共查询到20条相似文献,搜索用时 15 毫秒
1.
对TC4钛合金单面修饰激光焊接接头进行激光冲击强化,对比强化前后焊接接头的疲劳寿命,在光学显微镜和扫描电镜下观察断口疲劳断裂特征,并从焊接接头的显微硬度、微观组织、残余应力分布等方面综合分析激光冲击强化对TC4钛合金单面修饰激光焊接接头的强化机理。试验结果表明:未强化和强化试样均在焊缝咬边处萌生疲劳裂纹,强化试样疲劳寿命是未强化试样疲劳寿命的3.77~9.15倍,强化试样焊缝咬边处马氏体细化,显微硬度提高,焊缝表面呈残余压应力分布,焊缝咬边处残余压应力达-564.37±9.85MPa。晶粒细化和高幅值残余压应力综合作用下抑制了焊缝咬边处疲劳裂纹的萌生,且增大了裂纹扩展阻力,从而提高了焊接接头疲劳性能。 相似文献
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Chen Zhixiang Song Yonglun Zhang Jun Zhang Wanchun Jiang Li Xia Xuxin 《Frontiers of Mechanical Engineering in China》2007,2(2):218-223
A laser vision sensing based on the adaptive tungsten inert gas (TIG) welding system for large-scale aluminum alloy components
was established to fit various weld groove conditions. A new type of laser vision sensor was used to precisely measure the
weld groove. The joint geometry data, such as the bevel angle, the gap, the area, and the mismatch, etc., aided in assembling
large-scale aerospace components before welding. They were also applied for automatic seam tracking, such as automatic torch
transverse alignment and torch height adjustment in welding. An adaptive welding process was realized by automatically adjusting
the wire feeding speed and the welding current according to the groove conditions. The process results in a good weld formation
and high welding quality, which meet the requirements of related standards.
Translated from Journal of Beijing University of Technology, 2006, 32(8): 714–718 [译自: 北京工业大学学报] 相似文献
4.
A novel soft-switching twin arc pulse MAG welding inverter 总被引:1,自引:0,他引:1
Wang Zhenmin Xue Jiaxiang Wang Fuguang Huang Shisheng 《Frontiers of Mechanical Engineering in China》2007,2(2):224-227
The high-speed double wire pulse metal-gas arc (MAG) welding process possesses advantages of automation and high efficiency
and quality. Thus, it attracts much more attention nowadays. To meet the requirements of the double wire pulse MAG welding
process, a novel double wire pulse MAG welding inverter integrated with technologies, such as soft-switching, double closed
loop control, and synchronic control, is produced. A complete performance test was done for the pulsed MAG welding power supply
by using a computer testing platform. The results of the experiment indicate that the novel welding inverter has an excellent
performance both in the dynamic and the static characteristics. Also, the synchronic control between the master inverter and
the slave inverter is reliable.
Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(7): 31–34, 59 [译自: 华南理工大学学报 (自然科学版)] 相似文献
5.
Wang Zhanshan Ma Shanshan Ma Yan Zhao Min Liu Hengbiao 《Frontiers of Mechanical Engineering in China》2007,2(4):468-473
The transfer characteristics of an atomic beam and the effect of laser were investigated in this paper. In the application
of knife-edge technique, the temperature of atoms through laser cooling was measured. Results indicate that, after atoms are
emitted from an atomic oven, the longer the atoms move, the worse the distribution of the atomic beam shows, regardless the
laser cooling is taken or not. Laser cooling can reduce the transverse velocity of the atomic beam to several orders of magnitude
and also increase the uniformity of an atomic beam. Knife-edge technique can measure the temperature of an atomic beam through
laser cooling. The measurement accuracy depends on the pixel size of the charge coupled device (CCD), which is used for the
fluorescent imaging of the atomic beam. The results are very important for the future experiments of laser cooling.
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Translated from Optics and Precision Engineering, 2006, 14(1): 63–69 [译自: 光学精密工程] 相似文献
6.
Xuyue Wang Weixing Xu Hua Chen Jinsong Wang 《Frontiers of Mechanical Engineering in China》2008,3(3):293-298
Based on the basic platform of BP neural networks, a BP network model is established to predict the bending angle in the laser
bending process of an aluminum alloy sheet (1–2 mm in thickness) and to optimize laser bending parameters for bending control.
The sample experimental data is used to train the BP network. The nonlinear regularities of sample data are fitted through
the trained BP network; the predicted results include laser bending angles and parameters. Experimental results indicate that
the prediction allowance is controlled less than 5%–8% and can provide a theoretical and experimental basis for industry purpose.
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Translated from Optics and Precision Engineering, 2007, 15(6): 915–921 [译自: 光学精密工程 相似文献
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T. Ussing L. V. Petersen C. B. Nielsen B. Helbo L. Højslet 《The International Journal of Advanced Manufacturing Technology》2007,33(1-2):198-205
The use of laser welding for joining micro parts has experienced a substantial increase in popularity during recent years.
Specifically translucent microfluidic devices are assembled using laser welding; however, a major issue is the laser beam
size of commercially available laser-welding equipment and thus the resulting welding seam size, which may be orders of magnitude
larger than microfluidic channels and structures. We have successfully achieved extremely small welding seams using focussed
low-power laser diodes. Commercial laser welding stations for polymer assembly will typically operate in the power-region
15–50 Watts. The focussed laser beam will have a size of typically 500 μm × 500 μm and may, depending on optical configuration,
be up to several mm2. The resulting welding-seam will thus be in the area of 300–600 μm depending on beam energy distribution; additionally the
melt will spread to unheated areas due to capillary forces. As microfluidic channels are in 20–100 μm regions, even a very
limited amount of stray melt may completely fill a part of a channel and thus render it useless. We have used commercially
available “single-die” laser-diodes of optical power 200–500 mW. The beam has been focussed and directed using simple optical
installations, resulting in a beam-size in the area of 50 μm × 5 μm full width half maximum (FWHM) We have achieved firm welding
seams of width <10 μm, with a welding speed of 15 mm/s and with virtually no noticeable spread of melt. 相似文献
9.
Study of mechanism of activating flux increasing weld penetration of AC A-TIG welding for aluminum alloy 总被引:1,自引:0,他引:1
When multi-component flux AF305 is used as surface activating flux for an aluminum alloy, the weld penetration of activating
flux-tungsten inert-gas (A-TIG) welding is over two times more than that of conventional TIG welding. Using A-TIG welding
with the modes of alternating current (AC), direct current electrode negative (DCEN) and direct current electrode positive
(DCEP), respectively, the flux differently affects weld penetration when the polarity is different. After studied the effect
of compelled arc constriction on weld penetration of AC welding, it is believed that the constriction of the whole arc root
is not the main mechanism that flux AF305 dramatically improves weld penetration. The penetration has a relationship with
the separate distribution of slag on the weld surface. Then, an observation of scanning electron microscopy (SEM) and an electronic
data systems (EDS) analysis of slag were performed respectively. The separate distribution of slag on the weld pool during
welding and the great constriction of arc spots were confirmed by TIG welding with helium shielding gas. The relationship
between slag distribution and weld penetration was studied by adding aluminum powder into flux AF305 to change the distribution
of slag. During welding, the separate distribution of slag on the weld pool results in the great constriction of arc spots,
an increase in arc spot force, and an increase in Lorentz force within the arc and weld pool. Finally, the weld penetration
is increased.
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Translated from Chinese Journal of Mechanical Engineering, 2006, 42(5): 45–49 [译自: 机械工程学报] 相似文献
10.
Hongxia Zhang Wuyi Chen Zhitong Chen 《Frontiers of Mechanical Engineering in China》2008,3(2):139-145
The grindability of high-temperature alloy by using ceramic alumina wheels is studied on the basis of extensive analysis of
the grinding force, grinding temperature, surface roughness and topography of ground surfaces, residual stress, hardness distribution
of surface layer, and morphology of the surface layer from a metallographic point of view. The grinding burn mechanism of
high-temperature alloy is unveiled and the feasible grinding parameters to avoid burning are analyzed. Some conclusions are
obtained as follows. Increasing the grinding depth or the wheel velocity makes grinding temperature and residual tensile stress
of the surface rise, which deteriorates the surface topography. Appropriate liner velocity of the wheel is 18–22 m/s and the
depth of grinding should not exceed 0.02 mm in grinding GH2132 alloy with ceramic alumina wheels to assure the surface quality.
When a
p increases enough to cause grinding burn, the strengthening effect of particles γ′ in γ base decrease and the micro-hardness of the surface is obviously lower than that of the base material, which deteriorates
the mechanical properties and heat resistance of GH2132 alloy. Results provide a theoretical and experimental basis for technical
optimization in the grinding of high-temperature alloy with high efficiency and high quality. 相似文献
11.
This paper presents an optimization model for rotor blades of horizontal axis wind turbines. The model refers to the wind
speed distribution function on the specific wind site, with an objective to satisfy the maximum annual energy output. To speed
up the search process and guarantee a global optimal result, the extended compact genetic algorithm (ECGA) is used to carry
out the search process. Compared with the simple genetic algorithm, ECGA runs much faster and can get more accurate results
with a much smaller population size and fewer function evaluations. Using the developed optimization program, blades of a
1.3 MW stall-regulated wind turbine are designed. Compared with the existing blades, the designed blades have obviously better
aerodynamic performance.
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Translated from Journal of Shantou University (Natural Science), 2006, 21(1): 44–49 [译自: 汕头大学学报 (自然科学版)] 相似文献
12.
Based on the Darcy fluid model, by considering the effects of viscous dissipation due to the interaction between solid skeleton
and pore fluid flow and thermal conduction in the direction of the fluid flow, the thermally developing forced convection
of the local thermal equilibrium and the corresponding thermal stresses in a semi-infinite saturated porous plate channel
are investigated in this paper. The expressions of temperature, local Nusselt number and corresponding thermal stresses are
obtained by means of the Fourier series, and the distributions of the same are also shown. Furthermore, influences of the
Péclet number (Pe) and Brinkman number (Br) on temperature, Nusselt number (Nu) and thermal stress are revealed numerically.
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Translated from Journal of Lanzhou University (Natural Science Edition), 2006, 42(2): 114–119 [译自: 兰州大学学报(自然科学版)] 相似文献
13.
Chen Yangzhi Xing Guangquan Peng Xuefei Liu Wenguang Yao Huaping 《Frontiers of Mechanical Engineering in China》2007,2(1):94-98
The volume of an in-tube micro robot is small and its interior space is very limited. However, conventional transmission methods
are unfit to drive in-tube micro robots. A novel micro drive mechanism called the micro-elastic-meshing-wheel is presented
in this paper. It can be used for transmitting power and locomotion between two shafts, which are upright and cross in a micro
space. The mechanical model of the novel drive mechanism is built, and the maximal transmission force is deduced. Then, sufficient
experiments are carried out to test maximal transmission force produced by the novel drive mechanism. The calculation and
experiment results show that the novel drive mechanism can transmit sufficient power to in-tube micro robots.
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Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(7): 45–49 [译自: 华南理工大学学报 (自然科学版)] 相似文献
14.
A scanning mode is the key technology in a laser metal deposition shaping (LMDS) fabrication process. On the basis of the
analysis of existing scanning modes and their influences on the fabrication efficiency and the quality of parts, some disadvantages
of them are pointed out. A new kind of subarea-parallel scanning mode for LMDS based on a subdividing profiled outline into
monotonous polygon subareas is presented. First, based on the principle of point visibility, inner loops are eliminated, and
simple polygons are subdivided into monotonous polygons with the minimal zones. Second, the parallel scanning paths of all
monotonous polygon subareas are finished, which diminishes the length of the scanning line. The practical application shows
that the scanning mode can enhance the fabrication efficiency and quality.
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Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 170–175 [译自: 机械工程学报] 相似文献
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Liu Xiancui Su Lanhai Li Zhongfu Fu Zhilin Zhang Qingdong He Chun 《Frontiers of Mechanical Engineering in China》2007,2(3):297-300
Research into plate elongation distribution between the tension leveler and temper mill for pickling line 2030 at Baosteel
is conducted. The study, which involved performance testing of mechanics, is designed at different elongation distributions
and analyzed from many aspects. Finally, the optimal elongation of the tension leveler and temper mill is given.
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Translated from Journal of University of Science and Technology Beijing, 2005, 27(5): 609–612 [译自: 北京科技大学学报] 相似文献
17.
Yinnan Yuan Deqing Mei Zhong Wang Tian Zhang 《Frontiers of Mechanical Engineering in China》2008,3(2):189-192
The combustion and heat release of engines using diesel fuel and bio-diesel fuel have been investigated. The results illustrate
that the combustion happens in advance and the ignition delay period is shortened. The initial heat release peak declines
a little, the corresponding crankshaft angle changes in advance, and the combustion duration is prolonged. The economic performance
and emission features of diesel engines using diesel fuel and bio-diesel fuel are compared. The results also show that the
specific fuel consumption of bio-diesel increases by about 12%. The emissions, such as CO, HC, and particulate matter decrease
remarkably whereas NO
x
increases a little.
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Translated from Journal of Jiangsu University (Natural Science Edition), 2006, 27(3): 216–219 [译自: 江苏大学学报(自然科学版)] 相似文献
18.
A dynamical sliding-mode controller is devised to track the output of mobile manipulators. During the investigation, firstly
a reduced dynamic model considering the dynamics of the driving motor is developed for mobile manipulators. Then, the system
is decomposed into four lower-dimensional subsystems by means of diffeomorphism and nonlinear input transformation. Moreover,
a design method of the dynamical sliding-mode controller that is applied to the output tracking of mobile manipulators is
proposed. The simulation results indicate that the dynamical sliding-mode controller can not only track the given trajectory
correctly but also reduce the chattering of sliding-mode control system considerably.
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Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(6): 29–33 [译自: 华南理工大学学报 (自然科学版)] 相似文献
19.
An energy reclaiming suspension is proposed to reclaim vibration energy in the suspension. To study its riding performance
and reclaiming energy performance, a hydraulic energy reclaiming device prototype is produced and its mechanical behavior
is analyzed and tested according to the hydraulic theory. Theoretical analysis shows that mechanical behavior of the energy
reclaiming device is embodied by a viscidity damping parameter and an analogous coulomb damping parameter determined by its
structure; their expressions are obtained. Experimental investigation shows that theoretical predictions agree with test results.
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Translated from Journal of Jiangsu University (Natural Science Edition), 2006, 27(1): 35–39 [译自: 江苏大学学报(自然科学版)] 相似文献
20.
The cutting heat dissipation in chips, workpiece, tool and surroundings during the high-speed machining of carbon steel is
quantitatively investigated based on the calorimetric method. Water is used as the medium to absorb the cutting heat; a self-designed
container suitable for the high-speed lathe is used to collect the chips, and two other containers are adopted to absorb the
cutting heat dissipated in the workpiece and tool, respectively. The temperature variations of the water, chips, workpiece,
tool and surroundings during the closed high-speed machining are then measured. Thus, the cutting heat dissipated in each
component of the cutting system, total cutting heat and heat flux are calculated. Moreover, the power resulting from the main
cutting force is obtained according to the measured cutting force and predetermined cutting speed. The accuracy of cutting
heat measurement by the calorimetric method is finally evaluated by comparing the total cutting heat flux with the power resulting
from the main cutting force.
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Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(11): 1–4 [译自: 华南理工大学学报(自然科学版)] 相似文献