Applied Mechanics and Materials Vol. 160

Abstract: An intelligent obstacle recognition method based on improved particle swarm optimization wavelet neural network (IPSO-WNN) for deicing robot on voltage transmission line is presented because traditional obstacle recognition methods often have errors due to structural constraints. Firstly, the improved PSO algorithm is proposed by introduce idea of probabilistic leap in simulated annealing. Secondly , the improved algorithm is used to optimize the parameters of the wavelet network. Finally, the trained IPSO-WNN is used to recognize and classify the wavelet moments of the obstacle edged images of robot. Experimental results show that compared with PSO-WNN this method have quicker convergence rate and higher classification precision and improve obviously recognition function of obstacle on transmission line.

Abstract: A model of gear contact has been established based on Hertz theory. Local coordinates are constructed on different meshing points because curvature of gear profile is not constant and then distributions of residual stresses and strains are given. Upper and lower bounds for the shakedown limits have been obtained. An approximate algorithm based on a stress invariant hypothesis and a stress/strain relaxation procedure is developed to solve residual stresses and strains accumulation in elastic-plastic stress analysis of gear contact. The steady-state residual stresses of gear under repeat meshing are calculated. The results are useful information for the strength design of gear.

Abstract: Based on the vibration problem of the plane gate in the inverted siphon exit of a large-scale hydraulic project in northern Xinjiang, the software ANSYS is used to build the entity model and finite element model. Considering the influence of fluid-solid coupling, the self-vibration characteristics of the gate in the water and without water are analyzed. The first six self-vibration frequencies and vibration modes of the gate are calculated. The results show that the height of water has a significant impact on the self-vibration frequencies of the plane gate. The first order natural frequency on the condition of small opening is decreased by 28.5%. It shows that the structure of the plane gate must be improved.

Abstract: For the structure failure of pressurized cylindrical shell under laser irradiation, studied with axial semi-elliptical surface crack of cylindrical shell under the combined action of laser radiation and pressure, analysis of its thermal force coupling of stress and material for the 30CrMnSiA steel. According to of static fracture toughness and based on theof estimated impact dynamic fracture toughness, the application of finite element method to study the fracture problem under dynamic load. Analyzing the crack initiation propagation and static dynamic initiation based on fracture criterion and dynamic fracture criterion for crack initiation propagation, provides a useful research of the analysis to a certain extent on the structure in thermal force coupling failure mechanism.

Abstract: Kick-up phenomenon during looping is an important factor in thermosonic wire bonding. In this study, the loping process during wire bonding was recorded by using high-speed camera, and wire profiles evolution was obtained from images sequence by image processing method. With a polynomial fitting, the wire loop profiling was described by the curvature changing, and kick-up phenomenon on gold wire was found between the instant of 290th frame(0.0537s) to 380th frame (0.0703s), the change of curvature is divided into three phases, a looping phase, a mutation phase and a kick-up phase. While in the kick-up phase, the kick up phenomenon is the most obvious. These experimental results were useful for in-depth study of kick-up phenomenon by simulation.

Abstract: The development of green cutting technology could brought higher finished quality and lower energy consumption. Therefore, the research of green cutting technology has received much attention from researchers. According to constitution of cutting process, green cutting technology is divided into dry cutting technology, trace lubrication cutting technology, low temperature cold wind cutting technology and gas jet cutting technology. The author summarized the typical characteristics of four main cutting technologies and respectively discussed them. Finally, the author has given a detailed demonstration of the application of green cutting technology.

Abstract: In order to grasp the seismic performance of the concrete perforated brick masonry building, nonlinear dynamic analysis is used for seismic response analysis of multi-storey building. In the degradation of trainer restoring force model,it is proposed that the yield moment of the inflection point is calculated by linear interpolation, the unloading time of inflection point is calculated by the precise non-iterative, which approach to improve the accuracy and efficiency of nonlinear analysis. Example shows: concrete perforated brick masonry structure in the 7-degree multi-zone can be widely used.

Abstract: It is usually difficult to integrate all operation units of complicated biochemical analysis systems into a micro-fluidic substrate. A multi substrate micro-fluidic system (MSMS) is a good option, in which operation units can be integrated into two or more substrates. Thus, it is necessary to transport droplets between two substrates. In this paper, a new method for transporting droplets between two substrates has been proposed based on surface acoustic wave (SAW). It is composed of a 128°YX-LiNbO₃ piezoelectric substrate (substrate 1) and an arc-shaped polymer. The arc-shaped polymer is seamlessly adhered to the piezoelectric substrate, and the lowest end is above another a substrate (substrate 2) with some distances. After a droplet in the substrate 1 is propelled to the arc-shaped polymer by SAW, it will slide off the polymer due to its gravity, and transported onto the substrate 2. Theoretical formulas of forces acted on the droplet have been deduced and the condition of the droplet sliding off the arc-shaped has also been obtained. Red dye solution droplets were used in the transporting experiments. Results show that the transportation of droplets is decided on curvature radius and hydrophobic property of the arc-shaped polymer and the droplet volumes. As applications, mixture operations have been implemented in substrate 2 after droplets have been transported from the substrate 1.

Abstract: In order to improve the limits of wall thickness reduction of 30CrMnSiA steel in process of spinning, realize multi-pass continuous spinning process, and furthermore improve the forming efficiency and shape accuracy of thin-walled shell of 30CrMnSiA steel in spinning process, the influence of traditional annealing and austenization plus spheroidal annealing on the structure performance of 30CrMnSiA steel and the spun performance of 30CrMnSiA steel are studied. Process parameters of traditional anneal and austenize plus spheroidal annealing are optimized to obtain higher plastic performance and lower ratio of yield strength to tensile strength. Spinning experiments of the workpieces that have been heattreated by the optimized traditional annealing process and austenization plus spheroidal process are completed. The result shows that the optimized austenization plus spheroidal annealing is beneficial to achieve a large thinning rate for flow spinning process, and can meet the demands of low cost and high efficiency of batch production.

Abstract: In order to solve optimal placement of bridge sensors based on the modal information, a multi-objective integer programming expected value model is established and the number of modal is considered as a stochastic variable in this paper, and here Fisher and MAC matrix are combined as the objective functions . Since DNA Genetic algorithm has the merits of plentiful coding, and decoding, conveying complex knowledge flexibly, these merits and the technique of stochastic simulation are also combined, which for estimating stochastic integer programming expected value models problem. And finally the feasibility of the algorithm is showed by XuGe Bridge as an example.