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薄壳附加阻尼层旨在降低薄壳结构的噪声,为此本文研究该系统成本最小的优化设计:以包含阻尼的结构各层的倒厚度为设计变量,以满足设计的噪声要求为约束条件,以结构成本(包括约束阻尼层结构的薄壳基础层、阻尼层、约束层的材料费用)作为目标函数.利用K-S函数得到最大振动加速度级来描述噪声,运用响应面方法显式化噪声约束函数,采用序列二次规划求解优化模型.算例表明,增加阻尼层和约束层的厚度有利于增强结构的阻尼和刚度,优化设计使得薄壳结构的造价降低8.44%,且使结构的振动综合指标降低了27.08%,从而使结构减振降噪性能得到了提高. 相似文献
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基于响应面方法的桁架截面敏度分析和优化 总被引:2,自引:0,他引:2
把响应面方法引入桁架截面优化中,将应力和位移约束近似表达为桁架截面倒变量的线性函数。为拟合响应面,基于中心复合和单纯形试验设计方法开发了中心对称和拟单纯形试验设计两种方法,既可保证约束近似精度,又降低了结构分析计算量。对于桁架结构重量目标函数,直接推出倒变量的二阶形式,以桁架重量最小为目标的优化问题构造为标准的二次规划模型。将响应面方法计算的位移对设计变量的敏度与莫尔积分方法的近似显式进行了对比。以MSC.Patran为平台的数值算例表明:结合响应面方法,应用序列二次规划对问题进行寻优,其收敛精度及稳定性都可获得保障。 相似文献
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为了解决模型修正问题中的随机性,构建了一种基于提升小波总能量的随机模型修正方法.首先,将结 构的加速度频响函数进行提升小波变换,并提取提升小波总能量来代替加速度频响函数;然后,以待修正参数作为输入,提升小波总能量为输出构建响应面代理模型代替原来的有限元模型;接着,运用蒙特卡洛抽样抽取响应样本,并设定阈值筛选响应样本;最后,以代理模型预测得到的响应和抽样所得真实响应之间的差值最小为 目标函数,通过布谷鸟优化算法寻优求解待修正参数的均值.算例表明,所提方法修正后参数的最大误差小于3.3%,相应的频响函数曲线重合度高. 相似文献
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在薄壁圆环振动特性基础上,研究了振动环式微机械陀螺的支撑梁对环的振动模态及自然频率的影响。对一种外支撑式环形微机械陀螺敏感结构进行了ANSYS模态仿真,得到工作振动模态的变形量。以薄壁环2节点变形模态函数为参考函数对仿真变形量用最小二乘法拟合,拟合误差在4.5%以内,各函数系数一致性误差小于1.5%。基于支撑梁对环结构的模态函数影响较小的条件,用能量法和速度积分法得到结构的应变能和动能函数,进一步得到具有支撑梁环结构自然频率的近似解。选取4组支撑梁尺寸,其近似解与仿真结果的相对误差在±3%以内。 相似文献
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简单介绍了响应面方法的实质,并将其应用于二维连续体结构形状优化中,结合有限元方法,近似拟合出了状态约束(应力和位移)对设计变量的显函数,代替了复杂的解析灵敏度分析,以MSC/Patran为平台采用PCL语言开发了二维连续体形状优化的程序.文中算例通过与差分法的比较表明了这一方法的有效性和可靠性. 相似文献
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《应用力学学报》2021,(3)
通过无记忆非线性平移得到非高斯轨道高低不平顺,并以此为激励作用于列车-轨道-桥梁耦合系统结构,对比分析了高斯和非高斯轨道不平顺对列车、轨道和桥梁动力学性能的影响。结果表明:模拟的非高斯轨道不平顺相关函数和目标相关函数相互吻合;考虑四种高斯轨道不平顺激励下,车体的垂向振动加速度响应出现了紊乱现象,中国干线轨道高斯不平顺对车体的垂向振动加速度响应影响较其他3种不平顺要小,但对钢轨的垂向振动加速度响应影响比其他3种不平顺要大;美国六级轨道、德国高低干扰轨道非高斯不平顺激励下的耦合结构振动加速度响应均在不同程度上要大于其高斯轨道不平顺,但中国干线轨道不平顺对钢轨和桥梁的振动加速度响应却出现相反的影响。 相似文献
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本文主要研究了流体负载下敷设去耦阻尼层的加筋板,在外界激励力作用下的振动和声辐射,推导出了敷设去耦层有限长加筋板的振动响应和水下辐射噪声近似解析解。采用弹性理论来描述去耦层,并采用模态迭加理论构造响应函数,将加强筋等效为线力的作用,以复模量形式计及去耦阻尼层损耗因子,建立了敷设去耦阻尼层加筋板的理论解析模型,结合加筋板与去耦层变形连续条件、结构与流体连续性条件组成了声-流体-结构的耦合方程,结合数值计算方法,得到了有限长加筋板结构的振动位移及水下辐射噪声。开展相应数值算例与模型试验结果吻合较好,验证本文方法的正确性。 相似文献
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研究了3种基于时间响应函数的结构阻尼识别方法, 包括对数衰减法、希尔
伯特方法和小波方法. 给出了3种方法的实现算法, 分析了对密集模态的识别能力.
构造仿真算例, 采用3种方法识别了5{\%}, 10{\%}和30{\%}噪声条件下的模态阻尼.
结果表明, 小波方法比对数衰减法和希尔伯特方法具有更好的噪声鲁棒性. 采用小波方法分析了润扬大桥结构健康监测系统获得的实测数据, 识别出了润扬大桥悬索桥前6阶模态参数, 第2阶和第3阶模态频率相差仅为0.015\,Hz. 研究表明, 小波方法具备噪声条件下密集模态的识别能力, 是工程中阻尼识别的优选方法. 相似文献
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AbstractIn this paper, details of the design work for a tuned vibration absorber to be used on a hollow cylindrical structure is presented. The vibration problem is of resonant type and the tuned vibration absorber is designed to suppress the displacement vibration response of the free end of the slender hollow structure dominated by the contribution of its lowest transverse vibration modes. The structure is modeled using a commercial finite element software. Finite element model of the structure is verified using experimentally obtained frequency response functions and modal parameters. Effective parameters of the tuned vibration absorber design are then determined based on finite element analysis simulations of the vibration suppression performance of the tuned vibration absorber as it is used on the structure. Details of the tuned vibration absorber design are determined and a prototype is fabricated. Prototype tuned vibration absorber is then characterized experimentally both as a standalone system and also as it is used on the main structure. Vibration reduction performance of the physical prototype of the tuned vibration absorber is also compared with its vibration reduction performance estimated from finite element analysis simulations so that the analysis based design process can be validated.Communicated by Dumitru Caruntu. 相似文献
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Ali Taheri 《Archive for Rational Mechanics and Analysis》2010,197(1):239-270
Let X be a [generalised] annulus and consider the space of continuous self-maps of X, that is,
${\mathfrak A}({\bf X}) := \left\{ \phi \in {\bf C}({\bf X}, {\bf X}) : \phi(x) = x \mbox{ for ${\mathfrak A}({\bf X}) := \left\{ \phi \in {\bf C}({\bf X}, {\bf X}) : \phi(x) = x \mbox{ for 相似文献
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Dongho Chae 《Journal of Mathematical Fluid Mechanics》2010,12(2):171-180
Let v and ω be the velocity and the vorticity of the a suitable weak solution of the 3D Navier–Stokes equations in a space-time
domain containing z0=(x0, t0)z_{0}=(x_{0}, t_{0}), and let Qz0,r = Bx0,r ×(t0 -r2, t0)Q_{z_{0},r}= B_{x_{0},r} \times (t_{0} -r^{2}, t_{0}) be a parabolic cylinder in the domain. We show that if either $\nu
\times \frac{\omega}{|\omega|} \in
L^{\gamma,\alpha}_{x,t}(Q_{z_{0},r})$\nu
\times \frac{\omega}{|\omega|} \in
L^{\gamma,\alpha}_{x,t}(Q_{z_{0},r}) with $\frac{3}{\gamma} + \frac{2}{\alpha} \leq 1, {\rm or} \omega \times
\frac{\nu} {|\nu|} \in L^{\gamma,\alpha}_{x,t} (Q_{z_{0},r})$\frac{3}{\gamma} + \frac{2}{\alpha} \leq 1, {\rm or} \omega \times
\frac{\nu} {|\nu|} \in L^{\gamma,\alpha}_{x,t} (Q_{z_{0},r}) with
\frac3g + \frac2a £ 2\frac{3}{\gamma} + \frac{2}{\alpha} \leq 2, where Lγ, αx,t denotes the Serrin type of class, then z0 is a regular point for ν. This refines previous local regularity criteria for the suitable weak solutions. 相似文献
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A procedure for identifying the dynamic parameter of offshore platform is presented. The present procedure consists of two
key features. First uses random decrement (RD) technology to extract free vibration signal in strong noise environment in
which it may not white noise. Second technology which called autoregressive moving average (ARMA) was used to model the data
treated by the random decrement method. In order to get rid of the color noise in the output signal response from the offshore
platform an imaginary system is added in RD system and make the course of extracting performed under the state of color input
by choosing the breakover condition and lead time. For eliminating multi-values of parameters identified, an updating moving
average method is used. The dynamic parameters of structure under arbitrary input are identified. Example of the method as
applied to a scale-model offshore platform was used to evaluate the technology of efficiency and the value of on-line.
Foundation items: the National Outstanding Youth Science Foundation of China (59625815); the Applied Development Foundation of National High
Technology
Biography: OU Jin-ping (1959-), Professor, Vice-President, Doctor 相似文献
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This paper is devoted to study a coupled Schr?dinger system with a small perturbation $$\begin{array}{ll}u_{xx} - u + u^{3} + \beta uv^{2} + \epsilon f( \epsilon, u, u_{x}, v, v_{x}) = 0 \quad {\rm in} \, {\bf R}, \\v_{xx} + v - v^{3} + \beta u^{2}v + \epsilon g( \epsilon, u, u_{x}, v, v_{x}) = 0 \quad {\rm in} \, {\bf R} \end{array}$$ where β is a constant and ε is a small parameter. We first show that this system has a periodic solution and its dominant system has a homoclinic solution exponentially approaching zero. Then we apply the fixed point theorem and the perturbation method to prove that this homoclinic solution deforms to a homoclinic solution exponentially approaching the obtained periodic solution (called generalized homoclinic solution) for the whole system. Our methods can be used to other four dimensional dynamical systems like the Schr?dinger-KdV system. 相似文献
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基于$k$-$\omega$的SST两方程湍流模型, 求解雷诺平均N-S方程获得定常和非定常气动力, 耦合
翼型弹性振动方程, 在时间域内模拟了不同的翼型非定常流动, 重点研究了大迎角下的分离
流问题, 研究结果表明: 在百万雷诺数条件下, 由于振动引起分离涡的不规律脱落, 可能导
致气动力平均值的变化; 而厚度大于20\%的翼型在一定大迎角范围内, 会出现分离涡流场平
衡态的转化, 从流体力学稳定性的角度, 解释了风洞实验中大迎角气动力数据的分散性, 为
大迎角气动力风洞实验的重复性和数据分散性给出了一种新解释. 相似文献
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