Applied Mechanics and Materials Vols. 217-219

Abstract: The paper brings the results of wall thickness distribution analysis of formed part produced by CNC multi-pass conventional metal spinning. The thickness reduction was measured by optical 3D scanning method and the influence of the feed, workpiece geometry and planar anisotropy of the blank on the wall thickness reduction was studied. For experiment design, an orthogonal array L27 was used and ANOVA (Analysis of Variance) was carried out. Based on the results it is determined that the highest reduction of wall thickness is observed in the conical part of the experimental sample. Workpiece geometry is the most important factor which influences the wall thickness variation.

Abstract: Measuring residual stray field (RMF) signals provides a promising tool to analyze the stress in ferromagnetic welded materials. In this paper, the variations of the normal component of the RMF, Hp(y), perpendicular to welded seam are measured. The finite element method is used to model residual stress in the specimen. The influence of residual stress on the Hp(y) component is shown. It is found that the distributions of the Hp(y) component are described by a Boltzmann fitting curve, show a good qualitative correlation with residual stress. A quantitative method for the evaluation of residual stress in ferromagnetic steels based on the gradient of the Hp(y) component and equivalent (vonMises) stress is presented.

Abstract: An experimental program was carried out by the author to investigate the shear behavior of concrete beams reinforced with continuous FRP rectangular spirals, the main variables considered in the test were the shear reinforcement ratio and the shear span to depth ratio and the longitudinal reinforcement ratio. However, the experimental program is inadequate to gain insight into the shear behavior of the members. First, the quantities of test specimens were too small, only six beams were made and tested, the experimental database was so limited that the resultant analytical results and conclusions may not be sound enough. Second, not all the main factors that have influences on the shear behavior of the members have been treated as variables in the experimental program, such as the effective transverse compression stress and the concrete compression strength, the influences of these two factor on the shear behavior of the members were not clear yet through the experimental study. Considering the insufficient information provided by the experimental investigation, the parametric analysis of the shear behavior of the members was carried out, and a revised rotating-angle softened truss model for the shear analysis of the members was proposed as the analytical tool. Based on the proposed model, the influences of various factors on the shear capacity and shear failure modes of the members were discussed, related nonlinear analysis was carried out using the arithmetic of iteration and step approximation, and several FORTRAN codes were written accordingly. Through the experimental study and the parametric analysis, it is indicated that the shear capacity and the shear failure modes of the members are greatly influenced by three major factors, including the shear reinforcement ratio and the shear span to depth ratio and the effective transverse compression stress. The influences of the concrete compression strength and the longitudinal reinforcement ratio on the shear capacity are not noticeable comparatively. The shear capacity is little affected by the shear span to depth ratio in the case of the shear-tension failure, there is no noticeable correlation between longitudinal reinforcement ratio and the shear failure modes.

Abstract: This paper proposes a practical evaluation approach to form deviation for surface of revolution based on discrete point coordinate data. An approximate curve composed of circular arc segments decided from an optimal interpolation process is accepted for computing the form deviation at measured points instead of the generating line of the surface to be inspected. This operation significantly simplifies the algorithm and improves the efficiency in the evaluation calculation. At the same time, it is also guaranteed that the difference of both form deviation values relative to the approximate surface or to the original surface is restricted within the specified accuracy in the circular arc interpolation operation. The effectiveness and efficiency of the approach are verified through a practical example of the surface of revolution with a generating line in the form of cubic Bézier curve.

Abstract: Considering an isotropic rheological law of the sheet material and the power law relationship between the stress and the plastic strain, the present paper by using the finite element method analyzes the influence of the material parameters on the results of the Erichsen test in terms of force-displacement curve of the punch and the normalized thickness measured at the specimen apex also varying the coefficient of the Coulomb friction law. Moreover for an AA5083 aluminum alloy the results of the numerical simulation of the Erichsen test will be compared to those obtained experimentally.

Abstract: In view of the questions that heavy oil has badly flow condition and lifting efficient, and considering low carbon, energy conservation and environment as goal, an advanced artificial lift technology of cyclic nature gas heat insulation and geothermal temperature heating is developed, and the temperature calculation model of the technology was founded. The analysis that different cyclic nature gas volume, cyclic depth and oil production affect the formation produced fluid temperature distribution was made. The result is that the formation produced fluid temperature increases with the addition of cyclic depth and the function of rising temperature decreases from cyclic depth to wellhead, and that the formation produced fluid temperature increases with the addition of oil production and cyclic nature gas volume. A certain well as example, using the technology, the formation produced fluid temperature increases 11.14°C, compared to the conventional artificial lift technology. And it is favorable for surface transportation.

Abstract: For the electrothermal de-icing system of an aircraft tailplane, firstly, an unsteady numerical simulation was conducted for understanding of the heating of the skin. Then ground tests in dry air conditions for the electrothermal de-icing system were designed and conducted, where the ambient temperatures were under the freezing point. The results of theoretical calculation show that, under the given conditions, the highest surface temperature of the tailplane electrothermal de-icing system can reach 67°Cand the lowest surface temperature is close to the ambient temperature. Starting from the third heating cycle, the fluctuation of the surface temperature reaches a stationary cycle. The ground tests show that the designed electrothermal de-icing system can meet the design requirements. It takes less than 25 seconds to raise the surface temperature from -20°C to 0°C. The peak surface temperature in the periodical heating cycles is below 80°C, which is lower than the tolerance limit of the skin material.

Abstract: Induction heating furnace temperature control is a complex nonlinear hysteretic inertial process, it's difficult to obtain an accurate mathematical model because the temperature and disturb from outside is complicated. The normal PID control algorithm is hard to satisfy the standards of control. The fuzzy PID controller provided in this article is a combination between fuzzy control and the traditional PID control. The Fuzzy control theory is used to setting the ratio, the integral and the differential coefficient of the PID control. In the run-up stage, rapidity is guaranteed, overstrike and the steady-state error is up to the mustard. An example indicates that fuzzy PID control is superior to the normal PID controller.

Abstract: Thermal design and thermal analysis of control cabinet for pattern sewing machine was researched to make components’ temperature meets the requirement. Basic flow sheet of research process was introduced. Then, preliminary thermal design and thermal analysis was performed, and the computed result indicated that temperature of some components was out of limit. Next, by optimizing the location of fan and components in cabinet, the temperature of servo driver 1 to 3 dropped 11.1 oC, 10.8 oC and 11.3 oC respectively. The data shows that cabinet’s heat dissipation is improved, and the thermal design of the cabinet is reasonable. Finally, Thermal test of the prototype was performed, which proves the thermal design is effective, and the numerical simulation result is correct.

Abstract: This paper is concerned with prediction of heat dissipation effect by establishing a 3d geometric model of the radiator group for a ribbon-tubular radiator of a mining dump-truck. By using the CFD approach the airflow characteristics of the radiator group are numerically calculated, and the resistance characteristic and heat transfer performance are analyzed thus the matching point of the fan is calculated, and the heat transfer performance of the water-side is simulated. Then, according to the relative heat transfer theory, the inlet and outlet water temperature of the radiator group under idling condition is obtained by analytical method. The experiment is done subsequently. The maximum deviation rate between the results of the simulation and the experiment is 6.4%, which can meet the engineering requirement and well predicts the heat dissipate performance of the radiator group. The result indicates that by combining the CFD numerical simulation with the analytical method the heat dissipation of the radiator group can be predicted effectively.