Applied Mechanics and Materials Vols. 110-116

Abstract: The minimization of exergy destruction brings the design as closely as permissible to the theoretical limit. This study presents exergy destruction analysis of a turbojet engine for different flight Mach number and altitudes. Turbojet engine being considered consists of an inlet, a centrifugal compressor, reverse flow combustion chamber, axial-flow turbine and exhaust nozzle. The flight Mach number and altitude are examined on the exergetic destructions of compressor, combustion chamber, turbine and exhaust nozzle. The results of component-based destruction analysis are given as three dimensional exergetic-destruction response surface plots related to altitude and flight Mach number.

Abstract: Since the level of vibration always depends on the natural frequencies of the system, it is important to know the modal parameters of such system to control failure and provide prevention actions. However, for many mechanical engineering machines or structures, there is a demand and necessity to determine real-life modal parameters using actual operating condition. This type of testing condition cannot be done in lab environment because most of the mechanical structure is big in size and heavy. Thus, the purpose of this paper is to study the natural frequencies of a steel plate by using Operational Modal Analysis (OMA) and Ibrahim Time Domain (ITD). Comparison of results between both approaches will be shown.

Abstract: Analysis of transverse vibration of beams is presented in this paper. Unfortunately, complexities which appear in solving differential equation of transverse vibration of non-uniform beams, limit analytical solution to some special cases, so that the numerical method is presented. DTM is a numerical method for solving linear and some non-linear, ordinary and partial differential equations. In this paper, this technique has been applied for solving differential equation of transverse vibration of conical Euler-Bernoulli beam. Natural circular frequencies and mode shapes have been calculated. Comparing results with the cases which exact solution have been presented, shows that DTM is a strong method especially for solving quasi-linear differential equations.

Abstract: The interaction between wheel-rail produced defects on each other. Many studies of wear were done using pin-on-disc tribometer on interaction between the wheels – rail. The present paper proposes analytical study on wear. Wear rates were determined using depth of wear prediction on the interaction surfaces between wheel-rail. This prediction has been validated using pin-on-disc experimental technique using normal load of 100 N. The results show that the predictive equation developed can be used to predict the actual wear rate.

Abstract: Recently the truck industry has experienced a large push to overcome the increasing demands of higher performance, lower weight, and longer life of components, all this at a reasonable cost and in a short period of time. Conducting experimental test in the early stage of design is time consuming and expensive. In order to reduce the cost, it is important to conduct simulation using numerical methods by software to find the optimum design. In practice, many of the finite element objects are very large so it makes a difficulty in meshing and also in analysis of the model. It very takes time and need a lot of memory of computer. Submodeling technique offer the solution about that problem. This paper presents the submodeling technique that applied on the corroded truck chassis.

Abstract: In case of fault tree analysis of large complex system, the probability of bottom event in dynamic fault tree is uncertain in some cases. To address the problem, the paper presented a dynamic fault tree analysis method based on fuzzy set computation. The method separates logic attributes and timing attributes of dynamic logic gates. It can convert dynamic fault tree into static fault tree not considering timing constraints and obtain minimum cut set of static fuzzy fault tree with set operations, then the concept of minimum cut set is extended to dynamical minimum cut sequence. Thus, the dynamic fault tree was analyzed in both qualitative and quantitative aspects, which solve the problem that it is difficult to assign value of event probability in previously process.

Abstract: Inner Mongolia region is vast, and developable wind resource accounts for 50%. However, wind power grid has become the local wind development's main bottleneck. Therefore, studying the sustainability of wind power in this region has very important significance. This article from aspects of resource conditions, economic growth, wind power transmission, technical strength and policy environment analyzes the sustainability of Inner Mongolia wind power generation, then draws the conclusion that the bottleneck problem is expected to be solved and the sustainable development is expected to be realized.

Abstract: This paper provides presents the dynamic analysis and computer simulation results of electric vehicle (EV) powertrain performance systems. The generic simulation platform of an electric vehicle is developed using based on the SimPowerSystems/SimDriveline of MATLAB. Individual components of the model are constructed based on real vehicle data and mathematical dynamic model equations. The analytic results obtained from the mathematical modeling are verified with electric vehicle dynamics using generic simulation platform.

Abstract: This paper presents the stress analysis in optical fiber due to swelling of hydrogel material coated on it. The silica optical fiber was assumed to be coated by hydrogel that consists of hydroxyethyl methacrylate, acrylic acid and ethylene glycol dimethacrylate as crosslinker. The hydrogel swelling was modeled using free energy function. The conditional equilibrium of hydrogel was solved using finite element method and the stress induced in optical fiber was simulated simultaneously. The simulations were done for two hydrogel coating thickness values, 30 µm and 40 µm. Etched optical fiber coated by 40 µm hydrogel was also simulated. The results show that maximum stress in optical fiber is higher for thicker hydrogel thickness and is higher for etched optical fiber. Maximum stress magnitudes at all pH values are below tensile strength of optical fiber.

Abstract: This paper presents a design of wide input voltage range 2 kW flyback resonant converter for the wind turbine system. The propose converter design for operated under zero voltage switch, it could increase the efficiency of system by reducing the turn on switching loss. The advantages of this converter can be operated in a wide input voltage range, isolation and used a few devices. From the simulation result with PSpice software and experimentation results are conform together which shows the designed circuit can be operated under zero voltage with high efficiency and wide input voltage range (90-240V), by the simulation results can be used for the specified rate of power semi-conductor devices.