Abstract- The main purpose of extended surfaces called fins to increase the heat transfer rate. Fins offer an economical and trouble free solution in many situations demanding natural convection heat transfer. The selection of a particular fin configuration in any heat transfer application depends on the space, weight, manufacturing technique and cost considerations as well as the thermal characteristics it exhibits. Radial or annularfins are one of the most popular choices for enhancing the heat transfer rate from the primary surface of cylindrical shape. Different profiles have profound influence on the thermal characteristics ofannularfins. In the present study, a detailed work has been carried out to develop a finiteelement methodology to estimate the temperature distribution for steady-state heat transfer and thermal stresses induced by temperature difference in Aluminium finned-tube of the heat transfer equipment. Finiteelement method (FEM) was used to compute the temperature and the stress fields. An extensive study was carried out using ANSYS, a powerful platform for finiteelementanalysis. Results obtained were presented in a series of temperature and thermal stress distribution curves for annularfins with rectangular, trapezoidal and triangular profiles for a wide range of radius ratios. The stress distribution curve is optimum with trapezoidal fin with wide range of radius ratio. It was found that the radius ratio and fin profiles are the significant parameters affecting the temperature and thermal stress distribution in annularfins.
VI. E XPERIMENT S ETUP AND R ESULT D ISCUSSION In order to validate the simulation results, a magnetic adhesion system consisting of three N42 grade neodymium magnets arranged in N-S-N orientation was built and attached to a prototype climbing robot. The measured dimensions of the whole system are: robot length = 360 mm, robot width = 210 mm, height of the center of gravity = 15 mm, magnet length and width = 50 mm, magnet thickness = 10 mm, yoke length = 350 mm. Two yokes with thickness of 5 mm and 15 mm as shown in figure 16 (a) were used for better comparison. The gap between the magnet surface and climbing surface is critical as a small gap increases the adhesion force significantly. Therefore, the gap was kept to a minimum of 2 mm. The ability to pass obstacles has been considered to be of secondary importance since the aimed climbing structures are closely uniform. Each wheel is independently driven and a differential drive system is adopted to realize the turn. The wheel diameter is 63mm. Rubber wheel with polyurethane layer is chosen to increase the traction. The output torque and rotation of the motor are 2.16 Nm and 30 rpm respectively. The maximum speed of the robot is 6 meter per minute. The robot’s net weight is 2.23 kg and 3.68 kg when 5 mm and 15 mm thick yoke is used respectively. Therefore, the required force for sliding avoidance can be obtained as 46 N and 76 N for 5 mm and 15 mm yoked robot respectively byusing equation 3 and 4 when acceleration, a = 0.5 m/s -2 and wheel friction coefficient, µ = 0.5.
In this paper it has been seen that the maximum value of force transmitted by tyre to the body of vehicle through lower suspension arm. During braking and cornering lower suspension arm is subjected to high stresses because of that Failure of lower suspension arm of vehicle was reported. Plastic deformation and cracks were observed frequently during on road running of vehicle. Stress analysis was performed usingfiniteelement method. Reinforced models were proposed on the basis of result data. The finiteelementanalysisof component leads to a reduction of physical and expensive tests. Consequently, it was not necessary for the production of several prototypes. Further corrective actions that are modifications in design will be carried on the basis of results analysis.
Farm tractor is an off road vehicle, used as a portable machine to do various useful works such as farming, haulage, heavy earthmoving & transportation. An off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. Off road condition includes uneven agricultural field surfaces and bumpy village roads on which the tractor has to operate. These ground irregularities leads to unexpected loads coming on the tractor components  .Tractor trolley or Trailers are widely used for transporting agriculture product, building construction material, industrial equipments & many other types of goods. Many varieties are available in trailer and use of particular trailer depends upon the application. The main requirements of trailer manufacturing are high performance with longer working life and robust construction. Tractor trolleys used for transportation are manufactured in small to moderate scale industries. Though tractor trolleys are manufactured of various capacities by various industries, there is a variation in manufacturing methods. The axle of a tractor trolley is one of the major and very important component and needs to be designed carefully, science this part also experiences the worst load condition such as static and dynamic loads due to irregularities of road, mostly during its travel on off road. Therefore it must be resistant to tolerate additional stress and loads.
considered to be the principal component of flexible pavement rutting. Permanent deformation in asphalt layers is caused by an asphalt mixture that is too low in shear strength to resist the repeated heavy loads to which it is subjected. Asphalt pavement rutting from weak asphalt mixtures is a high temperature phenomenon, it most often occurs during the summer when high pavement temperatures are evident. Mixture factors that causing rutting including: (1) aggregate gradation, (2) aggregate absorption, (3) aggregate affinity for asphalt, (4) aggregate size, (5) coarse aggregate shape, (6) coarse aggregate texture, (7) fine aggregate shape (angularity), (8) mineral filler properties, (9) asphalt content, (10) performance grading, (11) plastic fines in the fine aggregate, (12) low air voids and (13) performance graded asphalts (Kirkner et al., 1996).
Another possibility is to use numerical procedure like the finiteelement method for predicting the behavior andperformanceof rubber damping device. In this paper will be presented results obtained by the FEM together with conclusions regarding the behavior of elastomeric bearings.
Skin-panels are widely used on the flight vehicle struc- ture, for example, the airfoil, rudder, and cabin, due to their light weight, fine aerodynamic configuration, and high structural efficiency. However, these structures are characterized by low normal stiffness. The skin-panel surfaces of hypersonic flight vehicles are exposed to severe aerodynamic, acoustic, and thermal loading in service. 1,2 These dynamic loadings cover a large range of exciting frequencies, which can include one or more natural frequencies of the panel-type structures. It is difficult to avoid resonance for the structures of aircraft fuselage, thin skins, and stiffened panels. Excessive
Engine mounts have an important function of containing firmly the power-train components of a vehicle. Correct geometry and positioning of the mount brackets on the chassis ensures a good ride quality andperformance. As an FSAE car intends to be a high performance vehicle, the brackets on the frame that support the engine undergo high static and dynamic stresses as well as huge amount of vibrations. Hence, dissipating the vibrational energy and keeping the stresses under a pre-determined level of safety should be achieved by careful designing andanalysisof the mount brackets. Keeping this in mind the current paper discusses the modeling, FiniteElementAnalysis, Modal analysisand mass optimizationof engine mount brackets for a FSAE car. As the brackets tend to undergo continuous vibrations and varying stresses, the fatigue strength and durability calculations also have been done to ensure engine safety.
Earthquakes demonstrate vulnerability of various inadequate structures, every time they occur. The lessons taught from the aftermath of earthquakes and the research works being carried out in laboratories give better understanding about the performanceof the structure and their components. Damage in reinforced concrete structures was mainly attributed to the inadequate detailing of reinforcement, lack of transverse steel and confinement of concrete in structural elements. Typical failures were brittle in nature, demonstrating inadequate capacity to dissipate and absorb inelastic energy. This necessitates a better understanding of the design and detailing of the reinforced concrete structures under various types of loading. An extensive description of previous studies on the underlying theory and the application of the finiteelement method to the linear and nonlinear analysisof reinforced concrete structures is presented in excellent state of-the-art reports by the American Society of Civil Engineers in 1982 [ASCE 1982]. The results from the FEA are significantly relied on the stress-strain relationship of the materials, failure criteria chosen, simulation of the crack of concrete and the interaction of the reinforcement and concrete.Because of these complexity in short- and long-term behavior of the constituent materials, the ANSYS finiteelement program introduces a three-dimensional element Solid65 which is capable of cracking and crushing and is then combined along with models of the interaction between the two constituents to describe the behavior of the composite reinforced concrete material. Although the Solid 65 can describe the reinforcing bars, this study uses an additional element, Link8, to investigate the stress along the reinforcement because it is inconvenient to collect the smear rebar data from Solid 65.
Finite-time thermodynamics (FTT) [6-18] is a powerful tool for analyzing and optimizing performanceof various thermodynamic cycles and devices. Some authors have performed the performanceanalysisandoptimization for various CHP plants byusingfinite-time thermodynamics. Bojic  investigated the annual worth of an endoreversible Carnot cycle CHP plant with the sole irreversibility of heat resistance. Sahin et al  performed exergy output rate optimization for an endoreversible Carnot cycle CHP plant and found that the lower the consumer-side temperature, the better the performance. Erdil et al  optimized the exergetic output rate and exergetic efficiency of an irreversible combined Carnot cycle CHP plant under various design and operating conditions and found that the optimal performance stayed approximately constant with consumer-side temperature. Atmaca et al  performed the exergetic output rate, energy utilization factor (EUF), artificial thermal efficiency and exergetic efficiency optimizationof an irreversible Carnot cycle CHP plant. Ust et al  provided a new exergetic performance criterion, exergy density, which includes the consideration of the system sizes, and investigated the general and optimal performances of an irreversible Carnot cycle CHP plant.
Abstract. In order to analyze and design insulation systems, numerical methods, such as the finiteelement method and the boundary element method, are intensively used. In particular, for poroelastic materials models based on the Biot-Allard theory, mathematical relations in a mixed formulation were developed using the structural displacement u and the fluid pressure p as state variables. In this work, the simulation of the absorbing performanceof poroelastic samples, as if placed in impedance tube, is carried out using coupled poroelastic and acoustic finiteelement models. The goal is to evaluate two methodologies in order to obtain the acoustic absorption response of foam materials found on typical insulating systems. For the first procedure, the porous material model is coupled to a waveguide using a modal expansion technique. For the second procedure, the full acoustic domain is solved using acoustic finite elements and the acoustic absorption function is determined by evaluation of the acoustic pressure field. A systematic comparison of the influence of waveguide modes on the absorption response in the frequency domain was made and the validity of the modal approximation in coupled acoustic-poroelastic analysis is discussed.
Structural optimizationusing computational tools has be- come a major research field in recent years. Methods com- monly used in structural analysisandoptimization may de- mand considerable computational cost, depending on the problem complexity. Therefore, many techniques have been evaluated in order to diminish such impact. Among these various techniques, Artificial Neural Networks (ANN) may be considered as one of the main alternatives, when com- bined with classic analysisandoptimization methods, to reduce the computational effort without affecting the final solution quality. Use of laminated composite structures has been continuously growing in the last decades due to the ex- cellent mechanical properties and low weight characterizing these materials. Taken into account the increasing scien- tific effort in the different topics of this area, the aim of the present work is the formulation and implementation of a computational code to optimize manufactured complex lam- inated structures with a relatively low computational cost by combining the FiniteElement Method (FEM) for structural analysis, Genetic Algorithms (GA) for structural optimiza- tion and ANN to approximate the finiteelement solutions. The modules for linear and geometrically non-linear static fi- nite elementanalysisand for optimize laminated composite plates and shells, using GA, were previously implemented. Here, the finiteelement module is extended to analyze dy- namic responses to solve optimization problems based in fre- quencies and modal criteria, and a perceptron ANN module is added to approximate finiteelement analyses. Several ex- amples are presented to show the effectiveness of ANN to approximate solutions obtained using the FEM and to re- duce significatively the computational cost.
The design variables can be continuous, as in Park et al. (2005), or discrete, as in Topal (2009). No unique optimum solution is usually obtained when minimum thickness is searched and the ply thicknesses are discrete variables, e.g. multiple of a basic layer thickness (Gurdal et al., 1999). In this case, it is often better to use a multi-objective optimization formulation (Marler and Arora, 2004; Silva et al., 2009; Walker and Smith, 2003). Usually, the weight of the laminate and another performance parameter is considered (Almeida and Awruch, 2009; Topal, 2009; Deka et al., 2005). When continuous nature is used to design variables a single weight function can be used. Although the discrete nature for design variables is in general a practice requirement the use of continuous treatment is important to investigate the behavior of the solutions in a free condition with respect this constraint.
Abstract— Bending deformation of a Flemion-based Ionic conducting Polymer-Metal Composites (IPMCs) upon applied high electric field across its thickness is dominated by non uniform hydration distribution induced by electro-osmosis and electrolysis of water. Especially, Carboxylic acid group in Flemion provide the membrane with specific features which will lead to the change of equilibrium hydration state and provide improved performance as actuator material, which makes it different from Nafion based on perfluorinated sulfonic acid group. In the present study, finiteelement formulation is conducted for the basic field equations governing electroche- mical-mechanical response of a gold plated Flemion actuator including the effect of non uniform equilibrium hydration induced by pH distribution due to electrolysis of water. Some numerical studies are carried out in order to show the validity of the present formulation.
In an automotive vehicle, engine produces the power which is transferred to the drive shaft. Chain drive is one of the commonly used drive train to transfer this power. Chain assembly consist of chain, driving sprocket and driven sprocket. The driving sprocket is connected to engine output shaft, which transfer power to driven sprocket by chain. Further this driven sprocket transfer power to drive shaft. Therefore in chain assembly driving sprocket has a chance for design andoptimization for weight reduction. Due to high power transfer and high speed of rotation, high stress induces in sprocket teeth, also high speed leads to the vibrations. Hence it is important to designand manufacture sprocket properly, also mounting of sprocket is important.
Extensive uses of composite materials can be found in wide range of engineering applications such as in aircrafts, naval ships, and other high performance applications. It has gained immense popularity in the last two decades due to weight-sensitiveness, high specific stiffness and exorbitant specific strength. Modeling of composite materials in terms of mathematics is complex due to the existence of two or more materials within a single domain. Twisted rotating graphite-epoxy composite shallow conical shell model (Figure 1) with low aspect ratio can be idealized as turbine blade. In the midst of all competitive advantages of composites, delamination is the most common feared mode of damage which may occur due to manufacturing defects or in- service overloading (e.g. low velocity impact). The delaminated composite laminated structures exhibit new vibration frequencies depending on the size and location of delamination. The presence of invisible delamination can be detected with the help of prior knowledge of natural frequencies for delaminated composite laminates. In order to ensure the safety of operation, a profound understanding of dynamic characteristics of composite laminates is essential for the designers.
Rail joints are removed from the track when they are about to fail mechanically. Several types of inspections of appropriate frequency leading to remaining service life estimation trends of the joints are essential to determine the optimum time to take the joints out of service. Before they fail mechanically from defects such as joint bar failure (bolt hole cracks), rail end break etc., rail end battering due to metal flow is treated by grinding. Plastic flow of rail materials across the end post may cause the failure of the electrical signalling system. Therefore railway track maintainers or signalling people grind or cut the flow off with an angle grinder or a disc saw. When bolts break or bend, they are replaced rather than change the whole joint as a complete unit. Epoxy failure is another mode of failure relating to the rail signalling system integrity. Whatever may be the case of failure, an accurate determination of the remaining life of the joint is necessary to take the joint out the track before any catastrophic failures. Static and dynamic analysisusing elasto-plastic material modelling and fracture mechanics give an indication of a life span and a standard can be defined to set a remaining service life that can be used to schedule the joint removal from the track.
Abstract - This paper illustrates the vibration analysisof flapping wing MAV, using FEM analysis. The wing is modeled using beam and membrane elements. The wing’s natural frequencies are computed by modeling the membrane as plate without pre tension and initial bending. Whole wing geometry is modeled and analyzed using eBeam26 and ePlate36 2 . The code for FEM analysisand finding the mode shapes is written in Matlab with the help of guide lines provided in reference-1. Aerodynamic loads used in the FEM analysis are derived from modified strip theory based on blade elemental analysis for semi-elliptical wing 3 . Moreover the wing is
All analyses were performed under linearly elastic axisymmetric conditions using quadrat- ic elements Q8, as shown in Figure 1. Vertical and horizontal stresses were computed in dif- ferent depths of the pavement structure and the results were compared with the ones obtained using Everstress and MICHPAVE systems, mentioned previously. Table 1 presents the results of vertical stresses (kPa) and it can be observed that they are very similar to the ones obtained using Everstress e MICHPAVE. It also should be noted that this agreement is even better with Everstress system. Probably, this difference is caused by the limitation of MICHPAVE sys- tem related to the mesh refinement. Moreover, MICHPAVE only uses quadrilateral linear elements. The vertical stresses distribution obtained by the proposed system is depicted in Figure 4.
normally been applied to pavement design in the past. Empirical pavement design must rely on relationships between observations of pavement performance, a scale that represents traffic, some gross indicator of material quality such as a structural coefficient, and the thickness of the layers.