Advanced Materials Research Vols. 314-316

Abstract: This research focus on the squeals occurred in cutting from the views of tribology. A multi-degree-freedom model was established referring to cylindrical turning. The model was made up of two coupled subsystems — tool and workpiece which coupled through the friction between their contacted surface. The relationship between cutting squeal and friction was studied through experiments, and the coefficients of friction were estimated by experimental data. Then the tribological conditions related to squeal generating were discussed. In the end a method of reducing cutting squeal by lubrication was proposed.

Abstract: The process control mechanism of ARB(accumulative roll bonding) process was studied. Based on micro-plastic theory, the principal stress method of macro-plastic theory and probability theory, theoretical models of rolling force and its standard deviation calculation were established. Moreover, shear deformation was analyzed with the finite element method and the finite element model established was verified through comparing with the experiment. Furthermore, through calculating the rolling force of ARB process of the typical parameters, roll force variation of every cycle was obtained and the theoretical model was verified through comparing with the results of the finite element method. The study in the paper provides analysis method and theory foundation for process control and manufacturing of ARB process.

Abstract: In this paper, Smoothed Particle Hydrodynamics (SPH) was used for the prediction of heat conduction problems in sand cast process. The implementation of solidification modeling in a curved casting based on SPH has been described. The treatment of latent heat was introduced in SPH conduction problem by temperature compensation method, which demonstrated the role of latent heat has a great influence on the heat distribution in the casting. The temperature distribution calculated by SPH provided a great agreement with those computed through numerical software MSC.Marc, which validated the efficiency and precision of SPH simulation of heat transfer problems in sand cast process.

Abstract: Line heating is a complex thermal-mechanical process as many factors affect the final shape of a processed plate. Generally, the temperature field of the processed plate determines the stress field and strain field. To predict the deformation of the processed plate, this paper investigates the effects of different factors on the temperature field during line heating by using design of experiment (DOE). Firstly, a three dimensional thermal elasto-plastic finite element method (FEM) is developed to calculate the temperature field induced by the single-pass oxygen-acetylene line heating. Secondly, the temperature field is analyzed by using fractional factorial design, in which the maximum temperature is selected as the response, and a fishbone diagram is used to overview all influencing factors. After performing a series of numerical experiments selected by using an ortho-gonal array, three main influencing factors are screened out: plate thickness, flow of acetylene and velocity of heat source. Next, the main effects of these factors are discussed. Finally, analytical re-sults indicate that there exist interaction effects among the three main influencing factors. This in-vestigation demonstrates that DOE is an efficient method for study of the temperature field during line heating.

Abstract: A three-dimensional finite element model has been created to study the change rules of temperature field during the laser sintering process of nano-hydroxyapatite powder. The numerical simulation of temperature distribution has been achieved based on the equivalence between the sintering time and the sintering speed. The simulation results show that the temperature declines gradually along the radial direction of the laser spot. At the same time, there was the largest temperature gradient at the edge of the laser spot. The temperature of sintering layer rises with the increase of laser power linearly when the other process parameters are the same. The maximum sintering temperature is 1320°C with laser power of 8.75W, laser spot diameter of 4mm, sintering time of 5s and layer thickness of 0.2mm. The test results verify that nano-hydroxyapatite powder could be sintered under this process condition. It shows that the finite element model can be used to simulate the temperature field during the laser sintering process.

Abstract: In order to avoid tremendous modifications of the die cavity for investment casting of turbo blades, this paper proposed an inverse iterative compensation method that adjusts certain geometric parameters to establish the die-profile. The parameterized modeling is achieved by identifying geometric parameters describing the mean camber line; the optimum-curve die-profile can be obtained based on the inverse iteration algorithm. As a result, the dimension precision of turbo blades can be guaranteed. The applicability of this method is validated using numerical simulation data.

Abstract: The effect of the motional electromagnetic force in the electromagnetic forming circuit on the workpiece velocity is analyzed. The differential equations of unconsidering and considering the motional electromagnetic force in the electromagnetic forming circuit are solved numerically. The results without considering the motional electromagnetic force are unavailable because they violate the law of conservation of energy, while the results with considering the motional electromagnetic force can accurately reflect the electromagnetic forming process. Furthermore, it is found that the electrical energy transforms into the kinetic energy due to the motional electromagnetic force.

Abstract: In the paper, The PVDF piezoelectric sensor was customized and the structure and test circuit of PVDF piezoelectric sensor is introduced. The polyurethane(PUF) reinforced by ultra high molecular weigh polyethylene (UHMWPE) material(UHMWPE-PUF composites) was synthesized. The pressure in UHMWPE-PUF composites under explosion load was measured and shock wave attenuation waveform is gained and the data is analyzed. The studies showed that PVDF piezoelectric firm sensor is suitable to shock wave measurement in material and UHMWPE- PUF composites can improve maximally shock wave attenuation properties of the material and have good applied outlook in the realm of anti-explosion.

Abstract: In this paper, die wear during fine-blanking process of a kind of automobile synchronizer slipper was investigated based on Finite Element Method (FEM) and experiments. The Finite Element (FE) model to simulate the fine-blanking process of the automobile synchronizer slipper was established on the DEFORM-3D software platform, and Archard's wear model was employed to calculate die wear during the process. Meanwhile, mesh refinement and automatic remeshing technique were used during meshing process of the blanked materials and bottom die in order to achieve high accuracy results of FE simulations and improve the computational efficiency. Simulation results have been verified and show good agreement with the real manufacture. In addition, relationships between die wear and the process parameters during fine-blanking process such as pressure pad force, ejector force, blanking speed, blanking clearance, fillet radius of bottom die as well as hardness of bottom die were investigated, respectively via FEM. The simulation results indicate that die wear is in proportion to the pressure pad force, ejector force, blanking speed and fillet radius of bottom die, while in inverse proportion to the blanking clearance and hardness of bottom die, which will provide a reliable reference for the real manufacture and engineering application.

Abstract: In this paper, the model of the engine connection rod is founded by use of UG, and then joined in the ANSYS, applied the Multiphysics module and static structuer analysis function, we can count the stress field of the connection rod and accomplish the evaluate of the mechanical load.