Advanced Materials Research Vols. 538-541

Abstract: In the cast-resin dry-type transformer design, the determination of winding hottest-spot temperature rise is very important. It determines the safe and cost of transformers. In this paper, a thermal model for analysis of the hottest-spot temperature distribution of cast-resin dry-type transformer has been introduced. The model is based on electrical analogy method and a current source is used to represent the thermal flow source of windings, and a nonlinear resistor is used to represent the effect of air in duct. A 500kVA cast-resin dry-type transformer has been selected and experiment is carried out to demonstrate the model

Abstract: This article took the PC main board as a research object and simulated how to optimize the position of the desktop main board pads. The static stress analysis was executed using ABAQ -US/Standard. The objective was to reduce the local deformation of computer main board occurs when the connector was inserted and extracted during the assembly process, preventing the chips and capacitances on the main board from becoming invalid. The simulation results showed that the FEA method with Abaqus can be used to predict the main board performance and structure optimization.

Abstract: A new numerical simulation system of a flexible Euler beam with imbedded fluid subsystem, an expansive FLUENT UDF computing system, has been proposed and investigated in this paper. The results of numerical simulation basically matched the experiment. The shape of fluid free surface, the pressure field and the velocity field of the field commendably opened out the movement law of fluid in cavum and the characteristic of fluid-beam interworking, and explain the interior principle and validity of reducing vibration of the Interior Inlay Viscous Fluid Unit (IVFU) towards the flexible beam.

Abstract: To solve the problems of complex bending parts forming, such as low efficiency and accuracy, and loss of modification experience data, the algorithm of three parameters segment springback modification (TPSSM) based on arc approximation is presented in this paper. Firstly, the centroid line is divided into several arc sections according to the requirement and each section is modified based on presumptive correcting factor of radius, torsion and torsion angle. Then based on UG re-development, the program and UI of TPSSM are developed with UG/Open API and MFC. Finally, experimental results show that this method can effectively realize springback modification of bending parts, which is worthy for practical engineering project.

Abstract: This paper proposes a fast and convenient method to inverse the material performance parameters in stamping forming. This method effectively combined with the FEM and the genetic algorithm. The reverse objective function was constructed with the thickness which is easily measured from the stamped parts, and then a genetic algorithm was programmed; The thickness-sensitive material performance parameters can be acquired through the orthogonal experiment, then these material parameters can be inversed by the self-programming genetic algorithm. Finally, a stamping case proves this method is precise, rapid and valid.

Abstract: The HCCI/carbon steel bimetal composite hammer was prepared by bimetal liquid cast process and the effect of cooling rate, which is obtained by different mold material, on the microstructures of hypereutectic HCCI was studied. The results show that the primary carbides and eutectic carbides are refined with the increase of cooling rate. Good metallurgical combination of the HCCI/carbon steel bimetal hammer can be reached by bimetal liquid cast process with fast cooling mold.

Abstract: Wrinkling and cracking are two major problems of the automobile inner panel. In this study, the stamping process of an A pillar inner panel is studied with the finite element (FE) method, aimed at avoiding drawbacks due to wrinkling and cracking. The established numerical model is proved accurate by comparing the numerical final configuration to the real part. Then the material flow of the blank is analyzed. It is concluded that blocking of material flow is the main reason for those two pathologies. Thus, a gap design is suggested to minimize the concerned defects. According to the numerical results, after optimizing, the inner panel is free from formability problems.

Abstract: In order to optimize the process parameters of continuous casting hollow billet with multi-electromagnetic fields, the solidification process of the continuous casting hollow billet was studied by the numerical simulation method, the results show that: 1) when only solenoid coil is imposed on outside of the outer-mold, it generates a lot of joule heat near the outer-side surface of hollow billet and leads to the uneven thickness of the solidified shell which is easily cause the crack defect. 2) when only traveling stirring electromagnetic field is imposed in the inside of the inner-mold, it can homogenize the temperature distribution of the molten metal and decrease the sump height, but it can also result in the uneven thickness of the solidified shell because of the nonuniform flow of molten metal. 3) when the above two kinds of electromagnetic field are applied simultaneously, the multi-electromagnetic fields can improve the homogeneous thickness of the solidified shell and decrease the sump height which is better for the high casting velocity and hollow billet quality.

Abstract: The effect of partitioning process of quenching-partitioning-tempering (Q-P-T) process on hardness and microstructure were investigated. The 1-step Q-P-T and 2-step Q-P-T heat treatment were designed and carried out. The microstructure and carbides were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) patterns. Results showed that compared with 1-step Q-P-T heat treatment, more amount of retained austenite was obtained by 2-step Q-P-T heat treatment, however, the carbides were bigger in size and the hardness was lower.

Abstract: the modern Inverter-driven technology has been applied in energy-saving control for injection molding machine. Aimming at the complex control of system because of its multiple input multiple output, strongly nonlinearity, some volatility parameters and uncertainty factor , the adaptive fuzzy PID compound control is put forward from the viewpoint of energy-conditioning. Using the above method, the control system have better dynamic characteristics and stability, strong robustness and adaptability. Experiment results show that the method can effectively improve energy-saving technology for the injection molding machine.