不确定理论在机械产品设计中的应用研究

发布时间：2019-02-26 11:55

【摘要】：随着我国制造业水平的不断提高,为提升机械产品竞争力的需要,产品的设计不仅要满足产品的经济性要求,产品成本尽量降低,而且必须满足机械产品稳健性和可靠性的要求,对机械产品的设计提出了新的要求。由于机械产品在设计过程中存在多种不确定性因素的影响,在未充分考虑多种不确定性因素的情况下,就会导致设计出的机械产品的稳健性和可靠度大大降低,在实际工程中,机械产品的故障率将大大增加,造成的经济损失将越来越大。因此,在机械产品设计中,为了提高机械产品的稳健性和可靠度,满足机械产品的质量要求和经济性要求,将不确定性设计优化理论引入机械产品设计中,将能满足以上要求。首先,查阅了大量关于不确定性理论在机械产品应用中的研究资料,对国内外关于不确定性理论的研究进行归纳,对不确定性理论相关概念进行归纳总结,系统研究不确定性理论中的不确定性建模方法、不确定性约束可靠性等效处理和不确定性分析方法,为解决门式起重机起升机构的不确定性设计优化研究奠定基础。其次,针对设计目标建模的特点,结合均匀试验设计的思想,提出基于均匀试验设计的二次响应面方法。该方法通过均匀试验设计减少试验次数,达到降低系统分析模型训练样本的计算成本,提高系统计算速度,加快模型收敛速度的目的。通过算例测试分析表明,上述改进近似建模方法在提高近似模型精度和加快二次响应面建模收敛方面可行有效。再次,通过对并行子空间优化过程和算法的归纳,提出基于二次响应面改进的并行子空间的不确定性优化过程,将不确定性设计优化集成于基于二次响应面的改进并行子空间不确定性优化过程中,对设计变量和系统参数进行不确定性分析,在设计优化过程中,考虑整体方案的稳健性和可靠性,实现在可接受的计算代价下获取满足稳健性和可靠性要求的最优方案,然后通过算例测试表明该方法可行有效。最后,以起重机起升机构的总体设计学科模型为基础,以基于响应面的并行子空间不确定性为方法,对起重机起升机构总体方案进行不确定性设计优化。建立起重机起升机构总体不确定性设计优化模型,根据起重机起升机构的设计要求,对起升机构的总体进行不确定性优化建模,对影响设计变量的参数进行约束设置,试验结果表明同参数下可靠度和稳健因素的并入提高了模型精度,使不确定性优化结果更符合设计要求。本文将不确定性理论应用于机械产品设计中,对提高机械产品的稳健性和可靠性,降低机械产品在实际工程应用中故障率有一定的指导意义。
[Abstract]:With the continuous improvement of the manufacturing level in China, in order to improve the competitiveness of mechanical products, the design of products should not only meet the economic requirements of the products, but also reduce the cost of the products as much as possible. Moreover, it is necessary to meet the requirements of robustness and reliability of mechanical products, and put forward new requirements for the design of mechanical products. Because of the influence of many uncertain factors in the design process of mechanical products, the robustness and reliability of the designed mechanical products will be greatly reduced under the condition of not fully considering many uncertain factors, and in the actual engineering, the stability and reliability of the designed mechanical products will be greatly reduced. The failure rate of mechanical products will increase greatly and the economic losses will be more and more serious. Therefore, in the design of mechanical products, in order to improve the robustness and reliability of mechanical products and meet the quality and economic requirements of mechanical products, the uncertainty design optimization theory will be introduced into the design of mechanical products, which will meet the above requirements. First of all, a large number of research materials about uncertainty theory in mechanical product application are reviewed, and the research on uncertainty theory at home and abroad is summarized, and the related concepts of uncertainty theory are summarized. The uncertainty modeling method in uncertainty theory and the equivalent treatment and uncertainty analysis method of uncertainty constraint reliability are systematically studied, which lays a foundation for solving the uncertainty design optimization of gantry crane lifting mechanism. Secondly, according to the characteristics of design target modeling and the idea of uniform test design, a quadratic response surface method based on uniform test design is proposed. This method reduces the number of tests by uniform test design, reduces the calculation cost of training samples of the system analysis model, improves the calculation speed of the system, and accelerates the convergence speed of the model. The results of an example show that the improved approximate modeling method is feasible and effective in improving the accuracy of the approximate model and accelerating the convergence of the quadratic response surface modeling. Thirdly, through the induction of parallel subspace optimization process and algorithm, the uncertain optimization process of parallel subspace based on quadratic response surface improvement is proposed. The uncertainty design optimization is integrated into the improved parallel subspace uncertainty optimization process based on the quadratic response surface, and the uncertainty analysis of the design variables and system parameters is carried out. In the design optimization process, the uncertainty analysis of the design variables and system parameters is carried out. Considering the robustness and reliability of the whole scheme, the optimal scheme satisfying the requirements of robustness and reliability is obtained at an acceptable computational cost. Finally, an example is given to show that the method is feasible and effective. Finally, on the basis of the general design discipline model of crane lifting mechanism and the method of parallel subspace uncertainty based on response surface, the uncertain design optimization of the overall scheme of crane lifting mechanism is carried out. The optimization model of the overall uncertainty design of the crane lifting mechanism is established. According to the design requirements of the crane lifting mechanism, the overall uncertainty optimization modeling of the lifting mechanism is carried out, and the parameters affecting the design variables are set up. The experimental results show that the combination of reliability and robustness factors under the same parameters improves the accuracy of the model and makes the uncertain optimization results more in line with the design requirements. In this paper, the application of uncertainty theory to mechanical product design has certain guiding significance for improving the robustness and reliability of mechanical products and reducing the failure rate of mechanical products in practical engineering applications.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH122

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