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声学覆盖层的低频吸声特性对潜艇声隐身性能具有重要影响.综合考虑空腔型覆盖层结构和局域共振型薄膜材料的低频吸声性能,建立局域共振型空腔覆盖层的有限元模型,研究复合结构在10 Hz~2000 Hz频段内的吸声特性,并采用局域共振理论和模态分析揭示复合结构的吸声机理,进一步得到复合结构低频吸声性能的调控规律.研究结果表明:(... 相似文献
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通过构建空腔结构理论模型,根据集中质量与薄膜之间的作用关系,得出了两个集中质量之间形成的开放型空腔结构能够使入射声波在空腔内进行散射,消耗声波能量的结论。为了获得最佳的吸声效果,采用遗传算法对空腔结构的设计参数在100~1000 Hz频域内进行优化。通过对分布在薄膜表面的集中质量进行有限元仿真分析,得出了集中质量会受声波载荷作用两两进行"拍动"的结论,拍动形式越剧烈的集中质量,其能量密度越高,在空腔结构内声波能量消耗越大。最后,通过试验验证了遗传算法对空腔结构参数设计的可行性。 相似文献
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切削参数的合理选择对数控加工的效率与质量具有重大意义。通过确定以最大生产率为目标的目标函数,引入主轴转速、进给量、切削力、机床功率及表面粗糙度等约束条件,建立切削参数优化数学模型,利用变搜索域遗传算法来优化切削参数,达到生产率最大化、成本降低和表面质量改进的目标。 相似文献
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为解决声学覆盖层在低频声学性能较差的问题,设计一种包含圆柱和圆台的组合空腔型覆盖层,利用软件COMSOL计算其在10 000 Hz以下的隔声量与吸声系数,研究覆盖层在不同结构尺寸下的声学性能,继而对组合空腔进行局部优化。结果显示:声学性能会随开孔率的增大而改善,且吸声性能曲线波峰往低频移动;当开孔率由圆台半径控制时,隔声量峰值频率往低频移动,当其由单胞半径控制时,则峰值频率往高频移动;当圆柱半径为1 mm、高度为10 mm时,声学性能相比其他尺寸空腔达到最优;对空腔中圆台结构的母线进行形状优化后,声学覆盖层声学性能得到改善。 相似文献
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Ying‐Chun Chang Long‐Jyi Yeh Min‐Chie Chiu 《International journal for numerical methods in engineering》2005,62(3):317-333
As investigated by the Occupational Safety and Health Act (OSHA) in 1970, noise is highly responsible for the psychological and physiological ills to workers. Therefore, the noise control for an enclosed system with high echo effect becomes essential. Besides, the thickness of adopted sound absorber is occasionally constrained for maintenance, the interest in minimizing the noise under space constraint is then arising. In this paper, the shape optimization of double‐layer absorber together with genetic algorithm (GA) is presented. Before optimization, one example is tested and compared with the experimental data for accuracy check of mathematical model. Thereafter, a simple optimal program in dealing with pure tone noise of 350 Hz has been pre‐run to verify the correctness of genetic algorithm before the design in full band noise being performed. Results show that both the accuracy of mathematical model and the correctness of GA method are acceptable. Consequently, this study may provide a novel scheme with GA in solving the shape optimization of sound absorber on the constrained sound absorption system. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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分析影响太阳能两级吸收式空调系统的整体性能的主要因素:集热器进出口热水的温度、各设备中溴化锂溶液的浓度与压力。根据两级吸收式循环的特点,可以运用溶液混合观点构造新型高效的太阳能吸收式制冷空调。运用仿真程序得出了太阳能两级吸收式空调在集热器出口温度在77.5℃左右时可以得到最大的整体效率,为太阳能空调系统的优化奠定了理论基础。 相似文献
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建立了汽车的统计能量分析模型,进行仿真与实验的误差分析,验证了所建模型的有效性,然后选取四层吸声材料布置于乘员舱顶棚,采用优化拉丁方法,以其厚度为设计变量,为降低驾驶员耳旁噪声和满足汽车结构轻量化和低成本的要求,以驾驶员头部声腔A声级降低幅度、吸声材料重量、降噪效率、材料价格和性价比为优化目标,选取30个样本点进行试验设计并通过计算得到全部响应值,之后建立了Kriging近似模型,为验证该近似模型模拟精度,任选三个新的样本点分析近似模型和仿真结果间的误差,最后以近似模型为基础执行多目标优化,与吸声材料初始组合相比,A声级降低幅度反而减小了0.289dB,但重量降低了54.8%,降噪效率提高了85.6%,材料价格降低了21.1%,性价比提高了6.0%。 相似文献
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针对应力变化较大的碳纤维增强复合材料层合板,提出削层结构铺层分级优化模式。通过将结构分解为若干子铺层并对各子铺层的位置、尺寸、铺层数以及铺层顺序进行优化,得到了满足强度和可制造性要求且质量最小的结构设计方案。该模式的第1、2级优化利用参考层对各子铺层位置及尺寸进行优化,第3级优化通过引入3次样条插值参数化方法对各子铺层层数和铺层顺序进行优化。参考层的引入可减少设计变量的数量,3次样条插值参数化方法可解决以铺层角为设计变量时设计变量数目不确定的问题。利用有限元方法对结构进行力学分析计算,并依据Tsai-Wu准则确定结构强度。在第2、3级优化中利用遗传算法对优化问题进行求解。算例计算表明:削层结构铺层分级优化模式结果合理可信。与均匀铺层方法结果比较可知:削层结构可有效减少结构质量。 相似文献
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Optimization problems could happen often in discrete or discontinuous search space. Therefore, the traditional gradient‐based methods are not able to apply to this kind of problems. The discrete design variables are considered reasonably and the heuristic techniques are generally adopted to solve this problem, and the genetic algorithm based on stochastic search technique is one of these. The genetic algorithm method with discrete variables can be applied to structural optimization problems, such as composite laminated structures or trusses. However, the discrete optimization adopted in genetic algorithm gives rise to a troublesome task that is a mapping between each strings and discrete variables. And also, its solution quality could be restricted in some cases. In this study, a technique using the genetic algorithm characteristics is developed to utilize continuous design variables instead of discrete design variables in discontinuous solution spaces. Additionally, the proposed algorithm, which is manipulating a fitness function artificially, is applied to example problems and its results are compared with the general discrete genetic algorithm. The example problems are to optimize support positions of an unstable structure with discontinuous solution spaces. 相似文献
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An improved genetic algorithm (IGA) is presented to solve the mixed-discrete-continuous design optimization problems. The IGA approach combines the traditional genetic algorithm with the experimental design method. The experimental design method is incorporated in the crossover operations to systematically select better genes to tailor the crossover operations in order to find the representative chromosomes to be the new potential offspring, so that the IGA approach possesses the merit of global exploration and obtains better solutions. The presented IGA approach is effectively applied to solve one structural and five mechanical engineering problems. The computational results show that the presented IGA approach can obtain better solutions than both the GA-based and the particle-swarm-optimizer-based methods reported recently. 相似文献