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Item type:Publication, Armor Layer Uniformity and Thickness in Stationary Conditions with Steady Uniform Flow(2022-06-01); Negara, Arlendenovega S.The continuous movement of riverbed particles due to turbulent flow determines the stability of non-cohesive riverbeds and banks during riverbed and bank erosion and sedimentation. This study emulated the stable channel design by deriving the low maintenance cost of the channel through bed protection by an armor layer. The study investigated the effects of shear stress and grain size uniformity to determine the minimum non-cohesive armor layer thickness for the stability of riverbeds under steady uniform flow conditions. Experiments were conducted with four different discharges, five armor material gradations, and five bed-slope variations in a full-scale flume. We observed and recorded the behaviors of the five gradations of armor materials for given discharges and bed slopes. Eighty data points were recorded and analyzed. The hydraulic analysis of the flow along with the soil mechanics analysis of the armor materials was done. The soil mechanic analysis was particularly focused on the uniformity coefficient of the armor layer, C<inf>u</inf>, to derive the armor layer equation. However, for the manageability of the study, we set the limit of the Cu between 3.0 and 6.0. From the viewpoint of non-erodibility, a wider C<inf>u</inf> value indicated a thinner armor layer. Variables that govern the armor layer thickness and the layer thickness itself were derived and proposed. The variables, namely C<inf>u</inf>, shear stress (t<inf>0</inf> and t<inf>c</inf>), and mean diameter of the bed load and armor materials (D<inf>b50</inf> and D<inf>a50</inf>). Our results show that these variables governed the thickness of the armor layer, and this is expected to contribute to the design of stable natural channels, which can minimize the cost of irrigation canal maintenance and development. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Reliability-based Design Optimization of Classical Wing Aeroelasticity(2020-07-27); ; Bureerat, S.Flutter speed of aircraft is very important and needs to be firstly specified before a certification applied for a new aircraft by airworthiness regulator to make sure that the aircraft is free from flutter in its flight envelope. By assuming geometrical and physical parameters known, the speed is usually estimated from deterministic analyses in a design stage. In practice, some parameters are finitely measured by observing, especially for the geometrical parameters, material properties and so on due to the random in nature, which causes uncertainty of information often called uncertainties. The purpose of this paper is to combine reliability analysis and optimum design of aeroelastic aircraft wing. The classical two-dimensional wing with a typical airfoil section is used as an example in this study. To quantify uncertainty in the design of flutter speed, the discrete-time aero-elastic model and worst-case scenario are applied. Furthermore, the comparison between optimum design with/without reliability is provided in this study. The results show the proposed technique leads to the flutter speed being more conservative and realizable compared with the traditional technique.