Applied Mechanics and Materials Vols. 184-185

Abstract: In this paper, the relation between die roll height and V-ring position of a fine blanking tool was studied by experimenting on a special part with various corner shapes. Three guide plate inserts with different V-ring positions and a die insert with constant die chamfer were machined, and a fine blanking tool was manufactured for the fine blanking experiments. Three experiments were conducted on a 650-ton fine blanking press. Each die roll height was measured and analyzed. We found the tendency of the die roll heights on the corner shapes of fine blanked parts to increase with increasing the distance between the V-ring position and the contour of the special part, and to decrease with increasing corner radius and angle. These results can be used to minimize the die roll height of fine blanking parts with corner shapes when designing the V-ring of a fine blanking tool.

Abstract: A new method called Grey Relation Modal Flexibility Curvature Difference (GRMFCD)is proposed and applied to the numerical experiment and experimental research of a substructure. The results show the ability of GMFCD to locate the inflicted damage and qualitatively evaluate its severity for single and multiple scenarios, with only a few lower order modal parameters. The effectiveness and advantages of GMFCD as compared to the flexibility indicators, such as the change in flexibility, the curvature of the flexibility difference, are demonstrated.

Abstract: Dual clutch transmission (DCT) combines the advantages of AMT and AT. This paper selects a certain type of dry DCT as the study object. The structure and working principle are introduced. A shift dynamic model is established to analyse the five phases of shift process. The oil line diagram of the electro-hydraulic control system is provided, and then the characteristics of the proportional solenoid valves which are critical control components of DCT are studied. The analysis results provide theoretical basis and guidance for the design and development for DCT.

Abstract: Reliability optimum design of the mechanical system is studied thoroughly based on the existing research results. Taking the 2K-H planetary reducer of PCP system as the physical mode, the main target of optimization is module, breadth of tooth and number of teeth. The objective function for obtaining a smaller gearbox volume is set up and the requirement of reliability is taken into account. The optimum solution is obtained by the complex method. The result is in conformity with the requirement and it indicates that the synthesis effect is satisfied. The reduction of volume is beneficial to improve PCP system performance.

Abstract: While bearing fault signals are strongly interferenced by noise, diagnosis using EMD directly for bearings fault becomes incorrect. A scheme based on Singular Value Decomposition(SVD) and Empirical Mode Decomposition(EMD) is proposed for solving this problem. Aiming at bearing fault signal characteristics, SVD preprocesses sampled signals to denoise. Then preprocessed signals are analyzed by EMD. Fault characteristic frequency can be obtained by spectrum analysis for Intrinsic Mode Functions(IMFs). This method is useful to detect fault of bearings and a comparison is made between it and EMD. The results show that this scheme can diagnose fault correctly under strong noise.

Abstract: When forming automobile semi-axle using Multi-wedges Cross-Wedge Rolling (MCWR), it is difficult to avoid the rolling bending phenomenon. Thus to improve the product quality for finding out the causes and preventing rolling bending is essential. In this paper, the finite element model(FEM) analysis software Deform-3D was used to analize the bending causes, and giving the corresponding measures from numerical simulation of the forming of multi-wedge automobile semi-axle using Cross-Wedge Rolling. Based on the corresponding simulation experiments, the results indicate that the seasures is feasible. The results of this study for rolling forming of automobile semi-axle can improve product quality and provide a theoretical basis.

Abstract: Integrated raft isolation system (IRIS) has some advantages over raft system of much smaller scale, such as higher isolation efficiency, less use of elastic couplings, etc. But the calculation of IRIS’s dynamic characteristics is complex. Finite element method usually adopted by raft designers is inefficient due to the iterative nature of design process. In this paper a six-degree-of-freedom rigid-body motion model is presented to calculate the static，quasi-static and rigid-body mode behavior of IRIS. The model is especially suitable to compare different design schemes and select out feasible ones efficiently at the initial design stage of IRIS.

Abstract: The surface roughness plays an important role in elastohydrodynamic lubrication (EHL). To improve the lubrication system the flow behavior and lubrication mechanism must be understood, especially in the thin film classification. The effects of surface roughness in the EHL problem are complicated and difficult to measure by experiment. Therefore numerical simulation using the computational fluid dynamic (CFD) approach is proposed in this research. The CFD model developed has taken the arbitrary surface roughness into consideration, and has been used to predict the characteristics of fluid flow, such as the pressure distribution, the minimal film thickness and the shear stress. The cylinder is considered to be under elastic deformation according to the theory of Hertzian contact and the surface of cylinder is defined to have an arbitrary roughness. The simulation results show that the surface roughness has significant effects on the pressure profile and shear stress, especially in the case of pure rolling, where the two parameters in the rough surface case show large fluctuations that are much higher than the corresponding smooth surface case.

Abstract: The high pressure die casting (HPDC) process of an ADC12 aluminum alloy auto part is researched by the software ProCAST and FLOW-3D, respectively. The possible HPDC defects of the auto part are analyzed. The difference of the filling process with the same technological parameter is studied. Compared with the simulation result of ProCAST, FLOW-3D software simulation result is closer to the die casting of the actual production.

Abstract: This paper studies both vibroacoustics and aeroacoustics of a centrifugal fan casing; the aim of this study is to explore a methodology to make quantitative predictions of fan casing noise. The spectra of the fan noise and casing vibration were firstly presented; discrete components related to the rotational frequency protrude in the spectra, especially the blade passing frequency (BPF). Computational fluid dynamics (CFD) technique was used to obtain the three-dimensional unsteady turbulent internal flow. Attention was paid to the pressure fluctuations on the volute wall; the shapes of pressure fluctuation were nearly sinusoidal in nature, with the BPF as the primary frequency. On the vibroacoustic side, Fast Fourier Transform (FFT) was applied to the time series of pressure fluctuations to extract the BPF component. A finite element analysis (FEA) model of the casing structure was constructed, and was validated by experimental modal analysis. The harmonic dynamic response of the casing structure was calculated with the BPF pressure fluctuation component as the excitation. The vibration results were then taken as the velocity (Neumann) boundary condition for the noise radiation model which was built in boundary element method (BEM), and the sound radiation was calculated. On the aeroacoustic side, the BPF component of pressure fluctuations was modeled as acoustic dipole source, and sound radiation was also solved by BEM. Results show that the sound pressure level (SPL) of vibroacoustics is fairly small compared to the aeroacoustic counterpart. This study shows that CFD, FEA together with BEM can be used to numerically predict BPF casing noise of turbomachinery successfully.