Research On The Life Time Performance Simulation Of The Front Linkage Of An Excavator

The life time performance of a digital system is an engineering discipline focused on predicting the time at which a system or a component will no longer perform its intended function with certainty as well as its performance.It required that deliverables as dynamic models and the models for the performance degradation for a digital system throughout its life time,whether these performance degradation models are specializing in different areas of study,must be integrated.The requirement accelerates the studying on domain-specified models and their application.This paper presents a digital mockup throughout its life time of the front structure of an excavator which includes a base dynamic model of 4 degrees of freedom of links,a model of a hydraulic actuator of its performance degradation induced by leakage and a model of the vector of the intervening space between the pin shaft and the pin hole at the root of the boom.This model can be used for predicting the performance degradation when wear occurs.The contribution of this paper can be summarized as follow:Firstly,based on Newton-Euler iteration method,the dynamic model of 4 degrees of freedom of links is built.The Coriolis,Centrifugal and couple of forces Effects are introduced as additional effects which derive from the acceleration of the non-inertial frame.And all relevant explicit formulas for this model are developed,especially the function for moment of inertia of the front structure around the vertical axis through its center of mass.The dynamic model can serve a digital system throughout its life time as a knowledge service unit.Furthermore,it can be used for understanding the laws of performance of the front structure of an excavator by extracting the different effects.Secondly,the model of the different vectors of the intervening space between the pin shaft and the pin hole at the root of the boom is developed and integrated in the digital mockup in this paper.By examining the time-motion curves at different wear stages,the effect of wear on the motion of the bucket can be predicted.Thirdly,this paper focuses on wear and its effect on performance degradation of a hydraulic actuator used for the digital mockup.The wear and fatigue in equipment applications are common fault factors that involve performance degradation.The model of a hydraulic actuator,which is developed in this paper,includes a dynamic model of a piston,a leak rate model based on percolation theory and developed contact mechanics theory,a wear model of a seal,and a model of squeezing stress and deformation of a compressed elastomeric O-ring seal.The model used for the digital mockup in this paper can be used for deducing the laws of the dynamic response of a hydraulic actuator of an excavator and for predicting the remaining useful life of a key component such as a seal.Finally,the digital mockup for predicting performance degradation is built by integrating these models developed in this paper.These models are specializing in different areas of study,so knowledge service theory is developed.Based on the obtained model,the simulation results of the time-motion curves of the bucket as main performance which are affected by the intervening space and leak are provided.