Advanced Materials Research Vols. 291-294

Abstract: This paper proposed an approach to fatigue reliability analysis based on the hybrid model of probability and non-probability. Due to the compatibility of measures between probability reliability models and non-probability reliability models, a hybrid model of the safety margin equation that contains random variables and interval variables in the structure system is firstly structured to analyze fatigue reliability of system by adopting the “stress-strength” theory. Then, AFOSM method and the method of interval mathematics are employed to solve the interval of the fatigue reliability index. Finally, a numerical example is given to present the application of the approach in practice.

Abstract: An efficient numerical technique, namely the Local Monte Carlo Simulation method, is presented to assess the reliability sensitivity in this paper. Firstly some samples are obtained by the random sampling, then the local domain with a constant probability content corresponding to each sample point can be defined, finally the conditional reliability and reliability sensitivity corresponding to every local region can be calculated by using linear approximation of the limit state function. The reliability and reliability sensitivity can be estimated by the expectation of all the conditional reliability and reliability sensitivity. Three examples testify the applicability, validity and accuracy of the proposed method. The results computed by the Local Monte Carlo Simulation method and the Monte Carlo method are compared, which demonstrates that, without losing precision, the computational cost by the former method is much less than the later.

Abstract: The methods of the structural reliability mainly involve analytical approximate reliability index or numerical simulation, which using the finite element solver is time-consuming and large computation. Important sampling (IS) for structural reliability analysis based on radial basis functions neural network (RBFNN) is proposed in the paper, in which trained RBFNN can model the implicit function between the structure response and input random variables. And limit state function of structure is simulated with RBFNN model applied to calculate the design point. The results show that the RBFNN can simulate the limit state functions of structures. Besides, calculation procedure based on finite element solver for structural analysis is greatly reduced and the efficiency in structural reliability evaluation is improved.

Abstract: When sequential sampling method based on MTTF is applied to weibull distribution, shape parameter is considered to be fixed. But, shape parameter in criterions or references is different from that in practice. According to sequential sampling method, with the shape parameter changing, changes of acceptance probability and rejection probability are studied. Finally, the result of simulation evaluating shows that the method of sequential sampling method is feasible and reasonable.

Abstract: The application of two representative laser surface treatments technologies which are laser shock processing technology and laser coating treatment technology are described. The application of laser shock processing in the fields of aero engine disc, wing panel formation, structural welding and strengthening, nuclear power station pressure container strengthening etc and also evaluates the effects are analyzed. The applications of laser coating treatment in the field of aeronautic manufacturing are analyzed in detail. The development direction of laser shock processing and laser coating treatment are indicated finally.

Abstract: This paper mainly studied the durability of square-section columns wrapped with CFRP by experiments. Three kinds of columns, such as columns without CFRP, columns wrapped with CFRP entirely and columns wrapped with CFRP strips, were considered. The environmental factors included dry and wet cycles of saltwater, the coupled action of freeze and thaw cycles and dry and wet cycles. The results show that the load bearing capability and the ductility of the columns wrapped with CFRP are improved greatly. The external environments have an ignoring effect on the damage model, the ductility and the stiffness of axial compressed columns, but they have an extremely effect on the load bearing capability. The load bearing capability of the columns wrapped with CFRP strips decreased more than that of the columns wrapped with CFRP entirely. And no matter how environments，the bonding between column and CFRP has no damage in this experimental study with the bonding length of 100mm.

Abstract: This paper investigates the maximum likelihood estimation of the average lifespan of products with the constraints, and the estimation of the average lifespan at stress level, which follows the exponential distribution, is derived by transforming the time-censoring step-stress accelerated life test data into the corresponding constant-stress accelerated life test data. The proposed method can overcome the shortcoming of information lose.

Abstract: The purpose of the present study is to carry out failure analysis of a scooter’s continuously variable transmission (CVT) system that is considered to be one of the key components of the scooter. In the study, several reliability analytical tools such as failure mode, effect and criticality analysis (FMECA) and fault tree analysis (FTA) are used to identify possible failure modes of the CVT system and its subsystems. The failure effects of components on the CVT system are emphasized in particular. Aside from the qualitative evaluation, simulation algorithms are developed to examine the performance of the CVT system and assess the reliability of the belt. Through the study, it is found that mechanical wear at both sides of the V-belt is the most serious problem that affects the CVT performance. The sliding collar of the driven pulley is another component that has to be observed carefully. Some design improvements are pointed out at the end of the paper.

Abstract: The first excursion failure criterion was introduced to calculate the dynamic reliability of drill string elements. Considering the random of geometry size and mechanical property parameters of drill string in deep & ultra-deep wells, the drill string system was dispersed into several basic elements according to the structure, strength and differences in the nature of formation rock in the well depth direction. And the overall dynamic reliability was quantitatively calculated through the serial theory. Through an example, the results show that the dynamic reliability of the drill string elements appeared fluctuation near the depth of 4500 meters for the inside worn of the drill string and casing, and uneven loading of drill string. The dynamic reliability of drill string in deep and complicated formation was less than any other drill strings. The drilling pressure, rotation speed and drilling depth were the main influencing factors on the dynamic reliability of drill string.

Abstract: Class_A surface reconstruction is a key part in the design of automotive body external panel. Traditional methods of Class_A surface reconstruction have some disadvantages such as low efficiency, bad flexibility and low surface quality in complicated surface reconstruction. In this paper, a method of Class_A surface reconstruction from point clouds based on NURBS patch was presented, which made surface design more flexible and direct, besides, the reconstruction efficiency and surface quality were improved.