机械结构相似度评价及可靠性预计研究

Research on similarity evaluation and reliability prediction of mechanical structure

在用传统的相似产品法进行可靠性预计时,所选取的相似产品与评价对象之间差异较大,会造成预计结果的偏差较大。为解决这一问题,提出了一种基于"功能—运动—动作"结构化分解的可靠性预计新方法。通过明确产品的各大运动功能建立功能层,分析完成各功能的机械部件运动建立运动层,确定实现各机械部件运动的元动作运动单元建立元动作层,建立了可靠性预计的"功能—运动—元动作运动单元"层次模型。引入区间层次分析法,确定了"功能—运动—元动作运动单元"层次模型中各子代运动单元对父代运动单元的可靠性影响权重,并构建了由子代运动单元预计父代运动单元可靠性的数学模型。确定影响评价机械结构相似度的因素,构建了区间数综合评判云模型并选取与元动作运动单元相似的参考结构,以区间数综合评价云模型得出的相似度值修正参考结构的可靠性数据来预计元动作运动单元的可靠性。将元动作运动单元的可靠性预计值代入数学模型,层层预计父代运动单元的可靠性,从而得出整个产品的可靠性水平。最后以数控转台为例进行了分析,得出了可靠性预计值,并将该方法与传统方法进行了比较。结果表明,新的可靠性预计方法具有较好的可行性和较高的准确性。

The differences between the selected similar products and evaluation object will lead to the deviation of the expected results when the reliability prediction is carried out by the traditional similar comparison method.In order to solve this problem,a new method of reliability prediction based on＂function-movement-action＂structural decomposition was proposed.A ＂function-movement-meta-action units＂hierarchical model was established for reliability prediction with steps by the means of establishing function layer by analysing the product＇s all functions,establishing movement layer by analysing components＇movements that completed corresponding functions of function layer,and establishing meta-units layer by analysing meta-actions that completed corresponding components＇movements of movement layer.The interval analytic hierarchy process（AHP）was introduced to determine the weights that reflected the influence degree of offspring motion units to parent motion units.And a mathematical model was constructed to predict parental motion units＇reliability from offspring motion units.The factors were determined that affect-ed similarity evaluation process,so as to construct interval comprehensive evaluation cloud model to evaluate similarity between meta-action units and mechanical structures,and the most similar mechanical structures were chosen as referential structures.And the similarity value was used that concluded from interval comprehensive evaluation cloud model to correct the reliability data of referential structures.Then the corrected reliability data were used to predict every meta-action units＇reliability of the meta-units layer.The reliability prediction value of the unit of motion was substituted into the mathematical model,so the parental motion units＇reliability were predicted from offspring motion units layer by layer,so as to obtain the whole product＇s reliability prediction value.At last,numerical control rotary table was taken as a case to illustrate the feasibility and accuracy by using the proposed method.The reliability prediction value was obtained and compared with the traditional method.The result shows that this new reliability prediction method has better feasibility and higher accuracy.