Research On The Robust Equilibrium Optimization Of Dynamic Characteristics Of Complex Mechanical Structures Considering Multi-source Uncertainty

In the actual engineering design,there are various uncertain factors in the complex mechanical structure during manufacturing,measurement,assembly and loading.Only by taking full account of these uncertain factors,can we ensure that the performance of the obtained structural design scheme meets the requirements in actual service,but there are still some deficiencies in the research of the current uncertain structure optimization design that need to be further studied.Firstly,most of the current research only consider the optimization of static performance,without considering whether the dynamic characteristics of the structure meet the requirements,and it is difficult to ensure the safety and stability of the structure.;Secondly,the current methods for evaluating structural performance robustness do not take into account the differences in structural performance robustness requirements under different operating conditions,and cannot meet the need for flexible adjustment of robustness judgment criteria under different operating conditions.Thirdly,the current research usually adopts regularization factors and simple weighting to achieve the robust design of multiple performance indicators of the structure,which cannot guarantee the robust balance of the overall performance of the structure.In view of these problems,the thesis carries out he dynamic characteristics of complex mechanical structures research on the non-probabilistic robust equilibrium design,robust equilibrium design considering probability reliability constraints,and robust equilibrium design under mixed uncertain conditions,which have important significance to improve the dynamic performance of complex mechanical structures and ensure their safe and stable service.The main contents of this thesis are as follows:The first chapter summarizes the domestic and foreign research status of probabilistic optimization design of mechanical structure,non-probabilistic optimization design of mechanical structure,and hybrid optimal design of probability interval of mechanical structure.The second chapter uses interval variables describe uncertain factors,establishes robust optimization design model for dynamic characteristics of complex mechanical structures considering intervals,proposes A new concept of angular coincidence coefficient of interval to more accurately describe the relative positional relationship between the structural constraint performance index and its given limit value,introduces the coincidence sensitivity coefficient to flexibly adjust the constraint performance robustness evaluation standard according to the requirements of different working conditions in the actual project,gives the robustness measurement method of the structural performance index,and combines the two-layer nested genetic algorithm and Kriging model to realize the direct solution for the non-probabilistic robust equilibrium optimization model for the dynamic characteristics of mechanical structures.The third chapter considers uncertain factors with known probability distributions,proposes A robust equilibrium design method for dynamic characteristics of mechanical structures with probabilistic reliability constraints,proposes an iterative correction method based on binary asymptotic progression to solve the problems that may occur in the current HL-RF algorithm,gives the judgment method of the feasibility of the probability uncertainty constraint performance and the measurement method of the robustness of each constraint or target performance,calculates the overall robust equilibrium index of each dynamic characteristic index of the structure,and Combines PRSM approximate model technology,MCS method and genetic algorithm to realize the direct solution of the robust equilibrium optimization model of dynamic characteristics of mechanical structures with probability reliability constraints.The fourth chapter proposes a dynamic and robust equilibrium optimization method for mechanical structure with mixed variables with probability interval considering probability and interval variables,establishes a robust equilibrium optimization model for mechanical structure performance with interval and probability uncertain variables by decoupling interval and probability uncertainty,achieves a measure of the robustness of the constraint performance and the target performance under the influence of mixed uncertainties uncertain by combining the Kriging approximation model and the MCS method,proposes the concept of the overall robust equilibrium distance to evaluate the merits of the design vector,and achieves a robust equilibrium design of the dynamic characteristics of complex mechanical structures under mixed uncertain conditions by genetic algorithms.The fifth chapter summarizes the main work of this thesis and points out the future work to be conducted.