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1.
A direct formulation of the boundary element method using complex variable functions for two-dimensional elastoplastic analysis has been developed. Based on the initial stress approach and complex potential fundamental solutions, the method simplified the computer program and reduced the input data and the order of the equation system greatly; the function of the computer program has been improved and the singular solution behaviour in the yield region near the boundary is eliminated. Two numerical examples have shown that the method can be used in practical applications of elastoplastic analysis in engineering. 相似文献
2.
Dong-Ho Kim Gabseong Lee Dong-Hoon Choi Jin-Ho Choi Sang Hoon Lee Byung Man Kwak 《Journal of Mechanical Science and Technology》2008,22(6):1052-1057
Moment methods, which are powerful and simple techniques for analyzing the reliability of a system, evaluate the statistical
moments of a system response function and use information from the probability distribution in the analysis. The full factorial
moment method (FFMM) performs reliability analysis by using a 3n full factorial design of experiments (DOE) and the Pearson system for random variables. To overcome the inefficiency of FFMM,
the response surface moment method (RSMM) has been proposed, which is based on a response surface model (RSM) that is updated
by adding cross product terms into the simple quadratic model. In this paper, we propose the enhanced RSMM (RSMM+) that modifies
the procedure of selecting a cross product term in the RSMM and adds a process of judging whether the response surface model
can be established before performing an additional experiment. We apply the proposed method to several examples and show that
it gives better results in efficiency. 相似文献
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Robotic fiber placement process analysis and optimization using response surface method 总被引:1,自引:0,他引:1
Tauseef Aized Bijan Shirinzadeh 《The International Journal of Advanced Manufacturing Technology》2011,55(1-4):393-404
Unlike traditional materials, composites are carefully designed materials suitable for specific applications. Conventional methods of fabrication of composite structures have proven to be labor intensive and time-consuming. Robotic fiber placement is a composite fabrication technique that increases the flexibility of fiber placement process and allows for the fabrication of more complex structures. This study is aimed at analyzing and optimizing the robotic fiber placement process parameters. Many experiments have been conducted to analyze gas torch temperature, fiber laying head speed, and fiber compaction force and the process is optimized using response surface method. 相似文献
5.
Young Hyun Nam 《Journal of Mechanical Science and Technology》1999,13(2):158-167
Ultrasonic testing uses the directivity of the ultrasonic wave, which propagates in one direction. The directivity is expressed
as the relationship between the propagation direction and its sound pressure. The directivity of an ultrasonic wave is related
to the choice of probe arrangement, testing sensitivity and scanning pitch, and correct measurement of defect size and location.
This paper investigated the directivity of ultrasonic waves, which are scattered from a slit defect located in simulated butt
weld joint using a visualization method. When the defect size was smaller than the wavelengths, clear directivity in the reflected
wave was observed. When the ratio of defect size to wavelength is greater than 1.5, measured directivities almost agree with
the theoretical directivity. The directivity of shear waves scattered from the slit defect varied according to probe direction
(Far defect, Near defect). The angle of reflection wave became similar to angle of incidence as the height of excess metal
in welded joint increased. 相似文献
6.
A side orifice is an important type of hydraulic structure which is used widely in irrigation and waste management systems to divert desired discharges from a main channel or to distribute the flow within the basins. Circular pipes flowing partially full are often used in these systems, but existing predictive relations developed for rectangular channels result in significant error. In the present study, the flow through a side orifice in a circular open-channel is numerically simulated and validated to test the effect of different parameters on the discharge coefficient and propose an appropriate predictive equation. To minimize the number of required simulations and validations, a Response Surface Method-Central Composite Design (RSM-CCD) is employed. Results showed that the discharge coefficient is inversely related to the Froude number (Fr) and the ratio of the side orifice length to the approaching flow water depth. However, any increase in either the ratio of the orifice length to the main channel diameter or the ratio of the lower crest level to the orifice length will increase the discharge coefficient. A new equation is presented to determine the discharge coefficient of side orifice in a circular open-channel using RSM-CCD. The sensitivity analysis showed that all linear terms must considered in the equation but that the interaction terms can be dropped. The maximum error of the equation to predict the training and validation data are 1% and 2% respectively. 相似文献
7.
以压力杆和支座两类零件的加工为例,分析了大型凹球面的数控加工方法.选择以铣代车的加工工艺方案,对不同的刀具、走刀路线进行了分析比较,得到合理的铣削加工方案,并进行了实际加工验证.结果表明:采用合理的以铣代车工艺可提高生产效率和零件加工表面的质量,降低加工成本. 相似文献
8.
A method to integrate the vorticity-velocity form of two-dimensional or axi-symmetric incompressible Navier-Stokes equations
is described. The method employs equi-potential lines and streamlines of an inviscid flow as coordinate lines and the velocity
field is determined from the vorticity distribution with boundary conditions on the normal velocity only, while the tangential
velocities are used as boundary conditions for the vorticity. The results of numerical experiments on time-dependent flow
past an impulsively started circular cylinder and sphere are, then, presented to demonstrate the performance of the scheme.
Numerical results show that the present method is very stable and accurate. 相似文献
9.
Conventional compression bone fracture plates sometimes cause osteoporosis under the plate due to their high rigidity. In
order to prevent the osteopenia, many researchers have attempted various types of bone plates. To meet the same purpose, a
new concept bone plate which have a vicoelastic washer between plate and screw head is introduced. The washer is made of a
biocompatible polymer (ultra high molecular weight polyethylene, UHMWPE). This research was performed first to establish a
more realistic and detailed plated-bone system using finite element method and second to investigate the effect of the UHMWPE
washer on the stress shielding comparing with the conventional plate model. Three-dinensional finite element meshes of the
human femur with the conventional and new concept bone plate were generated and the comparative stress analysis of the stress
shielding was performed with static half-stance loading condition. The results of analysis showed that the new and conventional
bone plate transfer the stress through the bone average 15% and 10% that of the intact bone respecively. However, the local
stress in the bone under the new bone plate have increased about 13-150% that of the conventional bone plate depending on
the region. Earlier preliminary animal studies showed some promising results. It is suggested that the in vivo and FEM results
support the feasibility of the new concept bone plate. 相似文献
10.
Hansen AK Galante M McCarren D Sears S Scime EE 《The Review of scientific instruments》2010,81(10):10D701
Recent laser upgrades on the Hot Helicon Experiment at West Virginia University have enabled multiplexed simultaneous measurements of the ion velocity distribution function at a single location, expanding our capabilities in laser-induced fluorescence diagnostics. The laser output is split into two beams, each modulated with an optical chopper and injected perpendicular and parallel to the magnetic field. Light from the crossing point of the beams is transported to a narrow-band photomultiplier tube filtered at the fluorescence wavelength and monitored by two lock-in amplifiers, each referenced to one of the two chopper frequencies. 相似文献
11.
Yan Yanyan Zhao Bo Liu Junli 《The International Journal of Advanced Manufacturing Technology》2009,43(5-6):462-467
Based on the model of a grain cutting trace in workpiece during two-dimensional ultrasonic assisted grinding, microscopic cutting trace of the grain is analyzed, and the grain cutting trace of spiral line is defined, the motion model of the contact between single abrasive particle and workpiece in a vibration period is established during two-dimensional ultrasonic assisted grinding, and the results show that the grain motion mode of two-dimensional ultrasonic assisted grinding is similar to the rotary cutting mode. Grinding experiments on surface quality of nano-ZrO2 ceramic are carried out using diamond grinding in different condition, both with and without ultrasonic vibration. Experimental results show that the surface quality after two-dimensional ultrasonic assisted grinding is superior to that after diamond grinding, and it is easier for two-dimensional ultrasonic assisted grinding as material removal mechanism employs ductile grinding mode. 相似文献
12.
针对目前在结构可靠性计算中被广泛应用的传统响应面法存在计算量大,精确度不高,容易产生奇异解,必须知道功能函数才能计算等问题.首先根据最小二乘原理,在只需知道设计验算点对应的功能函数值的情况下,利用权函数的紧支性、非负性、光滑性、递减性等性质,在影响域内应用选取的设计验算点,提出了用移动最小二乘法通过迭代生成响应面函数,然后结合一阶可靠性方法,计算结构的最大失效点与可靠性指标.通过反复迭代,直到计算的相邻两次的可靠性指标满足所给的误差为止.给出了切实可行的算法,该算法不需要知道功能函数,甚至不需要知道功能函数的类型就可以进行计算.算例表明,文中方法以较少的迭代次数,可以获取高精度的最大失效点与可靠性指标. 相似文献
13.
Anish Sachdeva Sharanjit Singh Vishal S. Sharma 《The International Journal of Advanced Manufacturing Technology》2013,64(9-12):1505-1516
Selective laser sintering (SLS) has been recognized as one of the best rapid prototyping (RP) technique for producing solid models, directly from computer-aided design data by fussing together different layers with the help of laser light. Further, RP has traditionally been used for producing a solid model for visualization purpose and assessing kinematic functionality. So, the model is required to have superior mechanical integrity and surface quality for handling and model testing. This study investigates surface roughness (SR) of parts produced by SLS process. The empirical models have been purposed to predict the feasibility of different process parameters viz., laser power, scan spacing, bed temperature, hatch length, and scan count on SR. Further, these parameters have been optimized using face-centered central composite design with response surface methodology. The optimized parameters have been verified by conducting confirmation experiments. 相似文献
14.
Luo Y Heidbrink WW Burrell KH Kaplan DH Gohil P 《The Review of scientific instruments》2007,78(3):033505
Fast ions are produced by neutral beam injection and ion cyclotron heating in toroidal magnetic fusion devices. As deuterium fast ions orbit around the device and pass through a neutral beam, some deuterons neutralize and emit D(alpha) light. For a favorable viewing geometry, the emission is Doppler shifted away from other bright interfering signals. In the 2005 campaign, we built a two channel charge-coupled device based diagnostic to measure the fast-ion velocity distribution and spatial profile under a wide variety of operating conditions. Fast-ion data are acquired with a time resolution of approximately 1 ms, spatial resolution of approximately 5 cm, and energy resolution of approximately 10 keV. Background subtraction and fitting techniques eliminate various contaminants in the spectrum. Neutral particle and neutron diagnostics corroborate the D(alpha) measurement. Examples of fast-ion slowing down and pitch angle scattering in quiescent plasma and fast-ion acceleration by high harmonic ion cyclotron heating are presented. 相似文献
15.
Numerical analysis of projection welding on auto-body sheet metal using a coupled finite element method 总被引:1,自引:1,他引:0
W.-F. Zhu Z.-Q. Lin X.-M. Lai A.-H. Luo 《The International Journal of Advanced Manufacturing Technology》2006,28(1-2):45-52
A comprehensive finite element method employing a subroutine to link up submodules of commercial code ANSYS is proposed to
perform analysis of projection welding in quantitative detail. In order to solve the complexity due to dynamic changes in
heat and electrical current flow paths, as well as temperature-dependent material properties, information about contact interfaces
and the geometry of the projection areas have been taken into account. By updating parameter information among these submodules
in an incremental manner, a truly thermal-electrical-mechanical coupled numerical analysis is realized for projection welding
simulation. A case study of an automotive door assembly welding process is carried out and a series of experiments is conducted
to confirm the validity of the newly developed method. The agreement between the experimental and numerical results is satisfactory,
indicating that the incrementally coupled finite element method may be suitable for projection welding research. Finally,
future work to extend this method in optimizing projection welding process design is also presented. 相似文献
16.
Behnam Kamrani Viktor Berbyuk Daniel Wäppling Uwe Stickelmann Xiaolong Feng 《The International Journal of Advanced Manufacturing Technology》2009,44(1-2):201-210
This paper is concerned with a new approach for optimal placement of a prescribed task in the workspace of a robotic manipulator. The approach is resulted by applying response surface method on concept of path translation and path rotation. A robotic optimization tool based on this approach is developed as an add-in to RobotStudio. The methodology has been carefully verified by optimizing the position of several kinds of industrial robots and paths in four showcases to attain minimum cycle time. The results indicate that an increase in productivity up to 37%, compared to the admissible location with the highest cycle time, is achieved by optimally positioning the task in the robot workspace. 相似文献
17.
Titov Yu. V. Logacheva A. I. Belan D. Yu. Kuznetsov A. A. 《Russian Engineering Research》2017,37(5):462-463
A high-speed method of powder production is analyzed. X-ray, chemical, and granulometric analysis indicates that the particle size of the powder obtained depends on the grinding conditions. The properties of the powder are basically the same as those of the initial sample.
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A study on the optimization method for a multi-body system using the response surface analysis 总被引:1,自引:0,他引:1
Sung-Pil Jung Tae-Won Park Kab-Jin Jun Ji-Won Yoon Soo-Ho Lee Won-Sun Chung 《Journal of Mechanical Science and Technology》2009,23(4):950-953
An optimization method, which minimizes the characteristic value of a system using response surface analysis, is presented.
Plackett-Burman design is used as a screening method. Using the response surface analysis, second order recursive model function
is estimated as an objective function. To verify the reliability of the model function, an F-test based on the analysis of
variances table is used. Lastly, the sequential quadratic-programming method is used to find the value of design parameters.
By applying the preceding procedure to a multi-body dynamic model, the optimization process presented in this study is verified.
This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008.
Sung Pil Jung received a B.S. degree in Mechanical Engineering from Ajou University in 2006. Currently he is a Ph.D candidate at Ajou University
in Suwon, Korea. Mr. Jung’s research interests are in the area of multi-body & structural dynamics, optimization and computer
aided engineering.
Tae Won Park received a B.S. degree in Mechanical Engineering from Seoul University. He then went on to receive his M.S. and Ph.D. degrees
from the University of Iowa. Dr. Park is currently a Professor at the School of Mechanical Engineering at Ajou University
in Suwon, Korea. 相似文献