The Experts below are selected from a list of 38382 Experts worldwide ranked by ideXlab platform
Kunmin Zhao - One of the best experts on this subject based on the ideXlab platform.
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effect of welding parameters on tensile strength of ultrasonic spot welded joints of aluminum to steel by experimentation and artificial neural network
Journal of Manufacturing Processes, 2017Co-Authors: Dewang Zhao, Kunmin ZhaoAbstract:Abstract Aluminum and steel are widely used in automotive and aerospace industries. As a new type of solid-phase welding, ultrasonic spot welding is an effective way to achieve joints of high strength. In this paper, ultrasonic welding was carried out on aluminum-steel dissimilar alloys to investigate the influences of welding parameters on joint strength. Designed and conducted a 3-factor, 3-level comprehensive test. The analyses of test results show that there are 3 kinds of fractures on the welding joint with different welding parameters. The highest strength can reach 3910 N. Clamping force and Vibration Amplitude not significantly impact the tensile strength. Vibration time significantly impact the tensile strength although its significance level is close to the threshold. The interaction between welding parameters all can significantly impact the tensile strength. The artificial neural network optimized by Genetic Algorithm was used to establish an analytical model. The supplemental experiment and residual analysis were conducted to verify the accuracy of the analytical model. The analytical model show that with the increase of clamping force, the changes of optimal and minimum strength are limited, but the range of welding parameters to obtain a higher strength change significantly; the optimal welding parameters from lower Vibration Amplitude and higher Vibration time shifts towards to higher Vibration Amplitude and shorter Vibration time gradually; for 0.3 Mpa clamping force, the influences of Vibration Amplitude and Vibration time on tensile strength are not significant.
Dewang Zhao - One of the best experts on this subject based on the ideXlab platform.
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effect of welding parameters on tensile strength of ultrasonic spot welded joints of aluminum to steel by experimentation and artificial neural network
Journal of Manufacturing Processes, 2017Co-Authors: Dewang Zhao, Kunmin ZhaoAbstract:Abstract Aluminum and steel are widely used in automotive and aerospace industries. As a new type of solid-phase welding, ultrasonic spot welding is an effective way to achieve joints of high strength. In this paper, ultrasonic welding was carried out on aluminum-steel dissimilar alloys to investigate the influences of welding parameters on joint strength. Designed and conducted a 3-factor, 3-level comprehensive test. The analyses of test results show that there are 3 kinds of fractures on the welding joint with different welding parameters. The highest strength can reach 3910 N. Clamping force and Vibration Amplitude not significantly impact the tensile strength. Vibration time significantly impact the tensile strength although its significance level is close to the threshold. The interaction between welding parameters all can significantly impact the tensile strength. The artificial neural network optimized by Genetic Algorithm was used to establish an analytical model. The supplemental experiment and residual analysis were conducted to verify the accuracy of the analytical model. The analytical model show that with the increase of clamping force, the changes of optimal and minimum strength are limited, but the range of welding parameters to obtain a higher strength change significantly; the optimal welding parameters from lower Vibration Amplitude and higher Vibration time shifts towards to higher Vibration Amplitude and shorter Vibration time gradually; for 0.3 Mpa clamping force, the influences of Vibration Amplitude and Vibration time on tensile strength are not significant.
Michael De Leon - One of the best experts on this subject based on the ideXlab platform.
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parametric study in similar ultrasonic spot welding of a5052 h32 alloy sheets
Journal of Materials Processing Technology, 2015Co-Authors: Hyungseop Shin, Michael De LeonAbstract:Abstract Ultrasonic spot welding (USW) is a solid-state joining process highly applicable to lightweight alloy materials with high diffusivity rates in the melt state. To improve the understanding of the USW process and to enhance the weld strength in similar Al alloy welding, this work focused on a parametric study using some process parameters such as Vibration Amplitude and welding time. Experiments were conducted using lateral-drive USW machine operating in time control mode. Weld quality of USWed joint was analyzed based on the weld strength obtained by lap-shear tests and the fracture pattern subsequently characterized. Mixed fracture pattern of shear and pull-out exhibited a higher lap-shear failure load, while solely shear and pull-out was a distinct fracture pattern in lower lap-shear failure load. Shorter welding time was needed for higher Vibration Amplitude to generate enough temperature and to prevent over welding. Joint microstructures revealed that longer welding time produced over welding which gave short but intensified weld interface waviness, resulting to a shorter fracture path. The horn and anvil tip surface patterns influenced on the variation in temperature rise measured at the weld part and the extent of part marking/sticking. The temperature rise measured on the weld surface was useful to determine over welding condition. Weldability map of USWed Al alloy sheets could be constructed from the results of weld strength and fracture type, and an effective welding energy input was determined from welding process parameters combination.
Hyungseop Shin - One of the best experts on this subject based on the ideXlab platform.
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parametric study in similar ultrasonic spot welding of a5052 h32 alloy sheets
Journal of Materials Processing Technology, 2015Co-Authors: Hyungseop Shin, Michael De LeonAbstract:Abstract Ultrasonic spot welding (USW) is a solid-state joining process highly applicable to lightweight alloy materials with high diffusivity rates in the melt state. To improve the understanding of the USW process and to enhance the weld strength in similar Al alloy welding, this work focused on a parametric study using some process parameters such as Vibration Amplitude and welding time. Experiments were conducted using lateral-drive USW machine operating in time control mode. Weld quality of USWed joint was analyzed based on the weld strength obtained by lap-shear tests and the fracture pattern subsequently characterized. Mixed fracture pattern of shear and pull-out exhibited a higher lap-shear failure load, while solely shear and pull-out was a distinct fracture pattern in lower lap-shear failure load. Shorter welding time was needed for higher Vibration Amplitude to generate enough temperature and to prevent over welding. Joint microstructures revealed that longer welding time produced over welding which gave short but intensified weld interface waviness, resulting to a shorter fracture path. The horn and anvil tip surface patterns influenced on the variation in temperature rise measured at the weld part and the extent of part marking/sticking. The temperature rise measured on the weld surface was useful to determine over welding condition. Weldability map of USWed Al alloy sheets could be constructed from the results of weld strength and fracture type, and an effective welding energy input was determined from welding process parameters combination.
Kentaro Nakamura - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of compressible fluid flow in an ultrasonic suction pump
Ultrasonics, 2016Co-Authors: Yuji Wada, Daisuke Koyama, Kentaro NakamuraAbstract:Abstract Characteristics of an ultrasonic suction pump that uses a vibrating piston surface and a pipe are numerically simulated and compared with experimental results. Fluid analysis based on the finite-difference time-domain (FDTD) routine is performed, where the nonlinear term and the moving fluid–surface boundary condition are considered. As a result, the suction mechanism of the pump is found to be similar to that of a check valve, where the gap is open during the inflow phase, and it is nearly closed during the outflow phase. The effects of Reynolds number, Vibration Amplitude and gap thickness on the pump performance are analyzed. The calculated result is in good agreement with the previously measured results.
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an analysis of jumping and dropping phenomena of piezoelectric transducers using the electrical equivalent circuit constants at high Vibration Amplitude levels
Japanese Journal of Applied Physics, 2000Co-Authors: Mikio Umeda, Kentaro Nakamura, Sadayuki Takahashi, Sadayuki UehaAbstract:This paper presents an analysis of the jumping and dropping phenomena of piezoelectric transducers, using the electrical equivalent circuit constants at high Vibration Amplitude levels of resonance based on the electrical transient response technique. The calculated frequency characteristics well simulated the measured ones driven by a constant voltage source. It is clarified from the results that the jumping and dropping phenomena are caused mainly by the nonlinear behavior of the elastic constant at high Vibration Amplitude levels. The effects of the loss, the voltage and the driving method are also discussed.
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effects of Vibration stress and temperature on the characteristics of piezoelectric ceramics under high Vibration Amplitude levels measured by electrical transient responses
Japanese Journal of Applied Physics, 1999Co-Authors: Mikio Umeda, Kentaro Nakamura, Sadayuki UehaAbstract:This paper presents a characteristic evaluation of piezoelectric ceramics at high Vibration Amplitude levels of resonance, based on the electrical transient response technique. Low-Q and high-Q materials are measured, and the effect of Vibration stress is obtained without affecting temperature. It is revealed that for low-Q materials an increase of loss is caused mainly by the Vibration stress, while for high-Q materials, it is caused by both the Vibration stress and the temperature increase. The results show that in some high-Q materials, it is meaningless to evaluate the piezoelectric materials at low Vibration level, since the characteristics change variously at high Vibration levels. The force factor is changed mainly by the temperature, although its behavior is different, depending on material composition.
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effects of a series capacitor on the energy consumption in piezoelectric transducers at high Vibration Amplitude level
Japanese Journal of Applied Physics, 1999Co-Authors: Mikio Umeda, Kentaro Nakamura, Sadayuki UehaAbstract:In this paper, a driving method for low-loss generation in piezoelectric transducers at a high Vibration Amplitude level is presented. First, we analyze the power consumption of several loss mechanisms of piezoelectric transducers using an electrical equivalent circuit model. In this model, loss due to piezoelectric effect is explicitly represented by a series resistor, and pure dielectric loss is separately denoted by a parallel resistor. Mechanical loss is represented by a series resistor in the mechanical arm. The reason for the high efficiency at the anti resonance frequency is explained by this analysis. Next, the effect of an external series capacitor is discussed by comparing the experiment with the calculation, based on the equivalent circuit model for the high Vibration Amplitude level. By using the external series capacitor, the loss generated at the high Vibration Amplitude was significantly reduced without a large increase in electrical impedance.
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the measurement of high power characteristics for a piezoelectric transducer based on the electrical transient response
Japanese Journal of Applied Physics, 1998Co-Authors: Mikio Umeda, Kentaro Nakamura, Sadayuki UehaAbstract:In this paper, the theoretical and experimental considerations on the high-power characteristics of a piezoelectric transducer are presented. First, we propose a new measurement method for the large Vibration Amplitude region using an electrical transient response to eliminate the effect of temperature rise. Then, a new loss mechanism concerning the piezoelectric effect is explained by observing the relationship between the Vibration velocity and the current and their harmonics. A `piezoelectric loss' is newly introduced in the equivalent circuit model to describe the real loss phenomena clearly.
