Transactions of the Canadian Society for Mechanical Engineering
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Volume 39 (2015), Issue 3
Guest Editorial: Special Issue on Innovation and Application of Mechanical Engineering
Adaptive Sliding-Mode Control: Simplex-Type Method
The simplex method is easy and brief for designing the sliding mode, but it also has some disadvantages. Since the control vectors are constant, the chattering phenomenon also occurs when switching control takes place in simplex-type SMC scheme. Hence, we make few modifications to the simplex method that form an irregular simplex such that it improves the choice of simplex control vector and chattering phenomenon. The irregular simplex is obtained by an adaptive control law. The stabilization of a nonlinear multi-input system by using adaptive control based on simplex-type sliding-mode control philosophy is examined in this paper. The adaptive law and stabilization theorem are proposed and proved. The simulation results demonstrate that the simplex-type adaptive sliding-mode control proposed in this paper is a good solution to the chattering problem in the simplex sliding-mode control.
Improved Manufacturing Process for Movable Retaining Pins Using Optimization Method
Movable retaining pins are generally used in automobile gears, axles, crankshafts, and seatbelt assemblies. The original manufacturing procedures comprise three-stage forming and then drilling. However, a clamp in the drilling process always causes rod surface damage and dents, and the resulting depth tolerance that always exceeds specified dimensions. This study modifies the cold-forging process by replacing the original mechanical drilling stage with one additional forming stage comprised of backward extrusion. The finite element method is applied to analyze and simulate the forming load at each stage, and the Taguchi method is utilized to optimize the product quality in the key second stage. Analytical results show that transforming the original three forging processes and one drilling process into four forging stages overcomes the problems in part manufacturing. Simultaneously, the dimensional accuracy obtained from experiment and numerical analyses shows in good agreement and trusty.
Design and Analysis of CAM Mechanism with Translating Follower Having Double Rollers
The pressure angle is one of the primary considerations in designing a cam mechanism since an inappropriate angle may cause excessive sliding loads on the follower. This paper presents a simple yet straightforward method for the design and analysis of a cam mechanism with a translating follower having double rollers. In the proposed approach, conjugate surface theory is employed to derive a kinematic model of the cam mechanism. Analytical expressions for the pressure angle and principal curvatures of the cam profile are then derived. The validity of the analytical expressions is confirmed by machining a designed cam using a 3-axis CNC machine tool.
Development of 3-Speed Rear Hub Bicycle Transmissions with Gear-Shifting Mechanisms
Yi-Chang Wu, Che-Wei Chang
Rear hub bicycle transmissions require less maintenance and are more reliable than rear derailleurs. This study proposes a systematic design process for the conceptual design of 3-speed rear hub bicycle transmissions. By analyzing the kinematics of a basic epicyclic gear mechanism using the fundamental circuit method, the gear sequence and clutching sequence arrangements for 3-speed rear hub transmissions can be obtained. The numbers of gear-teeth for all gear elements resulting in a minimum installation space and satisfying the required speed ratio at each gear stage are determined. A gear-shifting mechanism is constructed to sequentially control the power-flow path within the epicyclic gear mechanism so as to provide three forward gears. An atlas of 3-speed rear hub bicycle transmissions is listed, where three devices are new design concepts and are suitable for further embodiment design. The results of this study will lead to the creation of new multi-speed rear hub bicycle transmissions.
Design, Fabrication, and Predictive Model of a 1-DOF Translational Flexible Bearing for High Precision Mechanism
Thanh-Phong Dao, Shyh-Chour Huang
Flexible bearing is significantly associated with high precision manipulators, actuators, and positioning stages. In this paper, a flexible bearing is designed for such applications. The life of a flexible bearing is very sensitively influenced by the stress concentration. The Taguchi method is applied to find the best combination of design variables to reduce the stress concentration. Multivariable linear regression (MLR) is established to model the relationship between the design variables and the stress response. In addition, to enhance the predictive efficiency for predicting, a radial basic function (RBF) neural network is used for this relationship. The effectiveness of all models is compared using statistical methods. It is evident that the relationship derived from RBF neural network is more accurate than that derived from MLR models. The confirmation experiments are conducted to verify the predicted results. The combined methodology in this paper is likely be used for various practical applications.
Embodiment Design of Novel 5-Speed Rear Drive Hubs for Bicycles
Yi-Chang Wu, Tze-Cheng Wu
This paper presents embodiment design of 5-speed rear drive hubs for bicycles. A 7-link, 2-degrees of freedom (DOF) compound planetary gear train as the main body of a rear drive hub is introduced. The relationship between the number of coaxial links of a planetary gear train and the number of gear stages that a drive hub can provide with is discussed. By means of kinematic analysis, four speed ratios of the planetary gear train are derived, which represents four forward gears of the rear drive hub. By adding a direct-drive gear, five forward gears can be provided and two feasible clutching sequence tables are synthesized. Manual translational-type gear-shifting mechanisms are further designed to incorporate with the planetary gear train for appropriately controlling the gear stage. The power-flow path at each gear stage is checked to verify the feasibility of the proposed design. Finally, two novel 5-speed bicycle rear drive hubs are presented.
Optimizing Design Parameters of a Novel PM Transverse Flux Linear Motor
Wan-Tsun Tseng, Chen-Nan Kuo, Li-Iau Su
In permanent magnet (PM) linear motors, the maximal thrust and the minimal cogging force are the most important goals to pursue. Design parameters of a PM linear motor such as translator pole pitch, magnet pole pitch, tooth width of the core, and magnet dimension can affect the thrust and the cogging force. In this paper, the relevant design parameters of the proposed linear motor are adjusted for the optimized performance of the machine. In order to obtain the optimal design parameters for achieving larger thrust and less cogging force, Taguchi’s method and grey system theory are adopted on the PM excited linear synchronous motor. From calculation of the signal-to-noise (S=N) ratio, the analysis of variance (ANOVA) and grey relational analysis, essential design parameters of the proposed linear motor can be found. These parameters are finally examined by using a finite element method (FEM) for 2D linear motor model simulations to corroborate the optimization results.
The Design and Meshing Efficiency Analysis of Helical Spur Gear Reducer with Single Gear Pair for Electric Scooters
Long-Chang Hsieh, Tzu-Hsia Chen, Hsiu-Chen Tang
To achieve reduced costs and energy conservation, this paper proposes non-standard helical spur gear reducer with one gear pair (having reduction ratio 19.25) to be the gear reducer for electric scooter. This paper also focuses on the meshing efficiency analysis of non-standard helical spur gear pair. According to Buckingham’s research, the theoretical meshing efficiency formula of non-standard helical spur gear pair is derived. Three design cases of non-standard helical spur gear pair (4,77) are proposed as examples for analyzing their meshing efficiencies at widely rotation speed range. The theoretical meshing efficiencies for the helical spur gear pair (4,77) are between 96.47–99.26%. Its best meshing efficiency occurs at 800–1000 rpm of pinion. The meshing efficiencies of these three design cases are almost same, and their differences are less than 0.5%. Considering the root strength of pinion, Cases II and III are better than Case I.
The Equation Derivation and Analysis of Meshing Efficiency for a Straight Spur Gear Pair
According to the concept of “Stribeck Curve” proposed by Downson, this paper proposes modified coefficients for the calculation of average friction coefficients for approach and recess. Based on the research of Buckingham, this paper derives the theoretical meshing efficiency equation of straight spur gear pair. And, based on the involute theorem, the average sliding velocities for approach and recess are obtained. The corresponding modified average friction coefficients for approach and recess are obtained. Finally, according to modified average friction coefficients and meshing efficiency equation, the meshing efficiencies for straight spur gear pair (15,79) are analyzed to be 99.04–99.62%. The best meshing efficiency occurs at pinion speed 800–1500 rpm. Based on the proposed approach, the meshing efficiencies of all spur gear pairs can be analyzed. The results of this paper will contribute to engineers in the design of straight spur gear reducers.
Seismic Response and Numerical Verification for a 1/25 Scaled-Down Reinforced Concrete Reactor Building Specimen
Wei-Ting Lin, Yuan-Chieh Wu, An Cheng, Hui-Mi Hsu
In recent years, full-scale specimens for seismic test were important to safety assessment of the structure in nuclear power plants but the full-scale tests were not easy to realize due to the limited capable of the existing shaking table capacity. In Taiwan, it was first time to construct a 1/25 scale-down reinforced concrete reactor building specimen in a nuclear power plant and conduct to study the dynamic properties using shaking table test. The specimen was with a length of 2.9 m, width of 2.9 m, height of 2.9 m and weight of 28 tons and cast using the non-demoulding technology and self-consolidating concrete. The entirety structure was composed of a primary containment (thickness of 10 cm), a secondary containment (thickness of 7.5 cm) and three floors (thickness of 30 and 15 cm). The comparison of measured and calculated results demonstrate that ETABS numerical model was satisfactory and can be further used for numerical shaking table tests and real life structures.
PIRAA: Development of an Injection Molding Machine Manufacturing Monitoring System Based on Production Information Retrieval Agent Architecture
Shang-Liang Chen, You-Chen Lin, Yun-Yao Chen, Sin-Ru Wang"
Production information retrieval is an important issue for manufacturing industries. Effective data transmission and retrieval mechanism with data protection is an urgent research topic. Therefore, a socket information retrieval mechanism and agent services for information retrieval on the basis of injection molding machines is proposed in this research and is addressed as Production Information Retrieval Agent Architecture (PIRAA). The proposed agent adapted a customized packet format for client-server connection communication and sent process parameters back to a production process database. Using the experimental results, a cloud-based platform was implemented based on injection molding machines. The results show the PIRAA framework can be used for developing cloud-based platforms in a stabilized and remarkable way.
Development of Tracking System for Mobile Robot Using Image Recognition Algorithms
Kuo-Lan Su, Bo-Yi Li, Kuo-Hsien Hsia
In this paper, an intelligent mobile robot using image processing technology is developed. The mobile robot contains an image system, a loading platform, a balance control system, a PC-based controller, four ultrasonic sensors and a power system. We develop a PC-based control system for image processing and path planning. The mobile robot can track a moving target and adjust the loading platform by the balance control system simultaneously. The image processing based on OpenCV uses two different tracking methods to track moving targets: MTLT (Match Template Learning Tracking) and TLD (Tracking, Learning and Detection). The efficiency of both methods for tracking the moving target on the mobile robot is compared here. The balance control system, with a HOLTEK Semiconductor Company’s HT66F Series 8-bit microprocessor as the processor, uses the PID control law according to the feedback signals of the inclinometer sensor to control the balance level of the loading platform.
Using Nonlinear Respiratory Mechanics to Optimize the Respiratory Signals under Eucapnic and Hypercapnic Conditions
Shyan-Lung Lin, Hsing-Cheng Chang, Yu-Zhe Tsai
In this study, the optimal chemical-mechanical respiratory control model was modified to include nonlinear respiratory mechanics with a lumped viscous resistance of the flow through the entire respiratory system, and a flow resistance that is proportional to the power of the flow rate. To evaluate the optimality of the system, a quadratic rising neuromuscular drive was applied to a neuro-mechanical effector and the respiratory signals were optimized under hypercapnia and eucapnia conditions. A continuous resistive load was imposed to compare the model behavior of respiratory mechanical loading with normal load. The optimized respiratory signals were demonstrated and the ventilatory responses with the optimized breathing patterns were examined. Our results showed that the nonlinear model acquired the intended level of ventilation with higher tidal volume VT and lower breathing frequency F during CO2 inhalation and lower VT and higher F during exercise.
Miniature Fluid Dynamic Bearing with Improved Load Capacity
Chien-Sheng Liu, Min-Kai Lee, Ying-Chi Chuo
In this paper a novel design is proposed to improve the load capacity of fluid dynamic bearing (FDB) for miniature spindle motors and small-form-factor data storage applications. In contrast to conventional miniature FDB with two sets of herringbone grooves on its inner surface, the proposed miniature FDB comprises another one set of herringbone grooves on its outer surface. The proposed miniature FDB is verified numerically utilizing commercial software Advanced Rotating Machinery Dynamics (ARMD). The simulation results show that compared to the conventional miniature FDB, the proposed miniature FDB can obviously improve the load capacity of the bearing system. Overall, the results presented in this study show that the proposed miniature FDB provides another solution for miniature spindle motor applications.
Aerodynamic Effect of 3D Pattern on Airfoil
Xiao Yu Wang, Sooyoung Lee, Pilkee Kim, Jongwon Seok
It is known from recent observations that the textured surface plays a role in reducing the drag force and increasing the lift force of a moving body. Comparing the numerical simulation between smooth surface and textured surface in this study, we also observe that the textured surface reduces the drag coefficient and increases the lift coefficient of the surface. As for the two simulation models performed in this study, we use the modified NACA0018 model for the basic airfoil configurations. After the simulation using Fluent, the results about the two models are mutually compared, and we found that the textured airfoils can decrease the drag coefficient and increase the lift coefficient dramatically. We also found that there exists an optimal angle, at which both the drag coefficient decrement and the lift coefficient become maximum. The final goal of this study is to design the airfoil with the reduced drag coefficient and the improved aerodynamic efficiency.
Power Law Fluid Model Incorporated into Thin Film Elastohydrodynamic Lubrication of Circular Contacts
Li-Ming Chu, Hsiang-Chen Hsu and Chia-Hsiang Su
The modified Reynolds equation for power-law fluid is derived from the viscous adsorption theory for thin film elastohydrodynamic lubrication (TFEHL) of circular contacts. The lubricating film between solid surfaces is modeled as three fixed layers, which are two adsorption layers on each surface and a middle layer. The differences between classical EHL and TFEHL with power-law lubricants are discussed. Results show that the TFEHL power law model can reasonably calculate the pressure distribution, the film thickness, and the velocity distribution. The thickness and viscosity of the adsorption layer and the flow index significantly influence the lubrication characteristics of the contact conjunction.
Stress Intensity Factors of a Semi-Elliptical Crack in a Hollow Cylinder
Shiuh-Chuan Her, Hao-Hi Chang
In this investigation, the weight function method was employed to calculate stress intensity factors for semi-elliptical surface crack in a hollow cylinder. A uniform stress and a linear stress distribution were used as the two references to determine the weight functions. These two factors were obtained by a threedimensional finite element method which employed singular elements along the crack front and regular elements elsewhere. The weight functions were then applied to a wide range of semi-elliptical surface crack subjected to non-linear loadings. The results were validated against finite element data and compared with other analyses. In the parametric study, the effects of the ratio of the surface crack depth to length ranged from 0.2 to 1.0 and the ratio of the crack depth to the wall thickness ranged from 0.2 to 0.8 on stress intensity factors were investigated.
Fault Diagnosis Based onLMD-SVD and Information-Geometric Support Vector Machine for Hydraulic Pumps
Ye Tian, Chen Lu, Zhipeng Wang, Zili Wang
This study proposes a fault diagnosis method for hydraulic pumps based on local mean decomposition (LMD), singular value decomposition (SVD), and information-geometric support vector machine (IGSVM). First, the nonlinear and non-stationary vibration signals are decomposed using LMD into several product functions (PFs). Then, the PFs are processed by SVD to obtain more stable and compact feature vectors. Finally, the health states are identified by an IG-SVM classifier, which is less-dependent on the selected kernel function and parameters than SVM. In addition, the comparisons between LMD, EMD, and WPD demonstrate the superiority of LMD in feature extraction. Compared with SVM and BP neural network, IG-SVM shows higher classification accuracy and computational efficiency in dealing with small-sample fault diagnosis. From the experimental results, it was concluded that the proposed method can effectively realize fault diagnosis for hydraulic pumps under small-sample conditions.
Health Assessment for Hydraulic Servo System Using Manifold Learning Based on EMD
Yujie Cheng, Chen Lu, Jian Ma
This study proposes a health assessment method for the hydraulic servo system using manifold learning based on empirical mode decomposition (EMD). An RBF neural network is adopted as a fault observer for the hydraulic servo system to generate a residual error signal. Then, the residual error signal is decomposed by EMD to form the initial feature matrix. To extract more sensitive features and reduce time consumption, isometric mapping algorithm is introduced to reduce the dimensionality of the initial feature matrix. Furthermore, the singular values of the reduced feature matrix are extracted for the subsequent health assessment. Considering the traditional Euclidean distance metric can only reflect local consistency, this study utilizes manifold distance (ManiD) to measure the health condition of the hydraulic servo system. Finally, the ManiD is converted into a confidence value, which directly represents the health status. Experiment results demonstrate the effectiveness of the proposed method.
A New Gerabox Fault Diagnosis Method Based on Lucy–Richardson Deconvolution
Xinghui Zhang, Jianshe Kang, Hongzhi Teng, Jianmin Zhao
Gear and bearing faults are the main causes of gearbox failure. Till now, incipient fault diagnosis of these two components has been a problem and needs further research. In this context, it is found that Lucy–Richardson deconvolution (LRD) proved to be an excellent tool to enhance fault diagnosis in rolling element bearings and gears. LRD’s good identification capabilities of fault frequencies are presented which outperform envelope analysis. This is very critical for early fault diagnosis. The case studies were carried out to evaluate the effectiveness of the proposed method. The results of simulated and experimental studies show that LRD is efficient in alleviating the negative effect of noise and transmission path. The results of simulation and experimental tests demonstrated outperformance of LRD compared to classical envelope analysis for fault diagnosis in rolling element bearings and gears, especially when it is applied to the processing of signals with strong background noise.
Optimization of Influential Process Parameters on the Deep Drawing of Aluminium 6061 Sheet Using Taguchi and Finite Element Method
Van Quang Nguyen, Balamurugan Ramamurthy, Jau-Wen Lin
The plastic deformation behavior of axis symmetric aluminium 6061 cups was determined by analyzing the four important deep drawing process parameters, namely blank temperature, die edge radius, blank holder force and friction coefficient. Taguchi techniques along with finite element method (FEM) were used to determine the importance of process parameters. The Taguchi method was used to analyze the influence of each process parameter. From the deformation result and analysis of variance (ANOVA), it was determined that the temperature of the blank has a major influence on the deformation characteristic of aluminium 6061 sheets followed by die edge radius, coefficient of friction, and blank holder force. The optimum levels of the four factors in determining the deformed cup heights are found to be blank temperature of 450°C, die edge radius of 14 mm, coefficient of friction of 0.60 and blank holder force of 9 KN.
Effective Numerical Analysis Method Applied to the Roll-to-Roll System Having a Winding Workpiece
Sungham Hong, Juhwan Choi, Sungsoo Rhim, Jin Hwan Coi
The design and development of Roll-to-Roll (R2R) system has been mainly executed by the expert’s experience. There are some important issues in the numerical analysis method about a roller path and the control of the R2R system. This study proposes the efficient R2R system analysis methods. The first one is an Approximated Winding Length Estimation (AWLE) algorithm which can calculate the analytic winded length of a workpiece. The winder can be approximated with line and arc segments at this algorithm. As a result, in the numerical model of the R2R system, we can replace the winder characteristics with the AWLE algorithm. The second one is the contact algorithm between workpiece and rollers. This contact algorithm must be stable and fast for precise analysis. The third one is the flexible workpiece model. The workpiece can be modeled by finite elements. By describing the implementation of these important methods, this paper proposes an efficient R2R system analysis method.
Study on the Design Adaptive Recurrent Wavelet Neural Network Control of an Auto TIG Weld System
Yung-Lung Lee, Shou-Jen Hsu, Yen-Bin Chen
An adaptive recurrent wavelet neural network control (WNN) method was developed to improve quality and system performance in welded aluminum alloy vacuum chamber production. Tests were carried out using a multi-gun automatic system. Using WNN, this research is meant to overcome weld inconsistencies and faults that cause leaks and are due to variability of skill and performance among human operators. By using this method to control welding current, wire feed rate, argon flow rate and welding speed, desired results are hopefully achieved.
On the Hybrid-Driven Linkage Mechanism with One Input Cycle Corresponding to Two Output Cycles
A hybrid-driven five-bar linkage mechanism with one input cycle corresponding to two output cycles is presented. The proposed linkage mechanism is driven by a constant-speed motor and a linear motor, respectively. The output link can generate two same required output cycles during a single input cycle, while the rotational input link rotates with a constant angular speed, and the linear input link follows a reciprocating motion along a specified linear guide fixed on the rotational input link. The configuration, displacement relationship between the input and output links, and conditions of mobility of this proposed mechanism were studied, and a kinematic analysis was performed. The selection of the instantaneous motion trajectory of the linear input link and an optimal dimensional synthesis are also described. An example is provided to verify the feasibility and effectiveness of this methodology.
A Contact Ratio and Interference-Proof Conditions for a Skew Line Gear Mechanism
Yueling Lv, Yangzhi Chen, Xiuyan Cui
Line Gear (LG) is an innovative gear which is mainly applicable to micro mechanical systems proposed by Yangzhi Chen. A Skew Line Gear Mechanism (SLGM) is one pair of LGs transmitting force and motion between two skewed axes. In this study, a design formula of a contact ratio for a SLGM is deduced, and eight influencing parameters are found. The influences of six parameters on a contact ratio for a SLGM with non-vertical skewed axes are studied by using of two coordinate parameters given definitely. The principal influencing parameters on a contact ratio for a SLGM are obtained. Moreover, two types of interferences between the driving and the driven line teeth are discussed, then these geometric parameter formulas for the interference-proof conditions are deduced, and design formulas of a maximum line tooth number for the driving line gear are derived for different interference-proof conditions.
Bearing Compound Fault Accoustic Diagnosis Based on Improved Blind Deconvolution Algorithm
Nan Pan, Xing Wu, Yu Guo
In the progress of bearing fault acoustic testing, signals picked up by acoustic sensors are usually mixed with fault source signals and other noise signals due to the complexity of mechanical signals and various interference sources. In order to solve the above problems, an improved blind deconvolution algorithm is put forward. The proposed algorithm applies adaptive generalized morphological filtering to the observed signals to retain their characteristic details, and then utilizes an OMP algorithm based on the minimum kurtosis to restore the periodical signals in the mixed signals in order to reduce the impact of the periodic components on blind separation. Finally, the improved Kullback–Leibler (KL) distance algorithm is employed to calculate the distances between independent components, which is used as the clustering index, and then to perform fuzzy C-means clustering. The experiment results of bearing compound fault extraction in real working-environment demonstrate the accuracy and reliability of the proposed algorithm.
A General CAD/CAM Model for Apt-Like Rotary Milling Cutters
Chang-Tzuho Wu, Nien-Te Liu
This paper presents a general mathematical model for NC-machining an APT-LIKE rotating cutter. The design model of cutting-edge and helical groove is also developed by using the principles of differential geometry and kinematics. Based on the envelope condition, approaches for solving the inverse problems that are related to the manufacturing models are also presented. The velocities of the cutter in the radial and axial directions are then determined based on the gouging avoidance of grooves. The results of the numerical experiment indicate that the proposed systematic design method by using 2-axis NC machine setup is feasible and reliable.
Integration Fault Detection and Tolerant Control in Micro-Satellite Attitude Propulsion Mode Application
The paper refers to a tolerant control method which is reconfigurable to micro-satellites when they are out of order. The integrated approach to the design of thruster control reconfigurable fault-tolerant control system is proposed. The scheme includes a control effectiveness factor and a reconfigurable fault-tolerant controller. The fault detection, diagnosis and controller reconfiguration are carried out using the control effectiveness factor based on the information from a two-stage Kalman filter. By using the two-stage Kalman filter and digital controller, the nonlinear plant will be discretized. We present sufficient conditions under which a discrete-time controller that input-to-state stabilizes an approximate discrete-time model of a nonlinear plant with disturbances. The result shows the method enables us to solve the system faults and meet the requirement when there is a fault in the micro-satellites attitude control system.
Real-Time Reliability Assessment and Lifetime Prediction for Bearings Using the Individual State Deviation Based on the Manifold Distance
Zu-wang Gan, Jian Ma, Chen Lu, Hongmei Liu, Tian-min Shan
In recent years, the real-time reliability evaluation and life prediction for rolling bearings has attracted more attention. Most of the existing methods employ real-time transformation of traditional reliability indices, performance degradation trajectory or distribution analysis, which usually have certain limitations in terms of accuracy and applicability. This paper proposes a method for bearing real-time reliability evaluation and life prediction to avoid the negligence of real-time transformation of the monitored individual, as well as reduce the errors caused by the randomness from individual bearing operational process. The individual state deviation of a running rolling bearing geometrically measured by manifold distance is normalized into a state deviation degree, which is used to formulate a modified real-time reliability model for realtime reliability evaluation and lifetime prediction. Finally, the feasibility and efficiency of this method is validated by bearing run-to-failure experiments.
On-Line Performance Assessment and Fault Diagnosis of Mechanical Systems
Shang-Liang Chen, Yin-Ting Cheng, Hsien-Cheng Liu, Yun-Yao Chen
This study integrates sensors, signal capture equipment, industrial computers and machinery health checkup software to develop an On-line Performance Assessment and Fault Diagnosis of Mechanical System, helping engineers predict mechanical conditions. Physical quantities captured by the sensors is utilized to process physical signals, and the Wavelet Packet Energy method is used for the feature extraction of non-stationary signals in coordination with the Principal Component Analysis for feature selection. This study establishes On-line Performance Assessment and Fault Diagnosis of Mechanical System based on Discriminant Analysis which is able to immediately determine the mechanical performance. When abnormal mechanical conditions occur, Bayesian Network will be activated to construct error diagnostic model and determine possible causes of error or malfunction of the machinery. Finally, the system is applied to the fan motor, high-speed spindle motor and AC motor of the machine tool. Experimental results show that the theory can effectively diagnose mechanical performance remarkable with an accuracy rate of 92.50% or higher.
A Study on the Thermal Characteristics of the Grinding Machine Applied Hydrostatic Bearing
Bo-Sung Kim, Gyeong-Tae Bae, Gwi-Nam Kim, Hong-Man Moon, Jung-Pil Noh, Sun-Chul Hu
In order to activate the high precision and multi-functional machine tool, adequate technical level of the high-precision products is required. The hydrostatic bearings is used as a method for producing the highprecision products. The hydrostatic bearing has a relatively small run-out compared to its shape error by fluid film effect in hydrostatic state similar to pneumatic bearing and has high stiffness, load capacity and damping characteristics. In this study, we conducted a study on the thermal deformation of the grinding machine that has a great influence on the machining accuracy of the product. The temperature of the front bearing is 10°C or higher than the temperature of the rear bearing. Thermal deformation of the spindle was found to be dependent on the temperature of the hydrostatic bearing and could identify the overall thermal characteristics of the grinding machine.
Defect Improvement of Extrusion Dies Using Combination of FEM Stress Analysis with the Taguchi Method
Kao-Hua Chang, Ching-Wei Shih, Gow-Yi Tzou
This study aims at analyzing the influence of the maximum principal stress on Tungsten Carbide Steel die core in an extrusion die which caused the crack of die core, and then adjusts the dies assembly method in order to improve the service life of die. In this study, we combine FEM simulation software with the Taguchi Method L9(34) to choose the cobalt content for die core materials, and the quantity of shrink fit while assembling the die core and die case as the reference parameters. When carrying out the simulation process, we compared the changes of the maximum principal stress of the die core caused by the plastic deformation of die materials to achieve the minimum expected value as the goal for the most optimal die combination. Then, the results obtained are to make dies in trial and mass-production practically; as a result, the die life is improved from the original 1000 to 150,000 pcs, which is more than 150 times better than before.
The Study of an Innovative Heat Removal Model of the Aluminum-Acetone Flat Plate Heat Pipe on High Power LEDs
Po-Jen Cheng, David T.W. Lin, Wu-Man Liu, Jui-Ching Hsieh, Chi-Chang Wang
It is well known that heat generation will be harmful to high power LEDs. It is hardly effectively dissipated and results in a serious problem in the luminous efficiency. The most important issue in LED research is to find a potential design of heat removal. The purpose of this study is to design the LEDs combined with the cooling module of the aluminum-acetone flat plate heat pipe by the experimental and numerical simulation for obtaining high efficiency in heat removal. The high power LEDs with and without heat pipe cooling module are compared. The numerical simulation is built and agrees with the experiment. The heat removal efficiency of the cooling module reaches 92.09% and drops the junction temperature of LED about 36°C. This cooling module has proven to be effective in solving the heat concentration problems associated with the LED chips. In short, the phase change cooling module will apply on the electronic component of high heat concentration for more effective cooling method.
Full journal title: Transactions of the Canadian Society for Mechanical Engineering
Abreviated journal title: Trans. Can. Soc. Mech. Eng.
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