Papers by Keyword: Joint Clearance

Abstract: The paper discusses seismic performance of deployable brace member as well as its application in single-story single-bay frame by using finite element method in OpenSees Navigator. Even though deployable structure has wide applications in engineering area, it is almost blank for earthquake (seismic) engineering. A finite element deployable brace model consisting two identical struts and a revolute joint is built in this paper. The model considers joint clearance and initial eccentricity to accord practical situation. Hysteresis analysis has been done on the brace model as well as its application. The results show deployable structure provides sufficient lateral stiffness and ductility. Strut eccentricity is the key factor affecting the capacity of the strut and buckling strength, while joint clearance also has influence on the strut capacity and energy dissipation.

Abstract: Bearing cooler coils connector of 175 MW hydropower plant experienced premature leaks after one year operation and caused an unscheduled shutdown. To avoid the same failure in the future, the leaking bearing cooler coils connector was investigated. Nondestructive tests, such as chemical composition analysis, hardness test, metallographic test, characterization of the filler brazing by scanning electron microscopy – energy dispersive X-ray spectroscopy were conducted. The results confirmed that the bearing cooler coils connector consisted of two types of material namely the flange material which was made of stainless steel 304 and the pipe material which was a Cu/Ni 90/10 and were joined together using brazing process. It was a clearly evidence that leaks occurred in the brazing area and the leakage was due to improper brazing process. It was shown by the excessive gap and a lot of porosity.

Abstract: On the basis of dynamics simulation software ADAMS,using a simplified model of crank-rocker mechanism with gravitational field for the study.It built the model of contact force and the coulomb friction [1,2] to simulate the motion pair with clearance.This paper made a preliminary study on the effect of the multi-joint clearance on the dynamics characteristics of the institution.The result showed that mechanism with double joint clearance had little influence on the mechanism speed and had relatively large impact on mechanism acceleration.Mechanism with three joint clearance increased the impact on the speed and acceleration appeared greater fluctuation and changes in direction.However,the contact force with three joint clearance was more stable and smaller than mechanism with double joint clearance. This kind of model is closer to the object movement in reality, so it can predict the laws of motion and provides more reliable theoretical reference for precision、optimization and noise prevention design of institutions.

Abstract: On the basis of dynamics simulation software ADAMS, we built dynamics models of planar four-bar mechanism, it built the model of contact force and friction to analysis the dynamics simulation of mechanism. we made a preliminary study on the effect on the flexible components and the backlash of the kinematic pair on mechanical system dynamics characteristics. The result showed that mechanism with single joint clearance had little influence on the mechanism speed and had some impact on mechanism acceleration. Mechanism with multi-joint clearance had bigger effect on the mechanism and acceleration appeared noticeable fluctuation, this model was closer to the phenomenon of objects movements in reality. The simulation results provided reliable reference of mechanical design.

Abstract: In this paper, a review of developments in the dynamic characteristics of traditional and inflatable solar array is presented. Three major aspects that affect the dynamic behavior of solar array are reviewed: component flexibility, joint clearance and thermally induced vibration. Important results and methods of exploring the dynamic characteristics of inflatable solar array are discussed. Future research areas in dynamic characteristics of solar array are identified as damping mechanism of inflatable structure, the relationship between pressurization level and damping ratio, application of more advanced contact model, dynamic characteristics of solar array made of new materials and consideration of deformation in multiple dimensions.

Abstract: Inconel 718 and Waspaloy superalloy was vacuum brazed using BNi2 filler. The effect of joint clearance and brazing temperature on the interfacial microstructure, element and microhardness distribution were studied systematically. The microstructure of the brazed joints is both mainly solid solution when the brazing clearance is 30μm at 1080 °C and 100μm at 1140 °C. The results show that the elements diffusion of nickel based filler is more active with the decrease of the joint clearance and increase of brazing temperature. The peak of microhardness is shown at the centerline of brazing seam.

Abstract: The dynamic behavior of a reciprocating compressor transmission mechanism with joint clearance is studied in this paper. A transmission mechanism virtual prototype model is built under software ADAMS. Revolute joint between connecting rod and crosshead pin is modeled with clearance by contact model based on the so called Impact-function, and four processes of cylinder pressure load is simulated by the IF function. Cylinder pressure load, amplitude of joint clearance, crank speed and flexibility of connecting rod is taken as influence factors. Four different cases were simulated. Joint contact forces, accelerations of compressor block and journal centre path are used to analyze the dynamic behavior. The presented results show that these factors play a significant role of dynamic behavior of mechanisms.

Abstract: The joint clearance on mechanism dynamic characteristics influence can not be ignored. This paper established a geometrical model of planar four-bar mechanism, it built the model of contact force and friction and embedded into the software of ADAMS dynamics analysis mechanical system, which analysis the dynamics simulation of mechanism. We obtain a accurate prediction of dynamic characteristics of mechanism with joint clearance effect from the analysis. What's more the results provide reference and basis for later mechanism design [1,2,3].

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: 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.