Transactions of the Canadian Society for Mechanical Engineering
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Volume 40 (2016), Issue 5
Document delivery robot based on image processing and fuzzy control
Jih-Gau Juang, Chang-Yen Yang
The objective of this study is to integrate image processing, pattern recognition, RFID, and fuzzy theory into an omnidirectional wheeled mobile robot for receiving and delivering documents between rooms. In image pre-processing, the Hue-Saturation-Lightness color space is applied to avoid light interference, and then grayscale image threshold is used to obtain binary image. The median filter is utilized to filter the noises of speckle and salt-and-pepper, so color segmentation is then applied to capture desired color for tracking control. Pattern recognition is performed by the Adaptive Resonance Theory. RFID reader and room tag is used to verify the room number of the destination so that the recognition error from image processing can be avoided. Fuzzy theory is implemented into an omnidirectional wheeled mobile robot control design for driving the wheels of the robot. Experimental results show that the proposed control scheme can make the omnidirectional mobile robot move to destination, receive and deliver documents between offices.
Development of an automatic measurement and matching machine for columned battery cells
Xiaoxing Li, Yi-Hua Fan, Ching-En Chen, Chia-Hui Tsao, Yu-Ming Chen, Sheng-Chung Hsieh
An automatic measurement and matching machine for columned batteries is developed in this study. The automatic machine consists of a battery feeding case, an intermittent separation feeding mechanism, a test region, eight classification transport channels, and battery depositary boxes. Besides the mechanism design, a human-machine interface and control program are written in VB language. The program provides the control and monitoring program for the auto-measurement system. The program cannot only read the measurement data and control the automatic machine, but also store these data and provide the test data histories for each cell supplier to the user. The experimental results show that the automatic machine could examine and classify the columned battery cells efficiently and decrease the demand of manpower. The results also show that the total measured and sorting quantity of one machine for eight hours is about 5760 pieces, which is greater than the 3500 pieces measured by one manpower.
Numerous simulation on the existence of fluctuation of instantaneous availability
Yang Yi, Ren Si Chao, Fan Guimei, Kang Rui
This paper considers the fluctuation of the instantaneous availability by numerical methods for a one-unit repairable system. The choices of the failure rate and repair rate are linear or cubic increasing functions. For the equation of instantaneous availability composing of two convolutions, the following numerical methods are used: the composite Simpson formula and the trapezoidal formula. That is to say, the simulated curves of instantaneous availability under any condition are obtained. Through the simulated results, when the failure rate and repair rate are selected as increasing functions, the extremum of simulated curve exists so fluctuation exists. On the other hand, if parameters of increasing functions become smaller, the fluctuation weakens.
Design of a fuzzy-PID controller for a nanoscale X-Y platform
Xiuli Zheng, Yi-Hua Fan, Ching-En Chen, Ya-Qi Lin, Hung-Wen Liao, Sheng-Chung Hsieh
A fuzzy-PID controller design was proposed in this paper for a nanoscale platform positioning system. The target nanoscale X-Y platform is mounted on a pantograph mechanism and restricts the rotation by two small sliders; the device is driven by a traditional X-Y platform with common precision. The goal of this study is to drive the target platform’s movement in the region of 5 mm × 5 mm for the positioning, with repeated positioning accuracy error less than 200 nm by the traditional X-Y platform. Due to the different PID parameters affecting platform positioning accuracy and system response for the two axes, the fuzzy-PID controller will train to fit the mechanism to promote the positioning precision and path control effect. The simulation and experimental results indicated that the proposed method is feasible for nano-scale micro-platform positioning.
Contact stress and radial stiffness of a cylindrical roller bearing with corrected roller generator
Guanci Chen, Hailiang Wang
A method has been developed to study the radial stiffness of a cylindrical roller bearing with corrected roller generator. First, the finite-length contact question of roller-race contact was solved by cutting contact surface into slices and considering the influences among slices by a flexibility coefficient matrix, which was more accurate than the traditional method. Further, the more precise load-approach function of the contact of race and roller with corrected generator was determined. Then, the radial stiffness of a cylindrical roller bearing has been derived by coupling this load-approach function into a complete bearing mechanical model. Results show that the corrected roller generator has a great influence on the bearing radial stiffness. The maximum stiffness difference among the cases of straight and crowned generators is 28.7%. The bearing radial stiffness decreases rapidly with the rise of profile maximum deviation hmax. It is worthy noting that there is a sudden change of stiffness with the adding of load when the bearing is with clearance.
Pulsed electrochemical micro machining of invar (Fe-Ni) film using an electrode array
Kwang-Ho Chun, Seung-Geon Choi, Eun-Sang Lee
Recently, invar (Fe-Ni) material has been applied to OLED shadow masks due to its thermal change characteristics and thermal expansion coefficient. The most widely used manufacturing methods for invar are etching and laser machining, but they have problems like non-machined areas generated by etching and surface burning in laser machining. For this reason, an alternative machining method is necessary. In this study, pulsed electrochemical machining (PECM) has been applied to fabricate an OLED shadow mask. PECM is a highly promising technology for shadow mask manufacturing because it can produce micro-scale and complex tapered holes in one process. A pilot experiment was carried out to find a suitable electrolyte for invar film, and an array of coated Ti electrodes was used to fabricate micro holes.
Performance investigation of an SI engine with variable valve timing and lift based on magneto-rheological valve
Yaojung Shiao, Wen-Hsin Cheng
Cylinder valve with variable timing and variable lift is a potential technology to improve engine performance. This research studied cylinder dynamics of a spark-ignition (SI) engine equipped with a new full variable valve system (VVS) based on an innovated magneto-rheological (MR) technology. An MR valve block was combined with a conventional inlet valve in this MR VVS. The study obtained many patterns of valve opening/closing by controlling current to the MR VVS, which controlled the MR fluid flowing through magnetic plate block. Magnetic simulations were performed for the new MR VVS to investigate the relationships among MR valve displacement, valve lift, and valve timing. Simulation results showed that the MR VVS provided high degrees of freedom of valve timing and lift for gasoline engine to produce different torque modes and high engine efficiency. The abilities of this MR VVS to become essential technique of high-efficiency engine were confirmed in the results.
An investigation of forging streamline and tool design on multi-stage cold forming of a long circular pipe part
Ching-Wei Shih, Gow-Yi Tzou, Kao-Hua Chang
The study aims to explore the reasons for why the fracture defects in the forging of a long circular pipe part occurred. Besides, the tool design has been proposed to eliminate the fracture defects. The flow direction, the velocity, the effective stress, the effective strain, the damage value, and so on, can be observed by using the point tracking function in the commercial simulation software. Moreover, the forging stream line occurring in the work-piece formation based on the simulation software is compared with that in the real product in order to understand the reasons for the fracture. The tool designs are modified accordingly, and the simulation software is used to confirm the acceptance of tool designs. Finally, appropriate forging has been performed to as per product requirements.
Design and evaluation of a ride comfort based suspension system using an optimal stiffness-determination method
Jing Zhao, Pak Kin Wong, Zhengchao Xie, Caiyang Wei, Rongchen Zhao
This paper focuses on a ride comfort based suspension (RCS) system using an optimal stiffnessdetermination method. The proposed RCS system is composed of a variable hydraulic damper with gas chamber (VHDGC) and an air spring. In this work, the detailed structure, modeling process and parameter sensitivity of the proposed VHDGC are presented. Moreover,the mathematical relationship between the proposed damper and the air spring is considered. Numerical results reveal that the ride comfort of the proposed RCS system can be greatly improved as compared with the passive suspension. In addition, the overall performance of the RCS system is also guaranteed. In sum, the proposed RCS system is a promising solution in improving the ride comfort of the vehicle.
Investigation of characteristics of shear layer: Application of synthetic jet in backward-facing step flow field
Chia-Wei Hsu, San-Yih Lin
The purpose of this research is to explore the two-dimensional backward-facing-step flow perturbed by a synthetic-jet actuator experimentally. The step was placed in a low-speed wind tunnel and the flow passage expansion ratio was 1.07. The Reynolds number was Reh = 1.18×104 based on the step height and the upstream velocity before the step edge. An electromagnetic loudspeaker was used to generate synthetic jet flows in the direction of the main flow through a slot of 1 mm in width. The peak value of the driven AC voltage was 8 V and the frequency varied in the range of 80-120 Hz. The velocity of the flow field was measured by hot wire anemometers. The distributions of averaged velocity, fluctuation intensity, and Reynolds stress were analyzed to understand the influences of the synthetic jet. The characteristic frequencies were also obtained. The size of the recirculation region was affected by the synthetic jet. The downstream reattached flow was more stable with the synthetic-jet perturbation.
Full scale experiment and numerical analysis for the performance of heat exchanger in molten carbonate fuel cells
Seon-Hwa Kim, Byeong-Keun Choi, Young-Su An
This study presents a numerical simulation of heat transfer and flow characteristics of the heat exchanger in molten carbonate fuel cell system. In this study, the actual size of the heat exchanger was simulated in order to avoid errors that can occur from the scale-down test, also the simulation gas (air) was verified with the heat duty of 800,000 kcal/hr. It is analyzed by using a commercial heat exchanger calculation code based upon the test condition. It is found that a reasonable agreement is obtained from comparison between the predicted results and the measured data. Furthermore, the verified similarity was presented in this analysis. In particular, the simulation gas used for the shell side service for the heat exchanger is obtained through the combustion calculation, i.e. by using a flow rate of the fuel gas. In addition, the performance of the heat exchanger is predicted under various conditions in the fuel cell operation conditions by the numerical model.
Numerical analysis of the effects of streamlining geometry and a vector wall on the thermal and fluid flow in a sru thermal reactor
To resolve the abnormality of a SRU thermal reactor under high temperature operation and to improve the recovery of sulfur, the effects of streamlining geometry and a vector wall on the thermal and fluid flow in a SRU thermal reactor are investigated numerically. It is found that the compression effect caused by a streamlined zone 1 corner leads to an increase in the average temperature. However, the corner recirculation zone using a streamlined zone 1 corner becomes smaller and this yields a reduction in temperature. The combined effect of compression and a smaller corner recirculation zone leads to an optimal radius of curvature at the zone 1 corner. The lowest peak temperature is obtained using a radius of curvature 1m at the zone 1 corner. With larger radii of curvature at the zone 1 corner, the compression effect overwhelms the effect of a smaller corner recirculation zone and the peak temperature is higher. The specific arrangement of the vector wall holes results in a spiral motion behind the vector wall. The average temperature increases and becomes more uniform across a vector wall. The peak temperature and the exit sulfur concentration are higher using a vector wall. Finally, the skin friction coefficient increases abruptly across a vector wall but becomes lower downstream, compared with using a choke ring. The results of this paper are helpful in improving the performance and safety of a SRU thermal reactor.
Effects of surface forces on squeeze ehl motion between elastic ball and elastic coated surface
Li-Ming Chu, Jaw-Ren Lin, Hsiang-Chen Hsu, Yuh-Ping Chang
The effects of surface forces (SF) and coated layers (CL) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts are explored under constant load condition by using the finite difference method (FDM) and the Gauss–Seidel iteration method. The transient pressure profiles, surface force, film shapes, and elastic deformation during the pure squeeze process under various operating conditions in the TFEHL regime are discussed. The simulation results reveal that the difference between SFEHL model and EHL model is apparent as the film thickness is thinner than 5 nm. The oscillation phenomena in pressure and film thickness come mainly from the action of solvation forces. At contact region, the greater elastic modulus and smaller coating thicknesses, the greater pressure distribution, and the smaller film thickness. The film thicknesses are found reverse at outside the contact zone. At the exit region, i.e. the minimum film thickness region, it is valid that the greater the elastic modulus and the smaller the coating thicknesses, the greater the solvation pressure distribution. The effects of surface forces become significant as the film thickness becomes thinner.
Calculation of oil tank volume and report generation system with trim and list corrections
Ming-Sen Hu, Chia-Rei Tao
The capacity of ship’s oil tanks is usually designed as a tabled form in order to obtain oil volumes by using the measured ullage heights. However, the tank walls easily deform or distort due to long-term heavy loading. This phenomenon may cause serious errors that the carrying capacity in oil tanker does not match with the values of the tabled form. In this paper, we perform an oil tank volume calibration project that aims to develop a tank volume calculation and report a generation software with trim and list corrections. The current internal specification for each tank is measured first, and then all specification data measured can be input to this software system to calculate each tank’s volume. These calculated results will be verified by actual delivery volume tests. This software system has been applied to the Der-Yun Oil Tanker of CPC Corp. The result shows that the overall error of calibrated volume for all tanks is under 0.1%. It is proved that this system highly improves the correctness of the vessel’s carrying capacity.
Structural identification of dynamic systems using parameter updating reanalysis method: experimental investigation using the measured data
Kyoungbong Han, Dooyong Cho, Sun Kyu Park
In this study, the proposed parameter updating reanalysis method was directly used on the measured data of the structures. Structural reanalysis generates a correlated analytical model that defines the structure on applying the initially assumed baseline analytical model and is presented through the structure’s FRF (frequency response function). Two numerical tests were previously conducted in order to demonstrate the effectiveness of the suggested reanalysis method. The suggested method generates the correlated analytical model with higher precision, as compared to the existing method, despite the application of the noise factor to the observed data. The method initially proven by the numerical experiment of an actual structure was applied to a pseudo-dynamic test on the full-scale concrete pier. The results indicate that the proposed reanalysis is useful even for application to response data of the actual structure.
Establishment of dynamic equations for damped systems based on quasi-variational principles
Yuhua Pan, Yuanfeng Wang, Li Su
In this paper, quasi-variational principles for non-conservative damped systems are studied. A Hamiltontype quasi-variational principle for non-conservative systems in analytical mechanics and a quasi-variational principle of potential energy in non-conservative elastodynamics systems are proposed in simplified forms respectively, by using the direct variational integral method. On the basis of the standard linear solid model for viscoelastic materials, the dynamic equations of exponentially damped systems are established through the proposed quasi-variational principles. A distinction between the internal damping described by exponential damping and the external damping described by viscous one in a vibrating structure is according to different physical mechanisms, which gives some indication of the correct mechanism of damping.
Research on the self-synchronous vibration of fatique loading tests for wind turbine blades
Huang Xuemei, Zhang Lei’an, Tao Liming, Wei Xiuting
To carry on fatigue loading tests for wind turbine blades accurately, the self-synchronous vibration mechanism of loading system was investigated. Firstly, the mathematical model of vibration was deduced based on LaGrange Equation, thus the influence factors of self-synchronous vibration could be obtained. Then to study the influencing rules of the initial phase difference between loading equipment and blade, a simulating model was constructed to carry on the numerical simulation and it was found that when the driving frequency of the loading equipment was the same as the natural frequency of the blade, a different initial phase separation would generate different effect on self-synchronous vibration. Finally, an on-site fatigue test system was established to verify the accuracy of mathematical and simulation model mentioned above. It could be concluded that the test results were consistent with the simulating result. The research on the self-synchronous vibration performance of loading system for blade could supply a theory support for the sequent control of blade’s fatigue tests precisely.
Optimal prediction and design of surface roughness for CNC turning of AL7075-T6 by using the Taguchi hybrid QPSO algorithm
Wen-Jong Chen, Chuan-Kuei Huang, Qi-Zheng Yang, Yin-Liang Yang
This paper combines the Taguchi-based response surface methodology (RSM) with a multi-objective hybrid quantum-behaved particle swarm optimization (MOHQPSO) to predict the optimal surface roughness of Al7075-T6 workpiece through a CNC turning machining. First, the Taguchi orthogonal array L27 (36) was applied to determine the crucial cutting parameters: feed rate, tool relief angle, and cutting depth. Subsequently, the RSM was used to construct the predictive models of surface roughness (Ra, Rmax, and Rz). Finally, the MOHQPSO with mutation was used to determine the optimal roughness and cutting conditions. The results show that, compared with the non-optimization, Taguchi and classical multi-objective particle swarm optimization methods (MOPSO), the roughness Ra using MOHQPSO along the Pareto optimal solution are improved by 68.24, 59.31 and 33.80%, respectively. This reveals that the predictive models established can improve the machining quality in CNC turning of Al7075-T6.
Sub-optimal algorithm second-order sliding mode control for a synchronous reluctance motor speed drive
Huann-Keng Chiang, Wen-Bin Lin
A sub-optimal algorithm second-order sliding mode controller (SOSMC) was presented for a synchronous reluctance motor (SynRM) speed drive. SOSMC is an effective tool for the control of uncertain nonlinear systems since it overcomes the main chattering drawback of conventional sliding mode control. The practical implementation of SOSMC has simple control laws and assures an improvement in sliding accuracy with respect to conventional sliding mode control. This paper proposes a control scheme based on sub-optimal algorithm SOSMC. The proposed SOSMC is robust against motor parameter variations and mitigates chattering phenomenon. Experiments were conducted to validate the proposed method.
The development of a tilt-rotor unmanned aerial vehicle
Jie-Tong Zou, Pan Zheng-Yan
In this research, we had developed quad-rotor unmanned aerial vehicles with the tilt-rotor mechanism. People are eager to fly therefore the development of aerial vehicles, such as fixed-wing aerial vehicles and multi-rotor aerial vehicles, has grown rapidly in recent years. The multi-rotor vertical take-off and landing (VTOL) unmanned aerial vehicle which can fly stably and hover in a fix position developed the fastest. Comparing the general fixed-wing aircrafts and rotorcrafts, fixed-wing aircrafts can fly with a higher speed than rotorcrafts, but they do not have the VTOL and hovering abilities. The proposed quad-rotor aerial vehicle with tilt-rotor mechanism has two flight modes: rotorcraft and fixed-wing aircraft flight mode. It can take-off and land vertically in rotorcraft mode and can also fly faster in fixed-wing aircraft flight mode. The dynamic equations of the proposed quad-rotor aerial vehicle with tiltrotor mechanism are also studied in this paper.
Glass cutting with elongation optics in comparison to conventional methods by laser
Shih-Jeh Wu, Hsiang-Chen Hsu, Wen-Fei Lin
In this study, the authors applied a pico-second 532 nm laser with state of art elongated optics on cutting soda lime glasses and compared the results with three other methods by conventional focusing technique namely; dice-and break, direct wobbling cut (both by UV laser), and stealth cut (by pico-second IR laser). The dice-and-break method has the fastest speed, however, the roughness is poor. The wobbling method is poor in both roughness and cutting speed. The dual-focused beam has the smoothest cross-section with fast speed in one step. Of the four methods, the elongation optics has the best overall performance. The improved quality attributes to a well-managed energy distribution.
Investigation of the electrode design of a single-mode piezo-electric actuator
Shyang-Jye Chang, Zheng-Yang Hsieh
This study investigated the electrode design and output performance of a single-mode piezoelectric actuator. The relevance between the design parameters of the electrode and the vibration amplitude of the friction element was determined. Two split electrode design methods, horizontal and vertical, were investigated. The Taguchi method was used to investigate the relevance of the exciter electrodes and the vibration amplitude of the piezoelectric actuator. The simulation experiments demonstrated that the vertical split electrode design can be used to adjust the Y vibration amplitude. The thrust force measurement demonstrated that the thrust force of the piezoelectric actuator can be adjusted by using the split electrode design.
The influence of factors ona heat transfer performance of a loop thermosyphon system
Li-Chieh Hsu, Guo-Wei Wong, Kung-Ting Chen
The influence factors on the heat transfer performance of a loop thermosyphon system, a passive cooling device, are studied systematically. The parameters investigated include types of enhanced boiling structure, the depth to width ratio of enhanced boiling structures, the gap of evaporator, the condenser height and the inclination of evaporator. The results show the depth to width ratio and the condenser height has positive influences on the heat transfer performance. An optimal channel gap of evaporator exists and possesses better heat transfer performance. The inclination effect of evaporator may not be favorable to heat transfer. Among those, the horizontal and 90° inclination of evaporator has better cooling performance.
Design of the transmission mechanism used in a multipoint mortise lock
Hsing-Hui Huang, Yi-Ming Lin
A multipoint lock is a useful lock which can provide more security and is convenient for the user. One of the aims of this article is to study how a multipoint lock is designed systematically by utilizing a mortise lock. Based on a systematic design methodology, the concepts and the atlas of designs are synthesized systematically. A feasible mechanism is further chosen for detailed design. The computer simulation is developed and the basic stress analysis is also constructed for verifying the design results. Finally, the prototype is also built. The results of this study provide a valuable reference for the design and analysis of a mortise lock’s mechanism.
The synthesis of the planar linkages with symmetrical configurations
Chia-Chun Chu, Deng-Maw Lu
The mechanisms that employ symmetrical configurations can be found in the steering mechanisms, double open refrigerator, roof boxes, and double open windows, among others. They are useful for some special applications with kinematic symmetry. There have been studies about the linkage synthesis, especially in the research of planar closed chains, from as early as 1960s. However, no study has focused on the symmetry of planar linkages. Thus, the purpose of this paper is to present a methodology to synthesize the configurations of planar linkages. The systematic methodology can be divided into structure synthesis, configuration synthesis and results produced from three major processes. Finally, four suitable results of up to six-bar linkages can be obtained, for example. The four results include one four-bar linkage and three six-bar linkages.
The Engineering design and transmission efficiency verification of helical spur gear transmission with single gear pair
Long-Chang Hsieh, Tzu-Hsia Chen
The transmission efficiency of a gear reducer (ηT) can be expressed as ηT = ηm×ηb×ηs, where ηm is the meshing efficiency of gear pairs, ηb is the efficiency of bearings, and ηs is efficiency of oil seals. Based on the research of Hsieh, et al., the meshing efficiencies of a helical spur gear pair (4, 77) are between 96.13 and 99.20%. The purpose of this article is to analyze the theoretical transmission efficiencies of non-standard helical spur gear pair and verify the theorem. According to the gear data, the theoretical transmission efficiencies are calculated to be 90.13–97.85%. And its test values of transmission efficiencies are between 82.3 and 91.9% (acceptable values). There are only 5.39–14.14% errors between these two values. This manuscript verifies that a helical spur gear pair can have a high reduction ratio (20–30) and acceptable real transmission efficiencies.
Maintainability analysis and evaluation of flexible cables based on delmia
Meixia Tu, Lv Chuan, Meihui Wang, Dong Zhou, Yiliu Xu, Bile Wan, Wenxing He
This paper presents a virtual maintenance application for the maintainability analysis and evaluation of flexible cables to provide recommendations on the maintainability of products containing cables during the early stages of product design. This paper provides a methodology for complex products containing cables detecting the potential defects via virtual maintenance technology. An integrated platform for analyzing and evaluating cable maintenance in a virtual environment is designed. Then, based on the maintenance simulation platform DELMIA, a cable maintainability evaluation system is proposed. The system consists of an evaluation element, a evaluation criteria, and an evaluation method. A case study on aviation aircraft subsystem disassembly was used to validate the feasibility of virtual maintenance in improving cable maintainability designs.
Dynamic modeling and analysis of multi-stage planetary gears coupled with central bearings and housing
Zheng-Ming Xiao, Xing Wu, Qing Chen
This paper proposes a coupling dynamic model for multi-stage planetary gears train (PGT) based on thegearing theory and Lagrange equation, which is developed by analyzing the displacement relationships of gearing system and the influence of floating components. The time-varying mesh stiffness, bearings in housing, and the torsional support stiffness of ring gears are also considered. This model has 26 degrees-of-freedom (DOF) and adopts three planar DOFs for each central component, mesh phasing relations among planetary gears, and the rotational DOF for the planets of each stage. The modified transverse-torsional model is established in the rotating Cartesian coordinates by using the lumped-parameter method; thus this model is more accurate than the purely torsional model for describing the physical dynamics. The acceleration data is tested by using the scheme of a back-to-back power circulation set-up, and the vibration properties are also studied.
Bearing performance degradation assessment by orthogonal local preserving projection and continuous hidden Markov model
Tao Liu, Xing Wu, Yu Guo, Chang Liu
Bearing is the key component in rotating machine. It is important to assess the performance degradation degree of bearings for making proactive maintenance and realizing near-zero downtime. A methodology based on orthogonal local preserving projection (OLPP) and continuous hidden Markov model (CHMM) is introduced in bearing performance degradation assessment. Firstly, the time domain, frequency domain and time-frequency domain features are extracted from the vibration signals. Then, the multi-dimensional features are reduced by OLPP. And the selection of the adjacent paragraph parameters in OLPP is optimized adaptively by minimizing the ratio of between-class distance to within-class distance. A CHMM is trained by using the reduced feature in normal condition. At last, the test bearing data are input into the pre-trained CHMM to calculate the log-likelihood of the test data, which can assess the performance degradation of bearings quantitatively. A bearing accelerated life experiment is performed to validate the feasibility and validity of the proposed method.
Study on micro contact characteristics of joint surface based on a fractal theory
Lihua Wang, Pengcheng Wang, Zu Yang, Yusong He
In order to understand the microscopic mechanism of the joint surface, simulations of three-dimensional microscopic topography of the joint surface are done based on the fractal theory. Further, the three-dimensional microscopic surface contact models of the joint surface are designed using the fractal simulation surface topography. Then, the contact simulation analyses are carried out using finite element method and the microscopic elasticity and elastic-plastic contact characteristics between the three-dimensional microscopic surfaces are studied. The research results showed that the displacement along normal direction, contact area, and contact pressure of the joint surface increase nonlinearly with an increase in the contact load and vary with the roughness of the joint surfaces. This study provides a theoretical basis for the further research on the microscopic mechanism of the joint surface.
Research on condition monitoring of speed reducer of industrial robot with acoustic emission
Xiaoqin Liu, Xing Wu, Chang Liu, Tao Liu
Articulated industrial robots are widely used for factory automation, e.g., the car manufacture industry. As other machines, the transmission system of industrial robot is prone to fail after long term operation. Speed reducer is the key component of the transmission system, and it is important to detect its incipient faults to avoid breaking down. However, until now, few techniques have been proposed to diagnose the reducer without disassembly. Our research on monitoring and diagnosing the speed reducer of industrial robot is reported in this paper. The technique combines inspection method of acoustic emission and signal processing of vibration signal. The characteristics of acoustic emission signal and their connections with mechanical parts of robot reducer have been studied. A defect in the rolling bearing was detected on a welding robot by this technique and confirmed in disassembly.
Full journal title: Transactions of the Canadian Society for Mechanical Engineering
Abreviated journal title: Trans. Can. Soc. Mech. Eng.
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