Applied Mechanics and Materials Vol. 376

Abstract: The vibration analysis of a multi-cracked beam using discrete element technique (DET) was investigated in this study. Undamped simply supported beam was traversed by moving mass with constant speed and Euler Bernoulli beam theory was considered. Cracks are located in different positions and maximum deflection of mid-span was derived and compared. The results showed that increasing numbers of cracks in the beam causes more deflection while maximum deflection of beam takes longer time to build up. The results were validated by solving the equations generated using finite element method (FEM) and their comparison with already established results from previous similar studies (literatures) showed good agreement.

Abstract: In order to apply the concepts of k-means to deal with any specified dissimilarity measures, we propose a k-exemplars clustering method that modifies k-means by restricting the cluster centers on data points. The proposed method not only has similar clustering accuracy as k-means but also faster convergence. According to the definition of the objective function of k-exemplars, the proposed method can be used to deal with a relational data set, and the cluster centers (exemplars) of each cluster will also be extracted. Hence, the k-exemplars can work in an environment with specified dissimilarity measures.

Abstract: Nonlinear numerical analysis for the force performance of frame middle joint is processed in this paper with the finite element software of ABAQUS. Compared with experimental results, numerical analysis results are found to be reasonable. Then the influence of factors such as shaped steel ratio and axial-load ratio are contrastively analyzed. The results show that shaped steel ratio has a greater influence on the bearing capacity and hysteretic performance of the structure, but the axial-load ratio has less influence.

Abstract: We present an idea for modeling flexible ocean umbilical cable using a nonlinear finite element method. The umbilical cable is assembled by Reissners geometrically exact beam elements, which take account of the geometric nonlinearities of large rotation and displacement, and effects of axial load and bending stiffness for modeling of slack cables. The linearization and discretization of the entire weak form for the umbilical cable system are proposed. The resulting semi-discrete motion equations are solved by the Newmark method. The capability of considering the action of horizontal ocean current is a key feature of this analysis. An example about the two-dimensional dynamic behavior of the umbilical cable system in depth-dependent ocean current with sinusoidal ship motion is presented.

Abstract: Four-wheel steering (4ws) refers to the meaning of besides usually turn the front wheels of the vehicle, plus the corresponding rear wheel steering. Its main purpose is to increase the vehicle steering stability at high speed or in lateral force under the action , improve the vehicle steering portability at low speed and turning radius at high speed.A 4ws vehicle dynamic model with two-degree of freedom^[1,2] was established, and presents the corresponding dynamic equation. Using the theory of vehicle handling dynamics,according to the 4ws vehicle dynamic equation,the transient response of 4ws vehicle steering are detailed analyzed.Compared with 2ws steering, illustrates the manipulation of 4ws vehicle has strong handling stability.

Abstract: Load distribution, contact angle, rotate speed of rolling element, support stiffness of bearing, fatigue life and other aggregative indicators are got through the simulation statics analysis program of high speed ball bearing. Consequently, it is widely used in the engineering field. The domestic thesis about the simulation statics analysis program of the high speed ball bearing is barely reported, and most of the theoretical research thesis are not specific and have some mistakes. Consequently, aim for programming about a practical suit of the simulation statics analysis program of ball bearing, and the certain numerical problems are studied in the procedure of program.

Abstract: In order to improve the efficiency and practicality of trajectory planning of the mechanical arm, making the trajectory smooth and continuous, the method of B-spline curve of trajectory planning is adopted. Considering the three contraint conditions: the speed, the acceleration and the change rate of acceleration, the time interval of each curve is optimized using PSO (particle swarm optimization) algorithm. Simulation results show the PSO algorithm can reduce the time interval of each curve. This means that this method can effectively improve the operating efficiency of the mechanical arm.

Abstract: Precision manufacturing is very important in the modern industrial manufacturing. Voice coil actuator (VCA) is the actuator, which directly change the signal of electricity to movement. We devised a form of precision locating system driven directly by VCA and apply gas static pressure bracing to substitute rigid bracing by mechanical contact. PID Control is widely used to control the system, but the parameters of PID control hard to be get out. Genetic algorithm is imitate living creature environment in of a kind of orientation overall situation of the genetic, can be professional at solving complicated system or the huge problem and it acquired a success application in many industrial engineering realms and had already got extensive concern. Thus, we use genetic algorithm to find the right parameters of PID control. As a whole, in this paper we introduce the genetic algorithm, analyze the control model of precision locating System, discuss using the Genetic algorithm to find the right parameter to control the precision locating System of voice coil actuator, the simulation is give out.

Abstract: For a building under evolutionary random excitations, a new random vibration analysis based on equivalent excitation method is presented, in which, the equivalent excitation is constructed by using continuous wavelet transform. When the input power spectral density of a seismic excitation is modulated by a time varying function, the continuous wavelet coefficients are calculated firstly by using scales and the evolutionary power spectral density, then the equivalent excitation is constructed by inverse continuous wavelet transform, finally the random vibration analysis is carried out following the procedures of the equivalent excitation method. An example is given to show the whole procedure, in which the special ability of the method for dealing with the evolutionary random excitation is discussed in detail.

Abstract: This paper presents a brief introduction of BDD. Through the analysis of the question existing in BDD construction, such as a lot of useless variable nodes, repeated calculation, redundant nodes and calculation, and so on, this paper introduces axiom system and compute-table to the BDD construction and present a new method. This method eliminates the useless node, reduces redundant nodes and lots of repeated computation. It can improve the implementation efficiency and avoid wasting memory.