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Independent continuous and mapping method of
structural topology optimization based on the global stress approach
Yunkang SUI, Jili FENG, Hongling YE, Xirong PENG,
Front. Mech. Eng.. 2010, 5 (2): 130-142.
https://doi.org/10.1007/s11465-010-0011-3
There are three difficulties in topology optimization of continuum structures. 1) The topology under multiple load case is more difficult to be optimized than under single load case, because the former becomes a multiple objective based on compliance objective functions. 2) With local constraints, such as an elemental stress limit, the topology is more difficult to be solved than with global constraints, such as the displacement or frequency limits, because the sensitivity analysis of the former has very expensive computation. 3) With the phenomenon of load illness, which is similar with stiffness illness in the structural analysis, it is not easy to get the reasonable final topological structure, because it is difficult to consider different influences between the loads with small forces and big forces, and some topology paths of transferring small forces may disappear during the iteration process. To overcome difficulties above, four measures are adopted. 1) Topology optimization model is established by independent continuous mapping (ICM) method. 2) Based on the von Mises strength theory, all elements’ stress constraints are transformed into a structural energy constraint. 3) The phenomenon of load illness is divided to classify into three cases. 4) A strategy based on strain energy is proposed to adopt ICM method with stress globalization, and the problems of the above mentioned three cases of load illness are solved in terms of different complementary approaches. Several numerical examples show that the topology path of transferring forces can be obtained more easily by substituting global strain energy constraints for local stresses constraints, and the problem of load illness can be solved well by the weighting method that takes the structural energy as a weighting coefficient.
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Statistical process control with intelligence
using fuzzy ART neural networks
Min WANG, Tao ZAN, Renyuan FEI,
Front. Mech. Eng.. 2010, 5 (2): 149-156.
https://doi.org/10.1007/s11465-010-0008-y
With the automation development of manufacturing processes, artificial intelligence technology has been gradually employed to increase the automation and intelligence degree in quality control using statistical process control (SPC) method. In this paper, an SPC method based on a fuzzy adaptive resonance theory (ART) neural network is presented. The fuzzy ART neural network is applied to recognize the special disturbance of the manufacturing processes based on the classification on the histograms, which shows that the fuzzy ART neural network can adaptively learn the features of the histograms of the quality parameters in manufacturing processes. As a result, the special disturbance can be automatically detected when a feature of the special disturbance starts to appear in the histograms. At the same time, combined with spectrum analysis of the autoregressive model of quality parameters, the fuzzy ART neural network can also be utilized to adaptively detect the abnormal patterns in the control chart.
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Signal separation technology for diphase opposition
giant magnetostrictive self-sensing actuator
Xinhua WANG, Shuwen SUN, Jian ZHEN, Qianyi YA, Deguo WANG,
Front. Mech. Eng.. 2010, 5 (2): 176-183.
https://doi.org/10.1007/s11465-010-0001-5
The structure and principle of a new type of a diphase opposition giant magnetostrictive self-sensing actuator is introduced. A bridge analysis model based on variable inductance is established. Dynamic balance separation technology for the giant magnetostrictive self-sensing actuator comes true by the least means square (LMS) self-adapting algorithm. The scheme design of one important part of the circuit with the real-time separation circuit of the dynamic balance signal based on a digital signal processor is obtained. The part of the signal separated circuit is designed, which includes logarithmic-antilog practical multiplication circuit, amplifying circuit, filter circuits, and amplifier circuit. Based on the embedded system simulation software—PROTUES, the simulation effect of the circuit that separates the sensing signal from the mixed signals is obvious, which indicates that the circuit can rapidly and stably work. Moreover, the structure is simple, reliable, and meets the practical requirement.
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Structure and performance of welding joint of
Q235 steel welded by SHS welding
Junzhi HU, Sumei WANG, Xiaoli ZHAO, Shilin ZHU, Botao YU,
Front. Mech. Eng.. 2010, 5 (2): 189-193.
https://doi.org/10.1007/s11465-010-0003-3
A self-propagating high-temperature synthesis (SHS) welding-pen that can weld steel workpiece from 6 to 10 mm is developed and welds the Q235 steel. The structure and properties of the welding joint are studied. The result indicates that this type of welding is melting and the fusion zone is clear. The tensile-strength of the welding joint is 283 MPa, flexural strength is 628 MPa, impact toughness is 46.43 J·cm−2, and the microhardness of the welding joint and fusion zone are 230 HV0.1 and 255.6€HV0.1, respectively. The mircohardness of the fusion zone and the welding line are higher than that of the matrix.
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Impact force detection using an energy flow estimator
with piezoelectric sensors
Xingjun WANG, Daniel GUYOMAR, Kaori YUSE, Mickaël LALLART, Lionel PETIT,
Front. Mech. Eng.. 2010, 5 (2): 194-203.
https://doi.org/10.1007/s11465-010-0004-2
Currently, there are numerous methods for estimating impact locations. One is to find more detailed information because the system becomes complicated. Another method is to reduce energy, for which various autonomic energy harvesting methods have been developed. However, the occupied energy is still small. This paper proposes a simple, rapid, and low-powered impact estimation method based on energy flow direction estimation through a pair of piezoelectric sensors. The estimation energy flow is expressed by a Poynting vector subsequently linked to piezoelectric sensor voltage outputs. The presented approach is verified by numerical simulations and experiments.
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IPMC gripper static analysis based on finite
element analysis
Hanmin PENG, Yao HUI, Qingjun DING, Huafeng LI, Chunsheng ZHAO,
Front. Mech. Eng.. 2010, 5 (2): 204-211.
https://doi.org/10.1007/s11465-010-0005-1
Recently, a type of flexible grippers with low power supply (0–5 V) has been designed and developed for grasping small but precision parts. In previous work, the authors manufactured a soft gripper whose actuating components are made of ionic polymer-metal composite (IPMC) materials; however, there is not a comprehensive model to analyze the complete mechanics for this IPMC gripper. Therefore, this paper provides a finite element method for analyzing its static mechanics characteristics in the state with maximal stress and strain (i.e., the gripper opening largest, including the IPMC deformation, stress, and strain). Further, these electromechanical coupling relationships can be simulated by using the piezoelectric analysis module based on ANSYS software. The simulation results show that the maximal tip displacement of IPMC strips can nearly reach their own free length, the maximal stress is 54 MPa in the center of copper electrodes, and the maximal strain is 0.0286 on the IPMC strip. The results provide detailed numerical solutions and appropriate finite element analysis methodologies beneficial for further research on the optimization design, forecast analysis, and control field.
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Novel piezoelectric pump with “E”-shaped
valve found from sub-experiments
Jianhui ZHANG, Jun HUANG, Xiaoqi HU, Qixiao XI,
Front. Mech. Eng.. 2010, 5 (2): 212-218.
https://doi.org/10.1007/s11465-010-0009-x
Increasing the driving frequency of a piezoelectric vibrator can resolve the bottleneck of low flow in a valve piezoelectric pump. However, a piezoelectric pump of a traditional valve body presents the hysteretic nature of the valve, and macroscopic performance is up-frequency to flow-sharply. This research is to settle the bottleneck mentioned above. First, through the sub-experiment on various parameters of the plate valve of a piezoelectric pump, the reasons why a valve body itself can influence “up-frequency to flow-sharply”, which causes the hysteretic nature of the valve, were discovered. Second, an “E”-shaped valve and piezoelectric pump with an “E”-shaped valve (PPEV) were invented. Finally, the efficiency of PPEV has been proved helpful to reduce hysteretic nature in experiments. Under the similar conditions, compared with traditional pumps, the driving frequency of novel PPEV can be more than 10 times high, and the flow rate also can be several times high.
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Dynamic analysis of free-surface thin film flows
driven by gravity over undulated substrate
Zhaomiao LIU, Xin LIU, Guobin WANG, Hong LIAO,
Front. Mech. Eng.. 2010, 5 (2): 219-225.
https://doi.org/10.1007/s11465-010-0010-4
This paper studies thin film flows with free surfaces driven by gravity through two types of undulated planes: periodically sinusoidal plane and triangle. The substrate plane is fixed and inclined to a certain angle and the flow with a free surface. Through finite element method (FEM), commenced from Navier-Stokes equations and continuity equation, the exact numerical results of free-surface film flows are obtained through discretization solution to finite equations in flowing areas. Based on the numerical calculations, the streamlines and wall shearing stress during the flowing process are visualized via post-proceeding, and the streamlines separation, the onset and evolution of vortex near the substrate boundary during the flow are also analyzed. The influences from the waviness of the substrate planes profile, height of the triangle plane, and change of the film height on film flow dynamics properties are shown.
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Characteristics of metal magnetic memory signals
of different steels under static tension
Yiliang ZHANG, Ruibin GOU, Jimin LI, Gongtian SHEN,
Front. Mech. Eng.. 2010, 5 (2): 226-232.
https://doi.org/10.1007/s11465-010-0012-2
To study the characteristics of metal magnetic memory (MMM) signals of different steels during tensile test, static tension tests were applied to 30 pieces of Q235 and 16MnR base metal and welded specimens. During the various deformation periods, MMM signals are tested, and micrometallographic is observed. Furthermore, the derivative of magnetic intensity (dHp/dx) is analyzed by mathematical and statistical methods to study the macro and micro corresponding relationships and difference among magnetic signals. Results show that despite the different magnetic intensity (Hp) curves of different materials, their dHp/dx patterns in the yielding and necking stages are the same; welded specimens have the similar magnetic signal curves with their base metal, and the welded structure does not interfere with its Hp distribution; different materials have their unique zero point (Hp=0) before being fractured, which is independent of the fracture location; there is a direct relationship between the intragranular slip and the changes of magnetic signals, which indicates the uneven plastic deformation.
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Transfer function solving, simulating and testing
of thermal dynamics characteristics of a ballscrew
Junyong XIA, Bo WU, Youmin HU, Tielin SHI,
Front. Mech. Eng.. 2010, 5 (2): 233-241.
https://doi.org/10.1007/s11465-010-0014-0
Based on the theory of heat transfer, the transfer function between the thermal deformation of any point on the lead screw and the temperature of heat sources of a ballscrew under the influence of multi-changeable heat sources is solved by using the Laplace transform method. By solving the amplitude-frequency characteristics and phase-frequency characteristics of the transfer function, the steady-state response of thermal deformation of the ballscrew is obtained, and the thermal dynamics characteristics of the lead screw under the influence of multi-heat sources are further studied. Comparing with the result of finite-element simulation, the theoretical analyzing result accords with the steady-state part of the finite-element simulating result. Through tests of the steady-state response of thermal deformation, the thermal dynamics characteristics are further studied. The curves of tests by and large accord with the theoretical analyzing result, which shows that the method of transfer function is correct and valid in solving the steady-state response of thermal deformation.
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Improving the performances of ultrasonic motors
using intermittent contact scheme
Jiamei JIN, Jianhui ZHANG, Fu QIAN, Zhenfeng PAN,
Front. Mech. Eng.. 2010, 5 (2): 242-246.
https://doi.org/10.1007/s11465-010-0016-y
Most ultrasonic motors operate in intermittent contact scheme. Their stators drive the rotors (or sliders) when the stators contact the rotors, and the rotors (or sliders) move under an inertia force when the stators and the rotors are separated. The duty cycle of the contact and the “flight” manages motors’ output performance. To obtain a large output force or output velocity, this paper proposes a concept using the alternative work of a multi-stator or the multi-driving end of a single stator. The method can avoid larger noise, poor efficiency, and lifetime of motors. A novel linear ultrasonic motor using the alternative work of the multi-driving end of a single stator was fabricated and investigated experimentally. The traveling speed without load of the slider is 88 mm/s, and the maximum load is 0.32 N.
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