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ARC welding method for bonding steel with aluminum
Zhenyang LU, Pengfei HUANG, Wenning GAO, Yan LI, Hanpeng ZHANG, Shuyan YIN
Front Mech Eng Chin. 2009, 4 (2): 134-146.
https://doi.org/10.1007/s11465-009-0033-x
When welding steel with aluminum, the appearance of intermetallic compounds of Fe and Al will decrease tenacity and increase rigidity, which leads to bad joint performance. A new type of low energy input (LEI) welding technology is introduced which can be used to weld steel with aluminum. Using the technology, brazing was located on the steel side and arc fusion welding on the aluminum side. The less heat input reduces the thickness of intermetallic compounds to 3-4 μm. Tensile strength tests prove that the joint breaks at the heat-affected zone and the strength is higher than 70% of the aluminum’s. Thus, the method can lead to a good performance joint.
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Comparison between four piezoelectric energy harvesting circuits
Jinhao Qiu, Hao Jiang, Hongli Ji, Kongjun ZHU
Front Mech Eng Chin. 2009, 4 (2): 153-159.
https://doi.org/10.1007/s11465-009-0031-z
This paper investigates and compares the efficiencies of four different interfaces for vibration-based energy harvesting systems. Among those four circuits, two circuits adopt the synchronous switching technique, in which the circuit is switched synchronously with the vibration. In this study, a simple source-less trigger circuit used to control the synchronized switch is proposed and two interface circuits of energy harvesting systems are designed based on the trigger circuit. To validate the effectiveness of the proposed circuits, an experimental system was established and the power harvested by those circuits from a vibration beam was measured. Experimental results show that the two new circuits can increase the harvested power by factors 2.6 and 7, respectively, without consuming extra power in the circuits.
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Dynamic characteristics of an NC table with phase space reconstruction
Linhong WANG, Bo WU, Runsheng DU, Shuzi YANG
Front Mech Eng Chin. 2009, 4 (2): 179-183.
https://doi.org/10.1007/s11465-009-0018-9
The dynamic properties of a numerical control (NC) table directly interfere with the accuracy and surface quality of work pieces machined by a computer numerical control (CNC) machine. Phase space reconstruction is an effective approach for researching dynamic behaviors of a system with measured time series. Based on the theory and method for phase space reconstruction, the correlation dimension, maximum Lyapunov exponent, and dynamic time series measured from the NC table were analyzed. The characteristic quantities such as the power spectrum, phase trajectories, correlation dimension, and maximum Lyapunov exponent are extracted from the measured time series. The chaotic characteristic of the dynamic properties of the NC table is revealed via various approaches. Therefore, an NC table is a nonlinear dynamic system. This research establishes a basis for dynamic system discrimination of a CNC machine.
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Analytical approach to robust design of nonlinear mechanical systems
Jian ZHANG, Nengsheng BAO, Guojun ZHANG, Peihua GU
Front Mech Eng Chin. 2009, 4 (2): 203-214.
https://doi.org/10.1007/s11465-009-0022-0
The robustness of mechanical systems is influenced by various factors. Their effects must be understood for designing robust systems. This paper proposes a model for describing the relationships among functional requirements, structural characteristics, design parameters and uncontrollable variables of nonlinear systems. With this model, the sensitivity of systems was analyzed to formulate a system sensitivity index and robust sensitivity matrix to determine the importance of the factors in relation to the robustness of systems. Based on the robust design principle, an optimization model was developed. Combining this optimization model and the Taguchi method for robust design, an analysis was carried out to reveal the characteristics of the systems. For a nonlinear mechanical system, relationships among structural characteristics of the system, design parameters, and uncontrollable variables can be formulated as a mathematical function. The characteristics of the system determine how design parameters affect the functional requirements of the system. Consequently, they affect the distribution of system performance functions. Nonlinearity of the system can facilitate the selection of design parameters to achieve the required functional requirements.
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14 articles
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