Applied Mechanics and Materials Vol. 842

Abstract: In flying animal world, there are different flapping motions to produce lift and thrust depending on their species and size. Recent development in Unmanned Aerial Vehicle had tried to mimic flying animal. Rather than having two separate systems in providing lift and thrust, the wing upstroke and downstroke movement combined with wing twisting produce the necessary lift and thrust. Insects and some small birds have even the ability to fly hover.The present study is focused on the modeling of wing flapping motion. Instead of only accommodating flapping motion in a vertical plane and spanwise pitching motion, the model permits to include wing lead-lag motion in the horizontal plane. This more degree of freedom permit to model more complex wing flapping motion.

Abstract: In this paper, the dynamics of multiple-drive belt conveyors during starting is discussed. The aim of the research is to determine whether the belt sections in a multiple-drive belt conveyor can be viewed as a single-drive belt conveyor, and whether the DIN 22101 standard for the starting of a single-drive belt conveyor can still be used for the starting of a multiple-drive belt conveyor. A finite element model of a belt conveyor system was built in Matlab, consisting of a model of the belt and its support structure, and a model of the drive system. In this work, the simulations were carried out for the starting procedures of empty belt conveyors with varying number of drives. For each simulation case, the linear start-up procedure was tested. The simulations focused on the study of the axial elastic response of the belt. The simulations revealed that, by using more drives, the maximum belt stress during non-stationary as well as stationary conditions decreased. However, when using reduced starting times, negative stresses occur in the system. Overall, it was observed that the behaviour of each section between two drive stations in the multiple-drive belt conveyor differed from those of the single-drive belt conveyor. Therefore, the DIN 22101 guidelines for the start-up of a single-drive belt conveyor cannot be applied directly for the start-up of a multiple-drive belt conveyor.

Abstract: Published paper on modelling of propeller turbine blade and runner is not commonly found, especially those using Autodesk Inventor. One of them is titled CAD Modelling of Axial Turbine Blade using Autodesk Inventor. However, the road taken is quite complicated and should be repeated from the beginning whenever new geometrical characteristics of a new axial propeller turbine will be modelled. Currently, Autodesk Inventor has introduced the new tool that help sketching the spline lines either in 2D plane or 3D space simplifying the task of 3D modelling of propeller turbine blade, called Equation Curve. The Equation Curve tool requires the codes for creating the spline lines. To create the codes, two sources have been used: NACA report no. 460 and modelling methodology proposed by Milos in his paper. In NACA report no. 460, it is explained that NACA 4 Digit Series is created by combining mean line with the thickness variation curve of Gottingen 398 and Clark Y. This airfoil has 4 different lines with their own equation. The equations can be used for sketching in 2D plane. However, the solid model of the runner blade is formed from the airfoils in cylindrical surface. Then, as explained by Milos in his paper, the procedure is as follows: sketch the airfoil in 2D plane that is the tangent of cylindrical surface, move the airfoil to its center, rotate to its stagger angle, and project it to cylindrical surface. The result of this process will be the equations of lines in 3D space. Transform them to the Inventor codes. Input these codes to 3D Equation Curve tool to create the 4 lines for each cylindrical surface section of blade. Making the solid model of runner the following step is required: use loft command to create blade surfaces, use the stitch command to solidify, use the pattern command to create other blades, create hub, and lastly combine blades and hub. The solid model of the runner then is tested by simulating it using ANSYS Fluent. The hydraulic efficiency of the model is 85%.

Abstract: This paper aims to demonstrate how to model, mesh and simulate a hydraulic propeller turbine runner based on the geometrical specification of the runner blade. Modeling process is divided into preparation and implementation phase. Preparation phase illustrates how to develop stream surfaces and passages, how to create and transform meanline and how to create an rtzt file. The profile in rtzt file has a certain fix thickness which has to be altered later. Implementation phase describes operations necessary in creating a propeller runner model in ANSYS BladeGen which consist of importing rtzt file, modifying the trailing edge properties and altering profile thickness distribution to that of 4 digits NACA airfoil standard. Grid is generated in ANSYS TurboGrid utilizing ATM Optimized topology. CFD simulation is done using the ANSYS Fluent with pressure inlet and pressure outlet boundary conditions and k-ε turbulence model. Hydraulic efficiency of the runner is calculated utilizing Turbo Topology module in ANSYS Fluent. The authors will share the advantages that may be obtained by using ANSYS BladeGen compared with the use of general CAD Systems.

Abstract: This paper consists of the design and analysis of the strength of material composite of the fuselage of a Belly-Landing Mini Unmanned Aerial Vehicle (UAV). A belly landing UAV occurs when an UAV lands without its landing gear and uses its underside, or belly, as its primary landing device. Belly landings carry the risk that the UAV may flip over, disintegrate, or catch fire if it lands too fast or too hard [1], so the more important designs parameters for materials used are the specific strength and specific stiffness. Specific strength is defined as the ultimate tensile strength divided by material density, and specific stiffness is defined as Young’s modulus of the material divided by density [Franklin, 2010]. The aim of this Belly Landing Mini UAV is for used in situations where manned flight is considered too risky or difficult and no runway for take-off or landing, such as fire fighting surveillance, while the term 'mini’ means the design of this UAV has a launch mass greater than 100 grams but less than 100 kilograms [2], the objective of this project is the development and design of materials fuselage of a mini UAV with two layer sandwich structures made from composite materials and epoxy resin. For that purposes, 3 variations of the composite materials tensile test specimens have been manufactured in accordance with ASTM D3039 standard and tested its strength. The results showed that the fibre glass and fibre carbon composite with resin epoxy has the maximum tensile strength and Young’s modulus, so that the fabrication and manufacturing of the fuselage component is made by using that material composite. The Von Mises stress is used to predict yielding of materials under any loading condition from results of simple uniaxial tensile tests by using software Autodesk Inventor 2012. The results show that the design is safe caused the strength of material is greater than the maximum value of Von Mises stress induced in the material. The results of flight tests show that this small UAV has successfully manoeuvred to fly, such as take off, some acrobatics when cruising and landing smoothly, which means that the calculation and analysis of structure and material used on the fuselage of the Mini UAV was able to be validated.

Abstract: Hovercraft operates on multi-terrains such as on water surface, on roads, on mud, on non-flat surfaces... it is used popular on the world. With the ability of operating on multi-terrains at high speed, hovercraft is used for many purposes, such as on surveying and rescues missions on areas that are not reachable by normal vehicles, on military missions and traveling... Currently, methods for estimating hovercraft resistance are not accurate enough due to many experiential formulae and coefficients involved during calculating process. This paper presents a method for calculating hovercraft resistance using computational fluid dynamics (CFD) tools. This research method is used popular and modern research method on the world. The method was applied for calculating resistance of a 7 meters length hovercraft model. The modelling results give us suggestions in selecting engine power and operating speeds for minimizing fuel consumption.

Abstract: This study presents design optimization of rotor lock disc in the generator rotor which was analyzed by applying the respective lateral force taken from machine load calculation for a 2.5 MW permanent magnet direct-drive wind turbine generator. The machine load calculation result was derived from GH Bladed software output. The maximum tensile stress, internal stresses such as von Misses, maximum displacement and corresponding safety factor were calculated in terms of theoretical stress concentration factor due to discontinuity or change in cross-section in the region where the rotor lock is present. The rotor lock disc configuration was optimized to satisfy a safety factor of unity using exhaustive search method and Cosmos works software. Calculation results indicated that the safety factor of rotor lock disc with 40 mm thickness failed when design lateral force taken from the extreme load of rotor locking torque was used. However, the safety factor of the optimized rotor lock disc with 60 mm thickness has been improved when the inner radius and the total arc subtended angle are properly identified.

Abstract: Plate is one of the most common structural elements, which appears in a wide range of applications: steel bridges, blast-resistance door, and armored vehicles. In this paper, the behavior of steel plates under blast loading was studied through numerical approaches using LS DYNA and then the results were compared with the experiment results obtained from existing literatures. The study of a clamped square plate exposed to blast loading in three distinct stand-off distances. Three different methods of modeling blast loading were used, namely: empirical blast method, arbitrary Lagrangian Eulerian (ALE) method, and coupling of Lagrangian and Eulerian method. The empirical blast method was deployed by using key card *LOAD_BLAST in LS-DYNA. In ALE method, Langrangian and Eulerian solution were combined in the same model and the fluid-structure interaction (FSI) handled by coupling algorithm. In coupling method, the engineering load blast in LS-DYNA (*LOAD_BLAST_ENHANCED) was coupled with the ALE solver. In terms of central deflection and computational time, the coupling method appeared to be the best method which is very time-effective and showed a good correlation with the experiment data.

Abstract: Twin engines turboprop aircraft provides the most beneficial solution to meet the needs of short distance flight due to high fuel efficiency [1]. One of the emergency conditions which has to be considered for this type of the aircraft when one engine is out operating or one engine inoperative because it involves the safety of flight. Furthermore, a safe flight with one engine inoperative is regulated by FAR/CASR Part 25 and has to be complied during certification .Stability and control characteristics of a turboprop aircraft will change significantly if one engine inoperative condition occurs during cruise phase. The rudder and/or aileron deflections to counter the yawing and rolling moments due to the thrust of the operating engine must satisfy. Recognizing the importance of that consideration, this research will estimate the stability and control characteristics of lateral/directional in one engine inoperative condition on new turboprop 80-pax aircraft design concept.This paper presents procedures for estimating the lateral/directional static stability characteristics of a 80-pax turboprop aircraft during the conceptual design phase. The size of the rudder and aileron have to be iterated to fullfil the requirements at a condition when one engine is not operative. The rudder and the aileron deflections are estimated as functions of airspeed, roll angle, side slip angle and thrust setting. It will be shown in this paper that the required rudder deflection as well as aileron deflection can satisfy to balance the forces and moments due to asymmetrical thrust condition and the minimum control speed of the aircraft can be maintained as well.

Abstract: Among many methods of particle concentration in liquid, acoustic concentrator uses ultrasonic standing wave to concentrate microparticles in liquid. In order to determine its performance on particle concentration, estimation of acoustic energy density inside the concentrator is important since energy density is the main contributing factor in calculating the primary acoustic radiation force acting on the particles. The balance between the primary radiation force and hydrodynamic force acting on the particles inside the acoustic concentrator determine the performance of the acoustic concentrator. Therefore, this study focuses on the measurement of acoustic energy density inside the h-shaped acoustic concentrator and characterization of performance of the concentrator. First, energy density is estimated by curve-fitting the experimental particle position in the ultrasonic field with one-dimensional theoretical position. Second, two-dimensional acoustic and hydrodynamic fields are determined using two-dimensional simulation model in COMSOL Multiphysics. Integrating the governing equation for particle motion in the balance of acoustic and hydrodynamic forces result in the particle trajectory and it is compared with the experimental observation. The results would provide deeper insight into the operation of acoustic concentrator and the detailed phenomenon of particle motions inside the concentrator.