No abstract

No abstract

In this work, the issue of uncertainty analysis of motion errors for mechanisms is studied. First, two definitions of motion errors, that is, maximum error and accumulative error, are introduced to measure the motion accuracy in a comprehensive way. Then, the method for performing an uncertainty analysis of the two errors is discussed. For the maximum error, an analysis of the failure probability and the corresponding sensitivity analysis are carried out. For the accumulative error, the variance-based sensitivity is studied to quantify the contributions of input variables to the mechanism performance. A Kriging-based method is proposed to reduce the computational cost of the uncertainty analysis of motion errors. Finally, four examples including the classical four-bar mechanism and the landing gear mechanism for aeronautical purposes are studied with the proposed method. Discussions on the results show that the uncertainty analysis of motion errors can provide helpful information for mechanisms.

For a certain type of aircraft landing gear retraction-extension mechanism, a multi-body dynamic simulation model is established, and the time-dependent curves of force and angle are obtained. Considering the random uncertainty of friction coefficient, assembly error, and the change of hinge wear under different retraction times, the reliability model is built including three failure modes of landing gear, i.e. blocking failure, positioning failure and accuracy failure. Based on the adaptive Kriging model, the reliability and sensitivity of retraction-extension system under the condition of single failure mode and multiple failure modes in series are analyzed, and the rule of reliability and sensitivity changing with the number of operations is given. The results show that the system failure probability of landing gear mechanism tends to decrease first and then increase when considering the given information of random factors, and the influences of random factors on the failure probability vary with the number of operations. This work provides a viable tool for the reliability analysis and design of landing gear mechanisms.