Zhao Xinze

Friction and Wear Characteristics of UHMWPE Studied by Orthogonal Method

UHMWPE samples were prepared by UHMWPE powder under different molding pressure in this paper. A four-factor, two-level experiment was designed to investigate the effects of different factors on the friction and wear properties of UHMWPE by pin-disc friction and wear tester. Factors include molding pressure, lubricant, sliding speed, and applied load. Friction coefficient of UHMWPE sample was found to depend significantly on load and sliding speed. Molding pressure of UHMWPE had little effects on the friction coefficient in our investigation. Weight loss of sample was decreased with the increase of sliding speed. Increasing of molding pressure, as well as decreasing normal load shows a positive effect on decrease weight loss in our investigation. Samples preformed with Bovine serum albumin (BSA) show less weight loss than that of one with distilled water. But the improvement of wear resistance is very small. SEM were used to determined the wear mechanism of UHMWPE/stainless steel pairs under different condition.

Tribology Extenics Condition Evaluation Based on Case Reasoning

Adopting matter element model to describe the tribosystem condition can integrate different types of information into a model and realize the quantity expression for the tribosystem. But the tribosystem has non-linear and random features; it means that the output parameters, such as friction coefficient, friction temperature, friction ratio etc. have steady or non-steady random features. This paper introduced case based reasoning method to evaluate the tribosystem condition based on extenics theory. Tribology condition cases index model was established based on fuzzy similar priority at first. Then through the mutual comparing with all effective elements, the fuzzy similar priority relationship between the object case and the origin case of rolling bearings were constructed; and the similar serial was obtained under the different affect factors between the object case and the origin case of rolling bearings. At last the original case was found which was most similar to the object case and the rolling bearing condition could be evaluated. The model integrated indetermination induced by each effective factor and found the original case which was the most similar to the object case from integer. Compared with the method whose index stratagem was minimal Euclid Distance, the proposal method was more reasonable.

Fault Diagnosis Method to Internal-combustion Engine Based on Integration of Scale-wavelet Power Spectrum, Rough Set and Neural Network

In order to diagnose the faults of the valve and the piston-connecting rod of internal-combustion engine (ICE), the vibration signals under normal and abnormal models were measured by experiments. Through continuous wavelet transform (CWT), the scale-wavelet power spectrum (SWPS) of signals was obtained. The wavelet power (WP) distribution on different scales of each model is observed to be similar and mainly concentrated in particular scope of 1~32. By analyzing the diversity of SWPS distribution, the WP that is most sensitive to the characteristic of each model were extracted by rough set (RS) theory as feature and taken as input to train the back-propagation neural network (BPNN). By the trained BPNN to diagnose the fault signals under detection, the correctness rate is 100%. The fault diagnosis method based on the integration of the SPWS, RS and neural network demonstrates to be efficient and feasible. It has preferable engineering applicability and referenced value to diagnosis for complex machines.

Vibroacoustic Optimization of Two Cross Stamped Ribs in a Plate

The Noise, Vibration, Harshness (NVH) behavior is one of the predominant factors for market acceptance of vehicles. As to thin parts in the automobiles, the effect result of rib stiffening can significantly alter noise and vibration character of the plate. In this paper, the location and the dimensions of two cross stamped ribs in a plate have been optimized to minimize the radiated noise power under broad-band excitation. The objective of the study is to determine effective design methods for vibroacoustic optimization of the ribs in a plate. The reconstruction of the finite element model and the boundary model in the optimization iterations is one of key factors. Radiated sound power is calculated using a boundary element method, with a finite element solver ANSYS for the solution of the structural vibration.