Applied Mechanics and Materials Vols. 184-185

Abstract: Based upon the Reissner-Naghdi-Berry shell theory, a semi-analytical domain decomposition method is presented to analyze the forced vibration of a joined conical-cylindrical-spherical shell with general boundary conditions. The joined shell was divided into some conical, cylindrical and spherical shell segments along the axis of revolution. The constraint equations derived from interface continuity conditions between two adjacent shell segments were introduced into the energy functional of the joined shell. Displacement variables of each shell segment are expressed as a mixed double series in the forms of Fourier series in the circumferential direction and Chebyshev orthogonal polynomial in the longitudinal direction. The forced vibration response of the joined shells subjected to various harmonic excitations and boundary conditions was calculated and compared with those FEM results obtained by finite element software ANSYS to confirm the reliability and accuracy of this analytical solution.

Abstract: Taguchi optimization methodology is used to optimize Rotary Ultrasonic Machining (RUM) parameters for the milling of zirconia ceramic. The influence of the RUM parameters such as vibration frequency, vibration amplitude, spindle speed, feed rate, and depth of cut on the surface roughness is studied. A three-level orthogonal array table is used to determine the signal-to-noise (S/N) ratios based on Taguchi’s design of experiments. Furthermore, analysis of variance (ANOVA) has been performed to study the relative significance of the different factors on the surface roughness of zirconia ceramic. Finally, verification tests were carried out to compare the predicted values of the surface roughness with their experimental values in order to confirm the effectiveness of the Taguchi Optimization.

Abstract: Simulation analysis and experiment research are performed on the aeroacoustic noise of a landing gear component in this paper. Detached Eddy Simulation (DES) is used to produce the flow field of the model. The Ffowcs-Williams/Hawkings (FW-H) equation is used to calculate the acoustic field. The sound field radiated from the model is measured in the acoustic wind tunnel. A comparison shows that the simulation results agree well with the experiment results under the acoustic far field condition. The results show that the noise radiated from the model is broadband noise. The directivity of the noise source is like a type of dipole. The wheel is the largest contributor and the strut is the least contributor to the landing gear noise. The results can provide some reference for low noise landing gear design.

Abstract: Simulations analysis of the aerodynamic for a sports car modeling before and after optimization was introduced in the paper by using commercial CFD code--STAR-CCM+. In the first simulation, we got the drag coefficient, the pressure of convective and the turbulent kinetic energy spectrum，then we found the positions that may affect the drag coefficient. Further analysis inferred that our modifications accorded with the aerodynamic principles. These results can provide the basis for the modeling design and further optimization.

Abstract: A quantitative method for evaluating the casting complexity has been elaborated in the present paper. It was consisted of two aspects, one is the casting geometry structure complexity, and the other one is the casting shape-forming complexity. The casting geometry structure complex degree can be described in a quantitative form based on the basic tissues that compose the casting, the geometry structure complexity is C=-[n₁log(n₁/N)+n₂log(n₂)/N+...+n_klog(n_k/N)] . And the casting shape-forming complex degree can be estimated by the surface modulus and its distribution characteristics at x, y, z coordinates. When the casting geometry structure is complex and the shape-forming is complex, the casting can be defined as “complicated casting”.

Abstract: An object’s fine surface can change the object's surface friction property. So this paper aims to study the friction property of concave laser-textured surface through experiment. First, the Nd:YAG laser is used to generate micro-pores on Cr12 steel surface in the research and then its impact on object's surface friction property is studied. The test result shows that compared with the non-textured surfaces, the concave surface with area density of 5% and depth of I10.8 can reduce the friction coefficient significantly.

Abstract: Based on the modeling characteristic of spiral bevel gears, an accurately UG parametric model was established. The single-conditional finite element analysis method cannot satisfy the need of research under the realistic complex environment. Therefore, a thermo-mechanical model was built in the MSC.MARC Software. The contact region, contact stress, bend stress of dedendum and the change of the temperature were calculated. Some comparisons were done between these two methods. The result shows that the method was more feasible, and could provide a reliable basis for the further optimal design.

Abstract: This paper made an analysis by extracting characteristic line of key positions from the complicated and subtle surfaces of auto shell with the help of measuring tool and curve detection tool in a 3D modeling software, Rhinoceros. A research was made on the proportion of auto’s key nodes and curvature variation of characteristic line as well as its relation with optical effect on auto’s surfaces. Finally, this paper verified the feasibility for research on characteristic line of auto modeling by Rhinoceros. And it is expected to come to general rule for auto’s surface modeling through analysis of characteristic line.

Abstract: This paper made a study on automobile modeling design by taking two factors, aerodynamics and family characteristic, from many considerations, with an example of BMW 3 series. It analyzed the significant roles of these two factors’ influence on automobile modeling, and studied regular pattern of its evolution by taking a successful experience in automobile family characteristic in modeling. This paper is expected to provide assistance and instructions for automobile industry in China.