基于宽容分层序列法的飞机装配公差稳健设计技术

飞机制造中由于工序能力指数和公差等设计变量存在变差,可能导致无法满足飞机装配质量要求以及制造成本波动较大的问题。运用稳健设计方法建立了飞机装配公差的可行稳健性和敏感稳健性两类设计模型。可行稳健设计考虑了公差等设计变量对装配可行性的影响，使其变差不影响装配功能的实现;敏感稳健性设计则考虑了公差等设计变量对制造成本和装配质量的影响，在目标成本较小的前提下使得目标成本和装配质量受设计变量变差的影响最小。提出了针对飞机装配公差可行敏感稳健设计的多目标优化问题的宽容分层序列求解算法。将公差设计中制造成本、装配质量波动、制造成本波动多个设计目标按照重要性依次排序。首先求解成本最小情况下的公差一般优化解，然后在成本最小值的宽容约束下，求得具有装配质量波动最小值的公差，最后在上述两个优化目标的宽容约束下，求得成本波动最小的最优公差。应用实例和分析结果表明了方法的有效性。  

Robust Tolerancing for Aircraft Assembly Based on Tolerant Lexicographic Method

Attributing to variations of process capability index and tolerance in aircraft manufacturing,such cases will occur that the assembly quality specifications were violated or the manufacturing cost fluctuated  a lot.So,a novel tolerancing methodology based on feasible and sensitive robust design was developed.On one hand,taking into account the effects  of design parameters such as tolerances on the assembly feasiblity,the feasible robust tolerancing could ensure the  achievement of the designed  assembly function in occurrence of design variations. On the other hand,the sensitive robust tolerancing took the effects of design parameters on manufacturing cost and assembly quality into consideration,which could minimize the  influence of design variations on manufacturing cost and assembly accuracy. Furthermore,a toleant lexicotraphic method was proposed to solve the multiobjective optimization problem in feasible and sensitive robust tolerancing.Such factors as manufacturing costs, fluctuations of assembly quality and fluctuations of manufacturing cost were sorted according to their effects in tolerancing.Above all,the general tolerance with minimized manufacturing cost could be achieved.Then, under the tolerant constraint of minimized cost,the tolerance was deduced by minimizing the fluctuation of assembly quality.Finally,under the tolerant constraints of cost and fluctuation of assembly quality,the optimal tolerance with minimized cost fluctuation was obtained.The proposed methodology was proved to be feasible and effective by an example.