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具有分布质量的双层隔振系统隔振特性分析 总被引:6,自引:2,他引:4
研究了分布质量对双层隔振系统隔振特性的影响,得到了质量对称分布时六自由度双层隔振系统固有频率及对谐波激励响应的解析表达式,提出了考虑摆动影响时确定隔振参数的实用设计方法并进行了实例计算。 相似文献
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本文借助于有限元计算方法,建立了估计三坐标测量机动态误差的模型,得到了由于分布质量惯性力所引起的主要动态误差,为测量机动态误差补偿提供了一种实用的方法。 相似文献
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质量管理是20世纪30年代发展起来的科学管理理论和方法,而统计学是应用数学的一个分支,主要通过利用概率论建立数学模型,收集所观察系统的数据,进行定量的分析、总结,并进而进行推断和预测,为相关决策提供依据和参考。是利用统计学中的数理统计的方法进行质量管理中产品生产的抽样检验,通过研究样本质量特性的分布规律分析和推断过程质量的变化状况,为科学决策提供了理论依据,这也就是统计分析的作用,它改变了传统的事后控制的质量把关的质量控制方式。数理统计是质量管理的工具,为质量管理的发展打下了基础。 相似文献
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变刚度框—剪结构的自振特性分析 总被引:1,自引:1,他引:0
本文将多阶变刚度框-剪结构分段连续化,在考虑了楼板处的集中质量和楼板时间墙体分布质量后,用传递矩阵法导出结构的频率方程,进而求出了结构的产胆三阶自振频率,本文提出了方法思路清楚,计算方便,精度较高,适用性强,还可以考虑基础变形的影响。 相似文献
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药型罩质量分布对射孔弹穿透性能的影响 总被引:2,自引:0,他引:2
文章用实验的方法研究了石油射孔弹药到罩质质(即密度)分布与射孔弹穿透特性之间的关系.实验中用的是目前国内外普遍使用的金属粉末药型罩,罩质量(即密度)分布情况用γ射线检测仪检测。具体地研究了粉末密度沿药到罩径向以及轴向分布情况对针孔弹穿透深度的影响. 相似文献
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Kathryn G. Severin Bradley A. Roscoe Philip K. Hopke 《Particulate Science and Technology》1983,1(2):183-192
The development of multivariate statistical approaches to receptor models have focussed on factor analysis. Target transformation factor analysis (TTFA) offers the possibility of determining the number of sources and their elemental composition as well as their mass contributions. In this current work, a new approach is presented for calculating the mass contributions of each source to each sample. In addition an approach to estimating the uncertainties in the analysis is introduced. The method is applied to a subset of the Regional Air Pollution Study (RAPS) particulate composition data set for site 203 in July and August 1976. The data is divided into subsets covering the daylight (6 AM to 6 PM) or night (6 PM to 6 AM) samples. Similar source profiles are obtained for these subsets. 相似文献
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提出了颤振导数的“参数弹性”概念;基于复模态理论,计算了平板颤振导数的平板宽度、质量、质量惯矩、竖弯频率、扭转频率和空气密度6种参数弹性;绘制了8个颤振导数的参数弹性曲线和诺模图,分析了各自特点,获得了无量纲参数对颤振导数参数弹性的影响规律。分析结果表明,新提出的参数弹性具有概念无量纲、简洁、直观、实用特点,为颤振导数参数分析提供了一种新的有效途径。 相似文献
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合肥电视塔TMD风振控制的响应分析 总被引:2,自引:0,他引:2
本文进行了合肥电视塔风振响应分析,探讨了电视塔人体舒适度设计准则。计算表明,电视塔上塔楼的加速度响应大大超出了容许的最大加速度限值。因此,利用塔上60t重的生活、消防用水箱作为调频质量阻尼器(TMD)。通过在频域内大量的TMD参数研究,确定TMD的优化参数。研究结果表明,具有最优参数TMD可以显著提高电视塔的人体舒适度性能,上塔楼的加速度响应下降了49%。在此基础上,本文提出了TMD优化参数的选择路线,结合受控和未控结构的响应比与频率比和TMD阻尼比的关系曲线,采用图解法确定了满足减振要求的TMD优化参数。 相似文献
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We present in this paper an iterative method using consistent mass matrix in axisymmetrical finite element analysis of hypervelocity impact. To retain the advantage of integration on an element-by-element basis which is at the heart of modern hydrocodes, we suggest that the first step should be to solve for accelerations at an advanced time step by using the lumped mass approach, then iterate using a consistent mass matrix to improve the estimate. Examples are given to show the improved resolution with the new method. 相似文献
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首先导出薄板在附加集中质量时的横向弯曲自由振动方程,应用差分法解出它在三边自由和一边固支的边界条件下的基本频率。进而给出它与悬臂矩形薄板基本频率间的相关关系,除实验验证该关系外,本文还探讨用加速度计测量板材弹性模量E的途径。 相似文献
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A numerical method for the optimal design of thin anisotropic laminates is presented, layer thicknesses and lamination angles being the design variables. An optimal solution is pursued with respect to frequency domain objectives, e.g. fundamental frequency and Euler critical load. A special feature of the method is the semi-analytical second order design sensitivity that is computed with the aid of a Rayleigh-Ritz analysis approach. A modified sequential quadratic programming scheme is then introduced, where standard quasi-Newton approximations are avoided by an exact calculation of the Hessian matrix. Furthermore, the robustness of the method with respect to scatter in material properties such as mass density and elastic moduli is assessed. A stochastic extension of the Rayleigh-Ritz approach is developed on this purpose that allows the location of those regions in the design space that are most sensitive to physical parameter randomness. This allows the use of a modified objective function that penalizes sensitive solution. 相似文献
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Measurements of local velocity, density, and mass flow of phases of a gas-solid suspension are needed in determining transport properties, validating theoretical predictions, and formulating design procedures. Most of the available instruments are based on time averages or fluctuations with time. Primary standard for direct measurement of density of a phase such as solid particles is being developed. A laser phase Doppler device, within certain restrictions, may give local instantaneous density, while other optical methods and neutron beam remain secondary standards based on mass flow calibrations. An overall review including recent results has been made on both intrusive and non-intrusive instruments; their limitations and future possibilities are outlined and discussed. The limitations of the traditional approach utilizing the triangular relation between local averages of mass flow, velocity, and density of particles for the determination of flow properties, and higher order correlations are demonstrated. 相似文献
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层状土层随机地震反应分析的近似解法 总被引:1,自引:0,他引:1
基于模态摄动方法,提出了层状土层随机地震反应的近似分析方法。该方法首先利用等效均匀剪切梁的模态和频率,将层状土层的微分方程转化为代数方程,得到层状土层的固有频率和模态。在此基础上,推导了层状土层随机地震反应的计算公式。最后通过算例,阐述了基于模态摄动法进行随机地震反应的计算过程并分析了该方法的计算误差。计算结果表明,这一方法简单有效,其误差可控制在5%以内。 相似文献