Applied Mechanics and Materials Vol. 889

Abstract: In the scope of this research, we shall examine the feasibility of applying an optimization method to ship propeller selection. The idea is to model the “traditional” selection process as a constrained optimization problem. Throughout this particular paper, an objective function (propeller performance) is optimized, subjects to a number of constraints imposed by cavitation, required propeller thrust, and available engine power. In the beginning, we select Wageningen’s B-series propellers as our study object because of its fidelity in experimental data, and, for the sake of simplicity, we shall use Sequential Quadratic Programming (SQP) method to solve the optimization problem. By introducing this new approach, we want to exploit the power of numerical machine to deal with a computational challenge; selecting a propeller not only best fits the design requirements but also in a most effective manner. Moreover, this method could be further developed, and be applied to the optimization of ship design.

Abstract: The chassis is the backbone of all automobiles. In passenger cars and buses, the chassis forms the basic shape of the vehicles and ensures the safety of passengers as well as transported goods. Most chassis have the frame structure and is manufactured using stamping and cold rolled technology to enhance the required rigidity. One of the most important criteria that chassis manufacturers consider during the design process is structural integrity: preventing failure while optimizing the use of materials. Traditional design methods requiring hand-calculations as well as experiments are less desirable because of the rising cost and time. Nowadays, with the development of numerical methods, computer capabilities and computer-aided engineering (CAE) overall, the design process has become much more efficient. This paper presents a procedure to simulate the complex dynamics of a 29-seat bus chassis using finite elements analysis in Ansys software. The results of this simulation are then used to verify the structural integrity of the chassis and support design optimizations.

Abstract: Computer numerical control (CNC) machine tool plays an extremely significant role in any manufacturing industry due to its automation and high accuracy. Keeping the CNC machine tool at its highest performance to meet the demand of high accuracy machining is always significant. To maintain the accuracy of a machine tool over the time, it is important to measure and compensate the geometric error, one of the main error source of machine tool, especially when the machine get old. There are totally 21 geometrical errors in a 3-axis machine tool including three translational errors and three rotational errors for each axis and three perpendicular error (Squareness) within three axes of the machine. This paper presents an economical and simple method for measuring the geometric error of a 3-axis CNC machine tool based on the machining of actual samples. Three samples for each axis will be machined following a design cutting path. The samples will then be measured using a coordinate measuring machine (CMM). The collect data will be used for estimating the geometric errors. The volumetric errors will be then computed and verified through machining of 3D geometries.

Abstract: The twin-screw vacuum pump is widely used in low and medium-low vacuum applications. Its core element consists of a pair of rotors rotating in opposite direction on parallel axes. Screw rotors with uniform pitch are usually finished by the form grinding method, but the rotors with variable pitch are not. In this paper, a manufacturing process for generating the tooth profile of the screw rotor with variable pitch by CNC lathe turning is proposed. The initial position of turning tool and normal profile error of the manufactured screw rotors are derived and verified numerically. Numerical examples are presented to validate the proposed method. The simulation results reveal that the proposed CNC turning process is feasible and flexible.

Abstract: This paper applies the stochastic finite element method (SFEM) to perform the natural frequency analysis of functionally graded material (FGM). It is assumed that the elastic modulus and width of the FGM beam vary along the thickness and width directions following exponential functions. The stochastic eigenvalue problem is solved independently by first-order perturbation and Monte Carlo simulation (MCS) method through changing elastic modulus as spatial randomness. The results show that the first-order perturbation method based SFEM produces a very close value to MCS method.

Abstract: One of the biggest environmental challenges of Vietnam is plastic wastes without recycling such as bottle, cans, plastic bag. The Vietnamese government have recognized these problems and called the reforming campaign to develop the sustainable technology to re-producing the wasted plastic. Thus, this research aims to contribute to deal with the issue by designing a plastic recycling machine. To satisfy domestic market of over 120 units at the first time, this research attempted to make a small machine at a low cost, but its throughput still reaches about 8kg plastic/hour and it can run within 16 consecutive hours a day. Hence, most of components is expected to be supplied by local vendors. As the result, the product price as well as maintenance cost is anticipated to be reduced. With the aim to produce the automated machine can incorporate continuous raw materials flow and at the same time move melted plastic in screw conveyor as defined by the regulation of the Programmable Logic Controllers (PLC) with timer to detect a velocity of melted plastic which come out from a nozzle of the screw conveyor and go to a mold. The hydraulic pressure, then, applies force to compressing and forming products. There are potential risks that can happen in fact, to deal with them. That is a reason Computer aid engineering and Finite element method modeling were conducted to make sure the force pressed in mold sufficiently and controlled the thickness of production as customer requirements.

Abstract: Measurement strategies for testing fuel tank corrosion using the ultrasonic Phased Array technology, these have been developed by companies producing ultrasonic measuring instruments, are only applied when performing manual measurement. Therefore, the applying of these measurement strategies for self-propelled robot carrying ultrasonic transducers to automate the testing process have not met the demand. This article presents the results of a study to develop a measurement strategy for testing fuel tank corrosion based on the specification of the self-propelled robot, the ability to build a corrosion map from collected image data by robot. Experimental results show that, with the three proposed measurement strategies using robot, the measurement strategy for moving the robot from bottom to top up will have the shortest testing time, image data are next and data coupling to build a corrosion map is easy. In addition, the process of building a corrosion map can be automatically performed on the computer, making the assessment process more convenient, accurate and faster.

Abstract: In this research, a new type of magneto-rheological brake (MRB) is proposed for small size motorcycle. The proposed MRB consists of a rotor with multiple trapezoidal teeth acting at multiple magnetic poles of the brake. In order to generate a magnetic field for controlling braking torque, a magnetic coil is placed on each side-housing of the brake. The inner face of each side-housing also has trapezoidal shape mating with the trapezoidal teeth of the rotor via MRF layer. By applying countercurrents to the coils, a magnetic fluid is generated with some magnetic flux going across the MRF layer (MRF duct) between the rotor teeth and their mating poles on the housing. By using multiple poles with trapezoidal shape, a high braking torque of the brake is expected while the size of the brake is still kept to be compacted. After an introduction about the development of MRBs in automotive engineering, the configuration of the proposed MRB is presented and its braking torque is derived based on Bingham rheological model of MRF. The proposed MRB is then optimally designed based on finite element analysis (FEA). Its optimized MRB is then manufactured and its braking performance is experimentally investigated. The MRB is then installed in a prototype motorcycle and the field test of this prototype motorcycle integrated with the MRB is then conducted.

Abstract: The paper is mainly focused on analysis characteristics of lobe pump with three different tooth profiles: Circular, Epi-cycloidal and Circular–Involute–Circular (CIC) rotor profiles. Based on the geometric analysis and mathematical model, the CIC rotor profile combined Circular–Involute–Circular is generated. In this paper, the CFD techniques are used to estimate the effects of tooth profile and lobe number to the pump performance. The simulation results obtained from FLUENT software illustrated that the rotor profile effects remarkably to the pump performance. The outlet pressure of CIC rotor profile is higher than that of the circular and epi-cycloidal rotor profiles. The numerical outcomes also showed that higher rotor’s speed is resulted in higher outlet pressure. Besides, the lobe number of rotor has effect slightly to the pump performance.

Abstract: Currently, the world has a lot of research and practical application of intelligent building systems integrated with intelligent power systems. Because Vietnam is a country with potential for solar energy, the integrator of solar energy is being strongly developed. However, the research result of the optimization of electrical energy used by the intelligent type solar integration is rare. This paper presents the design and structure of the module of intelligent control and monitoring via wireless network integrated with the automatic solar concentration system. The system allows easy connection and operation of all electrical power sources including the dispersal solar power to ensure the efficient and lower power consumption. In addition, the solar cell system is applied the Maximum Power Point Tracking technique (MPPT), which helps to stabilize and improve the power generation efficiency of the PV panels. The test results on the module showed absorption performance of automatic solar-cell flat plate systems is raised by 20-30% and power consumption in small households reduced approximately 30%.