Applied Mechanics and Materials Vol. 620

Abstract: Outer hair cells (OHCs) have a unique ability to contract and elongate in response to changes in intracellular potential, and Prestin is the motor protein of the cochlea of the OHCs. It is the first time to invest the Prestin expression in different bat species. To invest Prestin expression in different bat species, which have different frequency, we did the coronal sections’ staining of the cochlea using immunhistochemistry. Experiment was designed to determine if the high-frequency bats’ OHCs have more expression than the low-frequency bats’OHCs. We found that the expression in three species was similar and had no obvious difference. Though the study of bats Prestin evolution suggested that Prestin has accelerating evolution in echolocation bats with high frequency, our we showed that the Prestin expression has nothing to do with the frequency, and the Prestin expression in high-frequency bats and low-frequency bats is similar.

Abstract: The experimental study of unload on temperature characteristics is put up for heavy vehicle hydraulic retarder, forms the retarder unload testing method of temperature characteristics, confirms the relationship between the temperature of hydraulic retarder inner cavity and unload torquecavity air density, which can be used to instruct the simulation of retarder inside flow field in unload condition and actualize method to reduce air losing, and it lays the foundation for developing mechanism research to reduce air losing of retarder.

Abstract: This paper takes spiral bevel gear installation planes of a main reducer in a rear axle of a certain car as the research object, using ug to establish three-dimensional model of the main reducer assembly, applies adams simulation and the quantitative and qualitative method to analyze the effect law of the spiral bevel gear installation flatness error on gear mesh vibration, obtains the reasonable area of gear installation flatness error , it provides the reference for parameter design and installation of the spiral bevel gear in the main reducer.

Abstract: To determine modulus of elasticity (MOE) of the whole full-sized medium density fiberboard (MDF) by using vibration method in the future, this paper studies MDF vibration characteristics. To solve modal parameters of full-sized MDF in the condition of free vibration, the writers conducted calculation modal analysis and experimental modal analysis of the full-sized MDF with three different thicknesses respectively, compared and analyzed the first three order modal shapes and frequencies. It is found that the full-sized MDF with three different thicknesses showed the same vibration modal forms: the first and second vibration modes had bending vibration along the length direction, while the third one had bending vibration along the width direction; the frequency obtained through calculation modal analysis and experimental modal analysis had a certain difference—the first calculation modal frequency was slightly lower than the first experimental modal frequency, and the second and third calculation modal frequencies higher than the corresponding experimental modal frequencies. However, there is a good correlation between calculation modal frequency and test experimental modal frequency with the determination coefficient reaching 0.9816.

Abstract: According to the analysis to the motion track of the subsoiler, the influence on the motion track caused by the vibration amplitude and vibratory frequency has been reached, the system model of the vibratory subsoiler with slowly varying parameters of the soil has been built , the asymptotic method is adopted to carry out solving and analyzing, and experimental study is done by using the vibratory subsoiler. Analysis shows that the change of soil stiffness, soil damping, and soil quality parameters makes the system resonance curve shift, and the change of vibration amplitude, vibration frequency can improve the efficiency of deep scarification of soil.

Abstract: Piston ring lubrication in some types of low-speed 2-stroke marine diesel engines is completely different from those in medium-or high-speed diesel engines since the inner surface of cylinder liners are textured with circular grooves in macro-scale and honing texture in micro-scale. In this paper, a numerical model has been developed to study the potential of use of cylinder bore surface texturing, in the form of circumferential oil grooves with different dimensions and densities, and their efficiency to improve the tribological properties of piston ring-cylinder liner tribo-system. The average Reynolds equation has been employed in the area of micro-scale texture and the effect of macro-scale grooves has been incorporated to improve the currently lubrication model. The results showed that the cylinder liner oil grooves can efficiently be used to maintain hydrodynamic effect. It is also shown that optimum surface texturing may substantially reduce the friction losses between piston ring and cylinder liner.

Abstract: The purpose of this investigation is to research and develop a new type water turbine, which is appropriate for low-head open channel, in order to effectively utilize the unexploited hydropower energy of small river or agricultural waterway. The application of placing cross-flow runner into open channel as an undershot water turbine has been under consideration. As a result, a significant simplification was realized by removing the casings. However, flow field in the undershot cross-flow water turbine are complex movements with free surface. This means that the water depth around the runner changes with the variation in the rotation speed, and the flow field itself is complex and changing with time. Thus it is necessary to make clear the flow field around the water turbine with free surface, in order to improve the performance of this type turbine. In this research, the performance of the developed water turbine was determined and the flow field was visualized using particle image velocimetry (PIV) technique. The experimental results show that, the water depth between the outer and inner circumferences of the runner decreases as the rotation speed increases. In addition, the fixed-point velocities with different angles at the inlet and outlet regions of the first and second stages were extracted.

Abstract: This article uses the finite element analysis of a specific project. The effects of the double combination box girder segment of the negative moment area structure stress properties. Draw concrete thickness and its relationship to share the role. Another explores the impact of the thickness of the concrete box girder stability, in order to provide a reference point for future design work.

Abstract: This paper studies the Jeffcott cracked rotor based on level set, considering the oil film oscillation effects on crack rotor, building the stiffness matrix of the cracked rotor in the fixed coordinate system and the moving coordinate, deriving the nonlinear differential equations of coupled vibration of a cracked rotor, and analysis of its dynamic characteristic combined with case. Analysis shows that: crack rotor can produce nonlinear vibration in the crack and Oil film oscillation can be coupled bending and torsional vibration of cracked rotor. The analysis results provides practical basis for diagnosing Resonance of the rotor system fault and the safe operation of rotor.

Abstract: The capacitive micromachined ultrasonic transducers with square and rectangular membranes were modeled for FEM simulation. The membrane is modeled as a thin plate clamped on all sides. Resonant frequencies and vibration modal analysis were carried out. The modes of CMUT with square and rectangular membranes are different. It can be basis for building CMUTs’ structure. Moreover, the resonant frequencies will vary with different side length and ratio of length/width of membrane.