Transactions of the Canadian Society for Mechanical Engineering
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Volume 40 (2016), Issue 4
A new type of incremental bending method for complicated curved sheet metal
Jiuhua Li, Xiaobing Dang, Kai He, Qiyang Zuo, Ruxu Du
A new type of incremental bending process for complicated curved sheet metal is proposed in the paper. The blank sheet is bended incrementally step by step. To validate the forming process, an incremental bending prototype is designed and manufactured, which was composed of a 3-DOF working table, a flexible supporting system and a 3D scanning system. The forming trajectory based on the theory of the minimum energy is planned according to the designed model of the sheet metal. Several experiments are carried out and the designed part is manufactured, which validated the proposed incremental forming method was successful.
Active heat dissipation system using adaptive recurrent wavelet neural network control
Yung-Lung Lee, Shou-Jen Hsu, Yen-Bin Chen
This paper proposes a novel cooling control system with the intelligent active technique, which is based on the NI-PXI systems structure combined with the heat pipe cooling chips. In order to further solve the controlling problems of nonlinear heat transfer system, the proposed intelligent system involves the PID control, traditional control, and the adaptive recurrent wavelet neural network controller (ARWNNC) control techniques. The traditional control there exists the undesirable control chattering, The PID control the Response of Control cannot be processed immediately and the input voltage saturation phenomenon, the adaptive recurrent wavelet neural network controller, is employed to approximate the ideal controller, while the corresponding parameters are derived by the gradient steepest descent method, thus being provided with the adaptive real-time control ability.
Analyses of energy absorbing device based on damped dynamic vibration absorber
Zhongqiang Zheng, Tao Yao, Peng Huang, Zongyu Chang
Vibrations exist widely in tall buildings, vehicle systems, and ocean platform suffering from environmental loading such as wind, wave or earthquake. With the global concern on energy and environmental issues, energy absorbing from large-scale vibrations becomes a research frontier. A type of damped dynamics vibration energy absorber is built and analyzed in this paper, in which an added mass is connected to the vibration system with the electromagnetic transducer and spring. The relationships between electrical damping ratio, excitation frequency ratio and dimensionless power are analyzed in frequency domain. The optimal parameters for maximizing the power output are discussed in analytical form while taking the inherent mechanical damping of the system into account. The results indicate that when the system has suitable optimal excitation frequency ratio and damping ratio and so on, more power can be obtained. It is helpful for the design of energy absorber devices.
Research on the frequency reliability sensitivity and reliability-based robust design of the random vibration system of continuous rod
Chunmei Lü, Yimin Zhang, He Li, Na Zhou
The frequency reliability sensitivity in the stochastic dynamic structure system and reliability-based robust design were studied deeply in this paper. With the criterion that the absolute value of the difference between natural frequency and forcing frequency, the frequency reliability method of avoiding resonance was proposed. Then frequency reliability sensitivity theory was presented, which provided a preliminary efficient way to analyze how each random parameter contributed to the system reliability. Moreover, the frequency reliability-based robust design method was obtained by robust and optimization technology on the basis of the frequency reliability and sensitivity research in the paper, which helped designers to establish acceptable parameter values and to determine the fluctuations of the parameters for the safe operations. Meanwhile, a numerical example of the random vibration system of continuous rod was provided and studied. The effectiveness and accuracy of the proposed methods were well demonstrated.
A new test method for shipping pallets of solar products
Shu-Tsung Hsu, Yean-San Long, Teng-Chun Wu
The photovoltaic (PV) industry is expanding rapidly to meet the growing renewable-energy demands globally. The failure-rate analysis indicated that a large portion of the accelerated PV module qualification failures were related to the failure of PV cell itself, which was leading to the yield loss of PV products during shipping or transportation. Therefore, the damaged cell (or module) caused by shipping is always one of the serious problems to impact the long-term reliability of PV product. This paper aims to propose a new test method of reliability evaluation for shipping pallet of solar product. The first scenario is the test pallet shipped in fab (e.g., fork-lift truck or hand-pallet truck). The second scenario is the test pallet transported from fab to fab by different vehicle (e.g., truck, train, aircraft, and shipboard). Consequently, detailed results were applied to SEMI Doc. 5431 and released as SEMI PV56-1214 by voting in December 2014. The solar cell/module/system makers and buyers, or any other party interested like package design, can thus have a common document to refer to when desired.
Hole problems in a circular piezoelectric plate
Yen-Chu Liang, Yun-Ping Sun, Lung-Nan Wu
Due to the unique electric-mechanical coupling effects, piezoelectric materials are widely used in sensors and actuators. Not only in smart structures but also in structural health monitoring, the developments of piezoelectric materials combined with the micro electro mechanical system (MEMS) techniques make our lives totally different. This paper provides a series of numerical simulations about the circular piezoelectric plate with a hole in the plate by using the special boundary element method (BEM). The Green’s functions of BEM are obtained from the derivation of extended Stroh formalism. By this formalism, the analytical closedform solutions of hole in an infinite piezoelectric medium under various loading conditions are obtained. The results demonstrate the coupling effects with different boundary conditions in the circular plate, which will satisfy the requirements of the designers who need to use the products with the hole in the piezoelectric circular plate.
Tooling design improvement of multistage cold forging of specialty shaped nuts using CAE and 3D printing
Shao-Yi Hsia, Yu-Tuan Chou
Given its critical role in the fastener industry, cold forging is widely performed in automotive production, manufacturing, aviation, and 3C products. Personnel experience and trying error approaches provide a subjective and unreliable background despite their extensive use in fastener forming and die design owing to the difficulty in controlling the development schedule. This study used DEFORM-3D analysis software to investigate the die service life from producing specialty shaped nuts in a multistage cold forging process. Effective stress, effective strain, velocity field, and other quantitative metrics of dies and work-pieces can be obtained from numerical simulations. Herein, 3D printing technology is also implemented to create cold forging dies and deformed work-pieces for assessing the dimension of tooling assembly. This process allows engineers to gain a better understanding of the tooling design at development phase and derives the parts, which were previously just simulation results from DEFORM-3D forming software. Results can help a multistage processing factory establish a cold forming capacity for the development of new products. Consequently, the ability of self-design and self-manufacture of specialty shaped fasteners in Taiwan could be increased widely to enhance the international competitiveness of domestic industries.
Effects of choke ring dimensions on thermal and fluid flow in a SRU thermal reactor
The effects of choke ring dimension on the thermal and fluid flow in a practical SRU (sulfur recovery unit) thermal reactor are investigated numerically. It is found that zone 1 is a higher temperature region. In contrast, zone 2 is a lower temperature region. The average temperature for the rich oxygen supply is higher than that of normal oxygen supply. Without a choke ring, the temperature difference between zone 1 and zone 2 is smaller and the temperature in zone 1 becomes lower while the temperature in zone 2 becomes higher. In addition, the average temperature in zone 1 and the sulfur concentration at exit are the lowest without a choke ring. The reactor with a choke ring height of 0.74 m has the lowest peak temperature and the largest sulfur concentration at exit. Finally, with a choke ring height of 1.11 m, the blockage effect of the choke ring leads to the largest peak skin friction coefficient.
Chimney-enhanced design applied on the thermal management of LED vehicle headlamp
Sheam-Chyun Lin, Yu-Cheng Chen, Yu-Chun Wu, Hung-Cheng Yen
LED vehicle headlamp consists of several high-power LEDs and thermal module inside an enclosed space, and locates near the high-temperature engine compartment. Certainly, these factors results in a challenging task on the thermal management of headlamp. Obviously, the temperature stratification inside this bounded region is an unfavorable phenomenon for the natural-convection thermal module. This study utilizes the chimney effect to achieve a more uniform temperature distribution and thus enhance the heat-dissipation ability. Firstly, an enclosed space is selected for executing the parametric study on the chimney geometry. Several effective alternatives are obtained and verified via both numerical and experimental means on the chimney design. Also, a significant 4:6°C reduction on LED junction temperature is attained on the best chimney-enhanced module. Then, these guidelines are applied to a commercial LED headlamp. Consequently, a range of 3:8 – 4:6°C decrease on LEDs is found for this innovative chimney thermal module.
Experimental study on tube jamming through a wedge-shaped hopper
Chih-Yuan Chang, Wei-Zhong Chen
A wedge-shaped hopper is frequently utilized as a tube feeder in the electric heater process. When falling from a wedge-shaped hopper, the tubes often form an arch near the outlet and stop the feeding process since a pile of tubes pass through a small hopper outlet one by one. This research aims to investigate the effect of process factors on the tube feeding process by applying Taguchi’s method and to design a wedge-shaped hopper that never jams. Chosen process factors are the wall angle of the hopper, outlet width of the hopper, number of test tubes, vibration strength of the vibrators and tube materials. Experimental results show that a large wall angle, a wide hopper outlet, a few tubes and a weak vibration are optimal settings. The wall angle and the outlet width of the hopper are more influential to reduce the jamming for all tube materials. A hopper that hardly jams can be designed by using optimum conditions.
Mechanical fault recognition research based on LMD-LSSVM
Zengshou Dong, Zhaojing Ren, You Dong
Mechanical fault vibration signals are non-stationary, which causes system instability. The traditional methods are difficult to accurately extract fault information and this paper proposes a local mean decomposition and least squares support vector machine fault identification method. The article introduces waveform matching to solve the original features of signals at the endpoints, using linear interpolation to get local mean and envelope function, then obtain production function PF vector through making use of the local mean decomposition. The energy entropy of PF vector take as identification input vectors. These vectors are respectively inputted BP neural networks, support vector machines, least squares support vector machines to identify faults. Experimental result show that the accuracy of least squares support vector machine with higher classification accuracy has been improved.
Nonlinear dynamic characteristics of magnetic shape memory alloy actuator
Zhi-Wen Zhu, Xin-Miao Li, Jia Xu
A kind of hysteretic nonlinear model of magnetic shape memory alloy (MSMA) is developed in this paper, and the nonlinear dynamic characteristics of a MSMA actuator are studied. Nonlinear differential items are introduced to explain the hysteretic phenomena of MSMA, and the magneto-mechanical coupled model of MSMA actuator in harmonic magnetic fields is developed. The relationship between input magnetic signal and output displacement is obtained, and the phenomena of the MSMA actuator’s accuracy aggravation in high-frequency magnetic field are explained. The theoretical and experimental results show that there are multiple frequencies in the response of the system, and the system’s motions change from periodic orbits to chaos with the increase in the level of the input magnetic signals; the multi-frequency vibration is induced by the hysteretic nonlinear characteristics of magnetic shape memory alloy.
Dynamics analysis, selection and calculation on the parameters of a rotary vibrating screen
Jing Jiang, Shuying Liu, Bangchun Wen
This paper introduces the structural characteristics and screening principle of rotary vibrating screen, and establishes nonlinear equations of rotary vibrating screen in view of the material effects. An approximate solution, material combination coefficient, and material drag coefficient for the nonlinear equations are solved by equivalent linearization method based on nonlinear theory. The selection and calculation on main parameters and a practical calculation example are carried out. It is of guiding significance and reference value for the design of this kind of machinery.
Dynamic behavior of a steel plate subjected to blast loading
Jong Yil Park, Eunsun Jo, Min Sook Kim, Seung Jae Lee, Young Hak Lee
This paper presents the results of an experimental test conducted on the blast resistance of a steel plate. A supporting steel frame on a concrete foundation was designed for testing a steel plate target against blast loading. A 1220 mm × 2140 mm × 10 mm steel plate was tested and subjected to the explosion of 50 kg of TNT (tri-nitro toluene) at a stand-off distance of 20 m. Data collected from the specimen included the strain and deflection of the steel plate. The test data were analyzed to evaluate the performance of the plate. The test results were compared with the results of Autodyn, which is a finite element method-based commercial software. The analytical results showed minor differences from the test results when the boundary conditions of the steel plate assumed that the upper and lower sides were fixed and the other sides were free.
Calculation of additional axial force of angular-contact ball bearings in rotor system
Zhenhuan Ye, Zhansheng Liu, Liqin Wang
Based on a loading-deformation relationship of bearing elements and the coordination of displacement between bearings in the rotor system, a model for calculating the additional axial force of angular-contact ball bearings in a single-rotor system is established. Nonlinear equations of this model are solved through the Rapid Descent method and Newton–Raphson method. The simulation results which are based on Gupta’s example verify that both the model and solving methods in this paper are reliable. A pair of 276927NK1W1(H) angular-contact ball bearings in symmetry in the single-rotor system is used as the example, calculation results of the additional axial force of bearings from the model in this paper and from the ISO method are compared and the influence of bearing geometry parameters and working conditions on the additional axial force is further studied. This model and its conclusions could provide the basic data and reference for analyzing the carrying ability and dynamic properties of rolling bearings.
A gear-shifting mechanism with a rotary configuration for applications in a 16-speed bicycle transmission hub
Yi-Chang Wu, Li-An Chen
A multi-speed bicycle transmission hub includes a geared speed-changing mechanism for providing different speed ratios and a gear-shifting mechanism for controlling the gear stage. This paper focuses on the embodiment design of a mechanical gear-shifting mechanism with a rotary configuration used in a 16-speed transmission hub for bicycles. A 16-link, five-degrees of freedom (DOF) split-power epicyclic gear mechanism, which consists of a gear differential and four sets of parallel-connected basic planetary gear trains, is introduced. Based on the clutching sequence table, a systematic design process is developed to come up with the embodiment design of the gear-shifting mechanism. A feasible and compact 16-speed rear transmission hub for bicycles is presented.
Structural analyses of water lifting devices with gears in ancient China
Kuo-Hung Hsiao, Yu-Hsun Chen
Gear mechanisms were wildly used in variety of purposes from the 2nd century BC in ancient China. There were several books with mechanical illustrations that described the structures and functions of gear mechanisms in ancient China. However, there has never been any record of their appearance or invention in ancient manuscripts. Since gear mechanisms can be used in changing the direction of the source power, some primary devices were added on gear train to transmit the power and generate the function of drawing water. Therefore, the water lifting devices with gears usually have similar topological structures. This work summarized authors’ research for the structural analyses of water lifting devices with gears that were described in ancient Chinese books. The historical development of gear mechanisms in ancient China is briefly introduced first. Then, in the viewpoint of modern mechanisms, the functions and components of water lifting devices with gears are analyzed and presented.
The systematic design of planetary-type grinding devices for optical fiber ferrules and wafers
Long-Chang Hsieh, Tzu-Hsia Chen
The traditional planetary grinding device can only polish one optical fiber ferrule. The other grinding device with donut polishing trace is also proposed for polishing wafer. This grinding device has a problem, that is, "the polishing qualities of different points on the wafer are not the same". Hence, this paper proposes a new planetary grinding device for polishing more optical fiber ferrules and more wafers. Based on the kinematics of planetary gear train, the equations of polishing trace and velocity are derived. Then, the velocity deviation percentage (Vdp) is calculated, which is an important design parameter. Area ratio (AR) is defined as polishing area divided by grinding pad area. The area ratio (AR) is another important design parameter for designing planetary grinding devices. In this paper, two design examples are used to illustrate the design process. The research results of this paper can provide an experience for the systematic design of planetary grinding devices.
Statistical analysis of constant-stress accelerated degradation testing with multiple performance parameters
Fu-Qiang Sun, Xiao-Yang Li, Tong-Min Jiang
For the long-life and highly-reliable product, accelerated degradation testing (ADT) method is an effective approach for evaluating life and reliability. However, most of previous researches have been focusing on the ADT method based on single performance parameter. The statistical analysis method of constant-stress ADT (CSADT) with multiple performance parameters based on Principal Component Analysis (PCA) and Support Vector Machine (SVM) is proposed in this paper. PCA is utilized to process the CSADT data in order to reduce the dimension of performance parameters. Then, SVM is applying in modelling the degradation process of the principal components. The engineering example proves that the method is feasible and efficient.
A self-calibration method for articulated arm coordinate measuring machines
Guanbin Gao, Jing Na, Xing Wu, Yu Guo
To improve the accuracy of articulated arm coordinate measuring machines (AACMM) and simplify the calibration process, an improved self-calibration method was proposed. Unlike the traditional calibration methods, which need external expensive precision instruments and elaborate setups, the proposed self-calibration method only requires a gauge to assist the data acquisition operation. By designing a movement trajectory of the AACMM, a series of joint angles can be obtained to form overdetermined equations based on the kinematic model of the AACMM. Therefore, the structural parameters of the AACMM can be obtained by solving the equations. Consequently, the calibration can be achieved by solving these equations. The coefficient matrix of the equations was further analyzed to simplify the equations, and a constructive method was presented to identify the structural parameters by solving the simplified equations with a modified simulated annealing algorithm, in which an optimized search strategy was applied to improve the robustness and efficiency. Experimental studies on an AACMM validate the convenience and effectiveness of the proposed AACMM self-calibration approach.
Swinging leg control of a lower limb exoskeleton via a shoe with in-sole sensing
Yanhe Zhu, Chao Zhang, Jizhuang Fan, Hongying Yu, Jie Zhao
A lower limb exoskeleton can help in weight-bearing and walking to assist laborers doing heavy work. For exoskeleton-assisted walking, the wearing comfort and walking convenience are important so there must be minimal interference with leg movement. Hence, a peculiar design strategy based on an in-sole sensing shoe is presented to achieve real-time motion detection and follow-up control of the moving leg. Compared to the elastic muscle extension, the sensor must exhibit minimal deflection under load. Therefore, an ultrathin structure integrating 6 bar linkages and 3 cantilevers has been used in the design of the in-sole sensing shoe which can detect force in two directions and torque in one. A swing phase experiment and a random leg motion test were carried out. Results show validity of human motion detection and follow-up control strategy based on this plantar surface sensor.
Performance analysis and improvement design of golf clubs
Cheng-Chi Wang, Tsui-Er Lee
Recently, golf has become a very popular sport, and most golfers focus on improving their skills and learning process. However, many researchers have studied and found that the hardness and vibration frequency of golf club, and the weight and angle of club head can result in unstable swing distance and accuracy. The golfers modify their swings attitude to adapt to the equipments, or even change the club set, and sometimes these situations cause sports injuries to golfers. Therefore, this study discusses how to design an optimal club set for individual golfers by customization and decreases the cases of sports injuries. The Taguchi method is applied to analyze and design the optimum club for shaft hardness, club head weight, spine and grip weight. The improved club is tested, and the result shows that the driving distance is increased by more than 10%, so that the maximum efficiency of hitting is increased. This study provides important reference for design of golf clubs.
Full journal title: Transactions of the Canadian Society for Mechanical Engineering
Abreviated journal title: Trans. Can. Soc. Mech. Eng.
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