Applied Mechanics and Materials Vols. 34-35

Abstract: A critical speed formula was given based on the analysis of kinematic characteristics during tangential ultrasonic vibration assisted grinding (TUAG) process. By the formula, the machining parameters can be correctly set to insure the separate characteristics of TUAG process. The grinding force can be decreased and the machining surface quality can be improved during TUAG process with separability. Grinding experiments were conducted, and the experiment results are in good agreement with theory analysis results.

Abstract: The behavior and response of structural reinforced concrete elements under severe short duration dynamic loads was investigated numerically. The analytical approach utilized the Timoshenko beam theory for the analysis of reinforced concrete flexural elements, such as beams and one-way slabs. The differential equations of the Timoshenko beam theory were solved numerically by applying the finite difference method (FDM). The proposed FDM not only can account for both the shear and flexural deformations, but also can incorporate the strain rate effects on the strength of steel and concrete into the analysis. The results of this proposed FDM were compared with those obtained by using finite element method (FEM), were also compared with experimental data obtained by other investigators. The procedure of FDM in this paper was both fast-running and accurate and most suitable for design office application.

Abstract: A series of experiment were performed to test the tribological properties of Si3N4 ceramic pair lubricated by emulsions of alcohol, acid and alkane. The experiment results showed that the function group can’t improve ceramic lubrication, which is reverse to metals. Under the condition of same carbon-chain, the lubrication by alkane is better than alcohol and acid. With the friction curve and wear scar diameter analysis, the paper studied the tribological properties of alcohol interfacial film. On the basis of above, hydrophilcity was involved to find the lubricating mechanism of emulsions.

Abstract: This paper studied the time-domain waveform characteristics of diesel engine cylinder head vibration. The relative relationship between the various explosions of diesel engine were analyzed and compared. Seven criteria were proposed under which to achieve the time domain waveform peak identification in the absence of TDC signal. According to the criteria computer algorithms for the time domain waveform peak identification were given. The method can reduce the vibration diagnosis system using request such as can achieve misfire fault diagnosis in the absence of TDC signal.

Abstract: This paper studied misfire diagnosis of diesel engine based on short-time vibration characters. Misfire of diesel engine was simulated by the vibration monitoring test. Cylinder vibration signal and top center signal were collected under different states. The short-time vibration signal of each cylinder was intercepted according to the diesel combustion sequence, effective value was calculated, and BP Neural Network model built with this character was used to diagnose diesel misfire. The result shows that this method can locate the misfire cylinder effectively, and it is meaningful for guiding the detection and repair of vehicles.

Abstract: It is easy to have deformation that non-rigid materials is on high-speed processing, so this paper introduces the fuzzy neural networks combine with computer vision measurement technology to control this process. Based on the traditional PID control, increasing a fuzzy neural network predictor for pre-processing of trajectory compensation. Established a fuzzy neural network deformation prediction model of the single needle quilting, and simulated. Experimental and simulation results show that: error compensation which based on fuzzy neural network, have a good real-time, allow fast and accurate automated processing of quilting.

Abstract: This paper presents the way of how to reduce the torque and flux linkage ripples, and having better dynamic and static state performance. A new type of neural network resistance observer is developed, on basis of BP neural network, to measure the real time stator resistance of induction motor. Another improved method using fuzzy and adaptive principle can track the change of torque by regulating the duty ratio of the voltage space vector.

Abstract: The main function of turning linkage of automobile is to realize the ideal relations of turn angle of the internal and external wheels when vehicles steering. At present the main methods on design computing and verifying turning linkage have still been the planar graphing and analysis method, therefore it is very important to adopt optimization methods to design the steering linkage. Being satisfied with the Ackerman theory steering characteristics and boundary constraints, considering the ideal relationship of steering angles between external and internal wheels in steering linkage to ensure motion accuracy of automobile, optimization model of turning linkage is established. Then the objective function with penalty terms is built by penalty strategy with addition type, so the constrained optimization is transformed into the unconstrained optimization. The simulated annealing algorithm is adopted to optimize turning linkage of automobile, so that optimization process was simplified and the global optimal solution is ensured reliably.

Abstract: Laser ultrasound technology has many advantages such as being non-contact, nondestructive, fast, accurate and low cost. Therefore it is usually used as an effective way to detect and characterize small surface or subsurface breaking cracks. The optical fiber F-P sensor is adapted to laser ultrasound detection field because it can detect ultrasound signals non-contact. But the optical fiber F-P sensor deviates from working point easily because of machining error and external factors in practical applications. It leads to output signal attenuation and the decreasing of signal noise ratio. On this problem, an optical fiber F-P sensing system based on two wavelength quadrature-shifted demodulation technique is designed. The mathematical model of sensing system is established. Differential Evolution Algorithm is introduced to establish the optimal model of sensing system for the first time. The structure of sensing system is optimized designed. The non-contact laser ultrasound experimental devices based on optical fiber F-P senor are established for detecting surface defects. The experimental results show this sensor can detect surface defects effectively. It has higher sensitivity and larger signal-to-noise ratio.

Abstract: Making full use of fly ash (FA) is an important part of sustainable materials development in the word. This paper discussed the carbonation resistance of concrete with 10%, 20% and 25% fly ash replacement ratios(FA%). The process was accelerated in artificial carbonation laboratory by controlling 20% concentration of CO2, 10°C~30°C temperature and 50%~70% relative humidity(RH). The depth of carbonation could be observed by spraying phenolphthalein solution on the fresh broken concrete surface. The test results show that adding fly ash into concrete results in the decrease of cement consumption and calcium hydroxide, so carbonation rate increases. But with the increase of FA% and carbonization time, the drop speed of carbonation rate slower, the differences in the microstructure are detailed. In addition, the carbonation rate increases when the ambient temperature varies from 10°C to 30°C and ambient RH falls from 70% to 50%. It concludes that the 10°C ambient temperature and 70% ambient RH are superior to other environmental conditions for enhanceing concrete carbonation resistance, and mixing 10%~25% FA into concrete have little influence on carbonation resistance of concrete if have adequate curing time.