Advanced Materials Research Vols. 118-120

Abstract: The electric contact is one of the most primary elements to affect the reliability of the electric systems. Gold finish can maintain high contact reliability but increase the manufacture cost. In this paper, the effects of one sided gold plated contacts with various thickness of gold finish on the contact reliability were investigated. The failure mechanism of the one sided gold plated contacts under fretting conditions was analyzed. The contact life and the optimum thickness of the one sided gold finish under fretting conditions was achieved and compared. The effect of the curvature of the probes on the contact life was also discussed.

Abstract: Residual strength degradation of 35CrMo alloy steel is investigated experimentally and theoretically in this paper. The experimental results were obtained by high-frequency fatigue testing machine and electro-hydraulic servo testing machine at room temperature. The experimental results showed the true tensile strength under static load and the residual strength under different cycle ratio, respectively. An exponential degradation model was proposed relating the initial strength, residual strength to the applied fatigue cycles and the constant amplitude stress. The residual strength distribution was described using three-parameter Weibull probability density function. The mathematical software MatLab was used for parameter estimation. Finally, the distribution function and failure probability density function of the residual strength was received, which was significant in fatigue reliability.

Abstract: The jib is an important component for the tower crane. The reliability of the tower crane jib has a direct impact on the safety production. In the current crane industry, the traditional allowable stress method is still the main method for designing tower crane jib. As a result, the reliability of the tower crane jib cannot be given quantitatively. In this paper, by using the probabilistic method, the reliability of a tower crane jib is worked out, and a design way based on the reliability for the tower crane jib is provided.

Abstract: Towards the safety reliability problems of the quayside container crane under earthquake excitations, the anti-seismic reliability analysis has been carried out. Because of hugeness and complexity of the structure, it is absolutely impossible to carry on seismic testing with prototype. Thus, a FEM mechanical model of quayside container crane is presented by using the ANSYS codes. Based on the modal response spectrum method and the time-history analysis theory, the load-carrying performance is investigated under earthquake excitations. The results show that neither the displacement response nor the stress response is large under the earthquake excitation in every direction, which could satisfy seismic design requirements.

Abstract: Conveyer system security and reliability are related to belt conveyor drum design level .This paper proposes a method of analyzing the belt conveyer drum fatigue life reliability based on FEM, and establishes a real-time dynamic loading model, which can reflect accurately the condition of drum actual work load. This method realize drums fatigue life reliability analysis by applying rain-flow count method for processing stress spectrum that are obtained from FEM, it combines material P-S-N curves and other performance parameters and adopts Miner ruler. By applying the method on a practical project, the results indicate that the method is correct and practical. It poses the ability of avoiding the blindness in the drum structure size design, and it has the vital significance of raising drum design level.

Abstract: The sieve box is the major working part in fluidized bed, which bears the repeating dynamic loading. It generally works in severe condition, and the strength is a problem. In this paper, the vibration of the sieve box was analyzed with finite elemental method. Firstly, a 3D model of the box was constructed by PRO/E. Then the modal analysis and harmonic response of the model were investigated using ANSYS WORKBENCH. Based on the modal analysis theory，some parts of the sieve box were structurally optimized to avoid resonance. The simulation procedure adopted in the study and the achieved results could definitely facility the fluidized bed design and improve the design efficiency.

Abstract: Working condition and structure for crane boom is quite complex. In order to ensure the safety of crane, there is a high requirement for reliability. In this paper, probabilistic finite element method is used to analyze the reliability of crane boom. Parametric finite element model of crane boom is built and uncertain parameters are obtained by analyzing characteristics of dimensions, materials, loads and constraint conditions for crane boom. Uncertain parameters like structural dimensions, material parameters and loading parameters, etc are processed discretely and reliability of crane boom is obtained by using Probabilistic Design System (PDS) of ANSYS. Meanwhile, we can get the main parameters which affect reliability of crane boom and how much their influences will be by sensitivity analysis.

Abstract: In this paper, the dynamic characteristics of high-speed hybrid thrust bearing with four-recesses are optimized for different orifice diameter and supply pressure at a given speed condition, the dynamic moment coefficients of hybrid thrust bearing are analyzed, considering the thrust collar angular misalignment case to determine the optimization of orifice diameter and supply pressure under a given speed. The results provide certain reference to the hybrid thrust bearings used in high speed precision spindle.

Abstract: According to the mechanical characteristics of a certain luffing jib tower crane structure, finite element calculation model of the whole machine considering suspended cable under complicated working conditions is built. Nonlinear large displacements static structural analysis of the crane flexible attachment in the on-linear flexible scope is conducted with software ANSYS. The influence of variational attachment parameter on crane structure and anchoring points performance and the flexible attachment rule of crane are researched. Curves of influence of distance between two layers and tower overhanging height on crane structure and anchoring points performance and the reasonable layers and distance of flexible attachment are obtained and attachment rule of flexible attachment tower crane is derived.

Abstract: This paper presents a method for tolerance design of four-bar function generating mechanisms with joint clearances using Taguchi method. Based on previous studies made by other researchers, we propose a model to quantify the effects of uncertain factors on the accuracy of four-bar function generating mechanisms. Taguchi’s approach is applied to select the optimal tolerance ranges for the design parameters of function generation mechanisms. Sensitivity maps are plotted to provide an insight to the effects of parameter errors on the performance variances of four-bar function generating mechanisms. To illustrate the efficiency of the proposed methodology, the tolerance design of a four-bar function generator with joint clearances is discussed.