle parameters were increased and also when the speed of the vehicle was increased. For smooth road, the riders experienced comfort according to ISO 2631, although the discomfort threshold increased with increase in speed of the vehicle but still within the threshold of human comfort zone. It can be concluded that for a vehicle ride within the human comfort zone on gravel and suburban roads, the speed of the vehicle should be brought down considerable below 20 km/h and the suspension systems should also be improved upon.
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