Applied Mechanics and Materials Vols. 668-669

Abstract: The amplitude feature of those current eigenfrequencies resulting from bearing banded failure is merely focused even though it is very important for distinguishing bearing failure. This theme described the torque oscillation resulting from bearing banded failure based on periodic rectangular pulse model, deduced the modulation principle between rotor magnetomotive force and torque oscillation, presented the relation expression between various banded failure and the amplitude of different eigenfrequency. Finally, a series of simulation studies were conducted and results show that the proposed theory is valid.

Abstract: The current feature for motor carried with natural mixed eccentric and bearing fault is merely focused even though it is very important for motor online diagnosis. Based on the amplitude modulation, this theme researched on periodic change of the air-gap length caused by not only bearing fault but also mixed eccentric. Based on the relationship between the motor inductance and the magnetic permeability, the inductance expression was deduced for motor with bearing fault, motor with mixed eccentric and motor with not only bearing fault but also mixed eccentric. A new current eigenfrequencies expression was introduced by employing proposed inductance expression. Finally, a series of simulation studies were conducted, the results show that the new current eigenfrequencies expression is valid and useful for online diagnosis of those motor in service.

Abstract: As new generation of low alloy high strength steel, WELDOX960 is extensively applied into heavy-duty fields including engineering machine etc. This paper adopts mixed gas protection welding to make multi-layer and multi-channel welding to low alloy high strength steel WELDOX960, using match methods with different intensities to prepare six groups of samples, respectively. The performances including joint tension and impact etc are tested for analysis after welding. The result shows that backing welding is the most important technique process in multi-layer and multi-channel welding, which has significant impact to joint performance, in the precondition that the strength is satisfied, if the material with lower strength is taken as backing layer, toughness and plasticity of the joint can be improved significantly. For example, tensile strength of sample 50-90 reaches 966.3Mpa, which is the same as 90-90, however, its toughness increases by 15%.

Abstract: In this paper we investigate the necessary condition for the existence of the periodic solution of honeycomb sandwich plate dynamic system of two-degree-of-freedom. We establish the curvilinear coordinates frame on closed orbits of the unperturbed system of the honeycomb sandwich plate dynamic system and construct successor function. Then we get the necessary condition of the existence of periodic solution by judging the existence of the successor functions. The existence of periodic solutions is important for studying the stability of sandwich plates.

Abstract: This paper studied the velocity distribution of swirling jet through employing the Fluent software to simulate the three-dimensional flow field of swirling jet. By compared the simulation results, the axial, radial, tangential velocity and non-dimensional distribution of swirling jet, and the effects of different swirl intensity on the dimensionless velocity and quantity of reflux can be obtained. Research shows the angular velocity is constant, and different swirl intensity dimensionless reflux along the axial section is similar, and so is the dimensionless velocity distribution.

Abstract: A three-dimensional model of as haft-hub of compressor impeller was set up by Pro/E. Based on the ANSYS; the finite element model was established, using the analysis method of combining submodle and paramesh. The shaft-hub of compressor impeller was simulated by virtual orthogonal design optimization method. Based on the fact that there existed radial fretting in the shaft-hub interference fit joint, researching the influence significance order and law of interference, friction coefficient and rotating speed to the maximum unit frictional work , the average friction work and the optimized parameter were obtained. It turned out that the results of the numerical simulation and orthogonal experiment were accurate and reliable, with the friction and wear effectively reduced, certain guiding references to actual assembly process were got.

Abstract: Based on the structural strength and stability theory, the paper introduce the basic principle and key considerations about the roof structural analysis, especially it should pay more attention to the concrete segment pouring effects. Taking the Tianjin LNG cryogenic storage tank as an example, which is independently finished by CNOOC, The finite element method is used for the roof strength and instability mode analysis, and study the failure sequence of strength damage and instability about the roof shell structure.

Abstract: It’s found that the rigid-body modes of brake pads and brake caliper have significant influence on squeal occurrence while analyzing disc brake squeal problems using close-loop coupling disc brake squeal model. The modal shapes of these rigid-body modes calculated from finite element method (FEM) are linear combination of multiple translational and rotational motions, which is unfavorable for further analysis. In this paper, method to achieve ‘pure’ rigid-body modes such as translations along and rotations on its principal axes of inertia is presented. Modal shapes derived from this method consist with those from FEM model under suitable constraints. The result is used in substructure modal composition analysis on a disc brake squeal problem, where the effects of specific rigid-body modes can be shown clearly. The method is helpful for researchers to choose right measures to suppress squeals.

Abstract: The interface between the surface hardened layer and the base layer would produce while the 20CrMo axis is treated with high frequency induction quenching method; therefore, the hardened case depth can be measured by high frequency ultrasonic wave based on the echo technique. The test results compared with those from the metallographic method show good qualitative agreements.

Abstract: The effects of acrylamide modified liner on bonding properties and tribological properties of self-lubricating spherical plain bearings were explored by used of Instron5944 electronic universal testing machine and homemade spherical plain bearings friction and wear tester. The results showed that the bonding properties of bearings modified by acrylamide modified liner were much more improved than those of the unmodified bearings; Self-lubricating spherical plain bearing friction and wear properties and oscillating frequency obvious correlational dependence. With the increase of the oscillation frequency, the friction coefficient and the wear loss increased, while the friction temperature rose. The friction coefficient, wear loss and friction temperature of bearings modified were much more improved than those of the unmodified bearings. It showed that the liners after modification treatment can improve the tribological properties of self-lubricating spherical plain bearings.