应用逆子结构方法确定包装耦合体动态特性

应用动态逆子结构分析理论,针对"产品-包装耦合-运载体"系统中的包装耦合体,提出一套基于系统与部件实验测量的耦合动态特性分析计算新方法,包括直接逆子结构法和间接逆子结构法.应用集总参数模型及部分实验结果检验该套技术方法的有效性.这两种方法是为实际包装耦合体的设计及其缓冲防震性能的评价而提出的.     

离散化包装耦合体动刚度的逆子结构计算方法

提供离散化包装耦合体的动刚度一种间接的逆子结构计算方法,依据矩阵理论建立复杂包装耦合体等效离散化后动态刚度逆子结构分析计算方法及其普适性公式。应用典型运输包装系统的集总参数模型验证公式的完备有效性,并计算源函数（频率响应函数）误差的影响。     

产品-包装-运载体系统动态特性研究

为缓冲防震系统的设计与评估提供一种新的结构动态分析方法,将复杂耦合结构系统的动态逆子结构分析方法应用于运输包装工程中.从系统分析的角度建立用于确定"产品-包装-运载体"在系统与部件水平的动态特性的实验技术理论.通过对一个集总参数模型实例在系统水平的传递函数的计算,验证了所建立理论的有效性.     

离散化包装耦合体动刚度的间接逆子结构分析计算方法

提供一种间接计算离散化包装耦舍体动刖度的逆子结构分析计算方法,依据矩阵理论推导了计算公式.该方法采用工程应用中较易测量或测量误差相对较小的系统水平和部件水平频率响应函数(FRF)进行分析计算,可有效提高计算精度和应用于运输包装系统动态优化设计的可行性.以典型运输包装系统的集总参数模型验证了公式的完备有效性,并比较了动刚度的直接与间接逆子结构分析计算因FRF测量误差所造成的结果偏差.     

运输包装车辆装配系统直接与间接逆子结构动态分析方法实验验证

针对"产品-包装-车辆"装配系统中的包装耦合体,基于系统与部件水平的实测频率响应函数(FRF),计算了装配耦合动刚度,包括直接逆子结构法和间接逆子结构法。设计了一套实验模型并测量、计算和分析了其系统装配耦合动刚度,实验验证了这2种方法在实际包装耦合体的设计及其缓冲防震性能分析上应用的有效性。     

多点刚性耦合产品包装运输系统间接逆向子结构分析

在实际测量过程中,产品包装运输系统的耦合界面处通常空间结构复杂,导致该处的频率响应函数难以测得。针对该问题,提出基于多点刚性耦合产品包装运输系统的间接逆子结构方法,该方法无需测得系统耦合界面处的频响函数即可求得未知子系统(产品/关键部件)在耦合点处的频响函数。基于动力学微分方程和线性叠加原理建立系统与子结构的力与位移关系,再通过矩阵变换,分别得到了用于不同刚性耦合包装运输系统的间接逆子结构方法公式。建立集总参数模型,验证该算法的正确性。结果表明该方法在运输包装领域具有优秀的可行性和应用前景。     

多部件耦合包装系统逆子结构分析一般性理论

建立多部件耦合包装系统动力学模型,建立其动力学分析的一般逆子结构方法,得到从系统水平传函反向计算各耦合部件水平传函及部件间耦合动刚度的理论公式,采用集总参数模型数值校验了所建立理论的正确性。研究结论为复杂系统动力学特性分析提供了一种新的技术方法。     

逆子结构理论在运输包装中的研究进展

微动态逆子结构方法在解决由产品、包装和运载体(如车辆)组成的产品运输包装系统的相关问题上效果显著。综述了运输包装中逆子结构理论的发展与完善及其在其他方面的应用成果、测量信息不完备下的逆子结构分析以及间接逆子结构分析。逆子结构理论的发展为了解运输过程中产品的动态特性提供了新的方法,也为今后运输包装的进一步发展提供了参考。     

一种针对含非线性子结构多点耦合运输包装系统的解耦方法

目的 考虑到运输包装系统耦合形式复杂,包装材料及包装结构具有非线性特性,不容易测量局部物理参数,需要对传统逆向子结构方法进行优化,使之能够求解非线性多点耦合系统中子结构的动态响应特性。方法 使用描述函数法将非线性的运输包装系统线性化,测量其在若干特定振动幅值下的频率响应函数;之后,应用逆向子结构方法和参数识别方法,计算包装件的模态参数;最后,拟合包装件模态参数与振动幅值之间的关系,构建函数来描述包装件的动态响应特性。结果 在集总参数模型中,解耦预测值与实际值吻合;在有限元模型中,对响应峰值的预测误差小于5%,对响应跳跃现象所在频率的预测误差小于3%。结论 该研究将传统逆向子结构方法的应用范围拓展到了非线性多点耦合系统,对复杂运输包装系统动力学模型的构建和防振包装的设计具有指导意义。     

多级刚性包装运输系统间接逆向子结构分析

目的针对各子部件耦合界面之间的系统水平频响函数难以测量,刚性耦合系统逆向子结构分析方法无法顺利应用的情况,提出多级系统间接分析方法。方法基于子结构理论,提出单点耦合和多点耦合系统的多级刚性耦合系统间接逆向子结构分析方法,然后建立相对应的集总参数模型,利用已知参数和公式获得部件频响函数直接计算值和预测值,最后将两者进行对比验证。结果部件频响函数直接计算值与预测值相吻合,验证了方法的准确性。结论提出的方法可为逆子结构理论在解决耦合界面频响函数难测问题时提供新思路,以及为在运输包装领域更广泛的应用提供更多的可能性。     

Dynamic investigation and optimal design of a novel fluid coupling shock absorber for dual demand of vibration and impact safety of precision systems

Summary The aim of this article is to provide a systematic investigation to the design or optimal design of the shock absorber for the protection of a precision system as electronic packaging system in harsh vibration-impact environment. To get the dual demand of resisting violent impact and attenuating vibration in vibration-impact-safety for precision equipment or components, a novel micro fluid coupling damping shock absorber is designed and manufactured through coupling the oil, rubber ball and spring by ingenious tactics. The physical mechanism of the actual shock absorber is systematically investigated. The experimental results of the key-model machine in dynamic tests show complex nonlinear dynamic characteristics. Based on the test, the nonlinear dynamic model for the shock absorber is presented by analyzing the internal fluid dynamic phenomenon with respect to the shock absorber. Comparisons with experimental data confirm the validity of the model. The model is integrated by introducing normalization measure in progress. The approximate formulae are deduced by introducing some transformation tactics. These approximate theoretical formulae include the output response of the system, absolute acceleration transmissibility in vibration or impact, and the maximum relative displacement in impact process etc. So the optimal model for parameters matching the design is built. The parameters matching the design are discussed based on an approximate solution in progress. Finally, an example of the applied product is described.     

爆炸荷载下RC梁系的解析分析

对梁系结构在爆炸荷载作用下的动力计算问题进行了研究,由于支承构件的变形性,梁系结构可归结为第二类的动支座问题。建立了梁系的动支座计算模型,推导并给出了梁系结构分别在弹性阶段和塑性阶段的动力计算公式,分析了影响梁系振动的主要因素和影响规律。研究表明:影响梁系结构振动的主要因素有两个,下部支承结构的基频ω0和无量纲参数ωθ,基频ω0和参数ωθ越大,上部构件的动力系数就越大。当ω0≥5ω时,下部构件对梁系振动的影响可忽略,认为上部构件是刚性支承。     

Oblique and normal perforation of concrete targets by a rigid projectile

The oblique and normal perforation of a concrete target subjected to a rigid projectile impact is studied in this paper. A general three-stages model, i.e., initial cratering, tunnelling and shear plugging, is developed based on dynamic cavity expansion theory and plug formation. Analytical solutions for the ballistic performance and the perforation limit of concrete target are obtained. The proposed formulae are consistent with other empirical formulae and correlate well with the experimental data.     

充砂振动柱动态特性预估

本文对充砂振动柱在基础激励下的动态特性进行了理论和实验研究。把砂作为一种具有均匀密度的连续体,假设砂的弹性模量是砂柱高度的幂函数和砂柱中只存在纵向波,建立了波动方程,导出了原点导纳和传递导纳的理论公式。这个公式亦适用于非常短的砂柱。同时采用阻抗方法推导了充砂振动柱的结构损耗因子表达式。实验值和预估值基本相符。     

Analysis of RC structures subjected to air-blast loading accounting for strain rate effect of steel reinforcement

A new method to calculate the dynamic strength of reinforced concrete (RC) structures, with emphasis on the embedded response of mild steel reinforcement, subjected to air-blast loading is derived. The proposed method is based on a single-degree-of-freedom (SDOF) system with appropriate modification for strain-rate effect. Approximate formulae are used and explained in detail. A numerical example is presented to show how the derived formulae are used for the analysis of concrete structures subjected to air-blast loading.     

Metamodels of production line transient behaviour for sudden machine breakdowns

Production controls based on mean value analysis and steady-state conditions are incapable of making on-time decisions that cope with unexpected dynamic events which are due to interruptions in complex work flow characteristic of modern production lines. One of the most significant dynamic events in production situations is a sudden machine/operator breakdown/outage. Computer simulation is known to be a useful tool for modelling the dynamic response of a system to machine breakdown, but it takes too long to perform its analysis to provide the response time necessary for control procedures. Analytical methods provide formulae which are suitable for real-time analysis, but there are no results available for transient behaviour associated with machine breakdown. Metamodelling is the process of summarizing the results of a simulation study in analytical form. In this paper, we present our metamodels for the dynamic behaviour of both time in system and number in system for a general arrival time, general service time, multi-station, multi-server production line system. The formulae are exponential in nature and are developed through a study of first-order differential equations from system control theory. The constants used in our results are determined off-line through discrete-event simulation analysis. The metamodels themselves are available to on-line users as a predictor of parts that will be delayed because of breakdown(s) as a function of time in the future. The integrated approach of using simulation for modelling system details and analytic method for describing the revealed system transient behaviour is a powerful methodology for analysing large-scale production systems.     

An implicit curve-fitting method for fast calculation of thermal properties of pure and mixed refrigerants

Calculations of refrigerant thermal properties are desired to be very fast and stable in cases of simulation of refrigeration system, etc. The traditional method based on equation of state cannot meet such requirement because of unavoidable iterations in calculation. In this paper, a new calculation method for refrigerant thermal properties is presented. Low order implicit polynomial equations are got by using curve-fitting method at first, and then explicit formulae for calculating refrigerant thermal properties quickly are obtained by getting the analytical solution of these implicit equations. Explicit fast calculation formulae for thermal properties of R22 and R407C, covering the saturated temperature of −6080 °C and superheat of 0–65 °C, are presented as examples. The calculation speeds of the formulae of R22 are about 140 times faster than those of REFPROP 6.01 while the formulae of R407C are about 1000 times faster. The total mean relative deviations of the fast calculation formulae for R22 and R407C are less than 0.02%.     

附加惯容器的层间隔震系统简化分析及地震响应研究

层间隔震技术是一种新的减震控制方法。建立了附加惯容器的层间隔震混合控制系统分析模型,推导了附加惯容器的层间隔震混合控制系统的动力特性公式,分析了模型计算参数对动力特性的影响。建立了基于反应谱的地震响应预测公式,并采用时程分析法进行验证;研究了附加惯容器的层间隔震混合控制系统的响应控制效果,对关键参数的影响进行了分析。研究结果表明:惯容器对层间隔震结构的地震响应具有一定的控制作用,所建立的分析方法能较好预测附加惯容器的层间隔震混合控制系统的地震响应,惯容器可实现对位移及加速度双控制的目标。研究结果可作为附加惯容器的层间隔震结构地震响应预测分析方法,并为层间隔震混合控制系统设计提供参考。     

Analytical estimation of dynamic apertures limited by the wigglers in storage rings

By applying the general dynamic aperture formulae for the multipoles in a storage ring developed by Gao (Nucl. Instr. and Meth. A 451 (2000) 545), in this paper, we give the analytical formulae for the dynamic apertures limited by the wigglers in storage rings and their validities have been confirmed by comparing with numerical simulation results.     

基于并行计算的三自由度并联机床动力学解析模型

基于运动学分析、凯恩动力学方程和数字-符号方法,建立了三自由度并联机床的动力学解析模型.将广义坐标、构件的质量和转动惯量处理为符号量.将动力学模型矩阵的推导问题转化为特定条件下运用运动学和动力学计算公式求解驱动力的问题,由计算机自动生成动力学模型矩阵中的各元素的实时代码.文中引入了一种新的标量矩阵与矢量矩阵的乘法运算,研究了广义坐标和构件的质量对驱动力的影响规律.构造了动力学解析模型的并行算法,节省了计算时间.给出了动力学模型矩阵元素的实时代码生成和驱动力矩与参数关系的具体数值实例.