【作者】 杨帅；

【导师】 王太勇；

【作者基本信息】 天津大学 ， 机械制造及其自动化， 2010， 博士

【摘要】 机械产品的动态性能是其重要的性能指标,对于现代复杂、高速、重载、精密机械系统,动态性能是决定产品工作性能的重要因素。本文对以机械动力学为基础,结合机械动态设计理论及其相关的三大支撑技术(有限元技术、实验模态技术、结构优化技术)的动态性能分析优化的理论体系进行了综合分析研究。并在其基础之上开展了以下工作:针对新型大模数螺旋锥齿轮铣齿机,提出基于有限元、实验模态混合方法并结合动响应分析的动态性能分析体系。以有限元方法为基础,实验模态方法为验证,对机床结构动态性能进行了分析研究,并修正了机床结构的有限元模型。结合机床动响应分析,确定了机床的主振频率、主振振型、频谱特征。以动态性能分析理论为基础,结合优化设计方法,提出机床结构优化的三大原则。运用变量化分析方法,对立柱结构动态性能与结构形状、参数的关系进行了研究。针对实际结构进行优化改进,动态性能平均提高10%以上。以典型的悬臂结构为例,研究了固定端为弹性约束时,竖直方向刚度、旋转方向刚度以及两者共同对结构模态性能的影响。得到了前三阶“约束刚度——固有频率”的曲线和曲面图及多项式函数,经有限元验证误差小于2%。在典型的实际结构中运用以上结论,模态识别误差小于1.5%,逆向运用识别约束刚度误差平均为5%。对含分段刚度非线性振动系统,提出通过环境激励获得幅频特性曲线的方法。针对典型设备——非线性共振筛,通过实验方法分析了弹性单元的刚度及其线性部分的固有频率特性;通过环境激励的方法分析其幅频特性曲线、不同位置的振动同步性及频谱特征。为分析优化大型振动设备,建立了具有一般意义的全自由度空间弹性连接多刚体动力学系统模型。应用该模型对非线性共振筛动态性能进行研究,分析了线性部分的固有频率、不同位置的振动情况以及相应的运动轨迹,模拟出了工况下的幅频特性曲线,确定了设备的最高幅频峰值及奇数倍频率成分的产生原因,得到结果与实验一致。进而按照共振筛新的工作要求,对弹性元件的参数进行优化。更多还原

【Abstract】 Dynamic performance is a important performance characteristic of mechanical products .About modern complex ,high speed ,heavy load, precise mechanical system, dynamic performance is a important factor to determine working performance behavior .Based on mechanical dynamics ,with mechanical dynamics design theory and three supporting techniques : finite element method(FEM) technique , experiment model analysis(EMA) technique and structure optimization technique, the dynamic performance analysis and optimization theory system was researched in the paper. Based on the theory, following works had been achieved:To the new large module curved-tooth bevel gear generator, a dynamic performance analysis theory system that combined FEM, EMA and dynamic response analysis was proposed. Based on FEM, and certified by EMA, the dynamic characteristics of the machine were analyzed, and the finite element model was fixed. With the dynamic response experiment, the dominant resonance modes, the dominant resonance frequencies and the spectrum characteristics were obtained.Based on the dynamic performance analysis theory, with structure optimization method ,three primary structure optimization principles for machine tools were put forward .By variation analysis method ,to the relation of machine tool column between dynamics performance and structure shape form and parameter was researched .The actual curved-tooth bevel gear generator column were optimized ,and its dynamic performance increased 10%.For typical cantilever example, the influence of structure model characteristic by vertical constraint stiffness, rotational constraint stiffness and above two constraints stiffness in the fixed end was analyzed. The first three“constraint stiffness-nature frequency”relationship curves, surfaces and polynomial functions were obtained, and the errors of which were less than 2% by finite element method. In the actual applications, model analysis errors were less than 1.5%, and in reverse application constraint stiffness identification average errors were 5%.To the piecewise stiffness mechanical vibration system, a method of confirming amplitude——frequency characteristic by working condition excitation was proposed. To the typical equipment-the nonlinear resonance screen, the stiffness of key elastic cell and the nature frequency characteristic of linear section was tested and researched. Using the working condition excitation method, the amplitude-frequency curves, the synchronism and the frequency element of several test points were tested and analyzed.To analyzing and optimizing the large vibration equipment, a universal meaning multi-body three-dimensional space all degree of freedom dynamics model with elastic connection elements was built. Applying the dynamics model to analyze nonlinear resonance vibration screen, the nature frequency characteristic of linear section and the amplitude and movement locus on several points were analyzed, and the amplitude-frequency characteristic curves were simulated, and the maximum amplitude-frequency value and the reason of odd frequency multiplications generation were obtained , and the results of above conformed to the test results. Moreover, to the new working condition, the design parameters of the nonlinear resonance vibration screen were optimized.更多还原