Life Estimation Of The Linear Vibration System

Aerospace,engineering equipment,automobile,mining machinery,such as characteristics of equipment support all aspects of the economic and social development in our country.The fatigue damage directly determine the use of these devices and efficiency,so the life estimation has always been an important part of the mechanical design.In terms of common fatigue life prediction,we generally simplify the actual mechanical system by ignoring the actual working conditions of random factors.In order to get closer to the actual results,the paper take the linear mechanical system of random parameters as the object and carry out the fatigue damage research for vibration induced:(1)In the problem of the fatigue damage induced by the forced vibration of the linear mechanical system under arbitrary loads is determined,then use shape function method according to the response of unit nodes to solving the response of the system at any position a nominal stress for solving system,using the rain flow count method after using the Goodman criterion considering the effect of mean stress to statistics stress cycle process,according to S-N fatigue life curve of materials by each stress fatigue cumulative,after all final fatigue life can be got.(2)According to the random vibration fatigue failure problem for random parametric linear mechanical systems,Newmark nunerical method combined with random perturbation method is used to solve the expectation and variance of the system vibration response and the derivation of shape function of stress and its time derivative characteristics,using the theory of random process through rate method all cyclic stress fatigue damage is derived,and the total fatigue damage cumulative finally,get the system total fatigue life.(3)For mechanical systems with degradation process of using the system,using Gamma process theory describes a linear system stiffness degradation process,select the Gamma process parameters,using Monte Carlo simulation method to verify this amount of degradation the randomness of the same system of other parameters,the discrete calctulation,to calculate the optimal discrete form for many times,to solve the stress of the dangerous point change over time,discrete time period used according to the cross rate is derived to solve damage values obtained by the method of fatigue damage,the final cumulative fatigue damage is the total fatigue life of the system.By solving life estimation of the linear vibration system with a variety of random,the analysis is more relevant in solving the engineering practical problems.we can get effective filling accurate and stable step and method of predicting the fatigue life,also provides a further potential applications in the related field.