Applied Mechanics and Materials Vols. 55-57

Abstract: Quality characteristics of steel workpiece and their inspection methods are introduced, and the influencing factors of surface quality are analyzed by quality tools. A set of inspection scheme for cutting temperature and cutting force on-line monitoring is worked out. Thin film thermocouple technology was introduced to measure the dynamic temperature which affects the surface quality characteristics of steel workpieces. A system for measuring cutting temperature and cutting force has been developed. A high speed data acquisition card ADlink PCI-9118HG is used to acquire the temperature and force signals. Simple and friendly human-machine interface was programmed with the application of VC++ technology and Tchart controllor to achieve real-time data acquisition, display and analysis of cutting temperature and cutting force. It was concluded from the experiment that the data acquisition and measuring system is easy and flexible to use.

Abstract: By treating chitin with ultrasonic in hot concentrated NaOH solution for about 30-120min, chitosan swellable highly in alkali was prepared. The swelling behavior and the structure of the prepared chitosan were invested. It was shown that the prepared chitosan can swell highly in NaOH solution by freeze-thawing treatment, with the particles turns into hydrogel. The swelling behavior showed that with the increase of NaOH concentration, the swelling degree of chitosan increases, until a concentration of 8.0 wt%, and ultrasonic treatment time has less significant influence on the swelling behavior. SEM showed that ultrasonic treatment makes the structure of chitin enough looser for the permeation of NaOH and H₂O, resulting in the swelling of chitosan in alkali solution.

Abstract: The interference-fit riveting technique is widely used in aircraft assembly, which can generate residual stress around the wall of hole and significantly improve the fatigue life of the structure. The residual stress is usually determined by experiment or numerical simulation, locking of theoretical support. So this paper researches the residual stress modeling of the panel in a riveting process. Firstly, based on the axisymmetric upsetting theory, dividing the riveting process into two stages, the formulas for calculating the contract pressure caused by the rivet around the hole of panel are built. Secondly, under the action of contact pressure, the residual stress distribution expressions are developed by elastic-plastic mechanics. Finally, in ABAQUS system, a three-dimensional instance made up of one flush rivet and two panels of aluminum alloy is used to verify the theoretical formulas. The feasibility of the theoretical formulas about the residual stress of the panel is validated by comparing the theoretical calculation and finite element simulation results.

Abstract: The classical Sobel edge detection operator has the shortcomings of low edge positioning accuracy and coarse edge, image edge detection based on improved Sobel operator and clustering algorithm was proposed. Four Sobel-like edge operators are used to improve the edge positioning accuracy and clustering algorithm are used to edge thinning. The experimental result demonstrates that the effect of the edge detection is greatly improved comparing with the traditional edge detection methods.

Abstract: An enhanced discrete Fourier transform DFT-based channel estimation for OFDM systems is proposed. Conventional DFT-based channel estimations improve the performance by suppressing time domain noise. However, they potentially require information on channel impulse responses and may also result in mean-square error (MSE) floor due to incorrect channel information such as channel delay spread. In order to overcome the disadvantage, our proposed channel estimation can improve the performance by deciding significant channel taps adaptively. Significant channel taps are detected on the basis of Mahalanobis distance discriminant analysis. Simulation results demonstrate that the proposed algorithm outperforms the conventional DFT-based estimation in terms of BER and MSE performance.

Abstract: In Virtual Reality Interactive Systems, texture is one of the most important factors which affects the scene fidelity and the entire system resources. In this article, we talk about the texture making methods in constructing virtual reality interactive scene. We discuss the bake mapping technique, and make the comparison and analysis among different mapping methods to find the method that can get the best effect with limited resources. According to our study method, users can choose the most appropriate methods based on their needs to construct the virtual reality scenes effectively, and make more realistic effects with limited hardware and software resources.

Abstract: Internet of Things (IOT) is an important part of the new generation information technology; it has been applied successfully. As a key technology of the IOT, Radio Frequency Identification (RFID) has been promoted and applied in a number of areas, including library management. This paper introduces the IOT, and then studies the work principles and technology standards of RFID, and compared with other identification techniques; last, this article explores the application feasibility of RFID in library and pointed out its shortcomings.

Abstract: In order to study the dynamic wear of revolution joint with clearance in mechanical system, the dynamic model of mechanical system with joint clearance is presented. The clearance model is established based on clearance vector model. The contact dynamic model in joint clearance is established using the nonlinear equivalent spring-damp model and the friction effect is considered by using correction Coulomb friction model. And then the models are incorporated into dynamics simulation software ADAMS, the dynamics model of mechanical system with joint clearance is established based on ADAMS and the simulation is made. Furthermore, the contact dynamics parameters are drawn and calculate the wear volume of joint clearance based on Archard’s wear model. Finally, a crank follower mechanical system is used to perform the simulation and the dynamic wear characteristics are analyzed.

Abstract: Micro hobbing technology is an extension of traditional technology in small scale for processing micro gear. The micro gear shaft which module is 0.175mm is processed by micro hobbing technology. The tooth profile of the micro gear shaft is perfect and the tooth is divided evenly, the burr of the edge is small and the surface roughness is high enough to achieve the requirements of the micro gear shaft. In paper, the design of micro gear hob and the micro hobbing technology is the key factor to the manufacture of micro gear and is presented detailed. The result shows micro hobbing is a good way to process micro gear and it has some advantages including the high efficiency, accuracy in tooth profile, lower cost and widely range of suitable materials. micro-hobbing technology has significance value to research and can be applied in manufacturing the micro gear.

Abstract: When designing implantable biomedical MEMS devices, we must provide electric power source with long life and small size to drive the sensors and actuators work. Obviously, traditional battery is not a good choice because of its large size, limited lifetime and finite power storage. Living creatures all have non-electric energy sources, like mechanical energy from heart beat and pulse. Piezoelectric structure can convert mechanical energy to electric energy. In the same design condition, the more electric energy is generated, the better the piezoelectric structure design. This paper discusses the topology optimization method for the most efficient implantable piezoelectric energy harvesting device. Finally, a design example based on the proposed method is given and the result is discussed.