基于ANSYS的多股螺旋弹簧有限元分析

简单分析多股螺旋弹簧的基本特性。以三股钢丝的多股螺旋弹簧为例,通过有限单元与接触单元的选取和网格的划分,建立多股螺旋弹簧有限元模型。然后对其进行静态受力分析和动态分析计算,分析冲击载荷质量和速度对多股螺旋弹簧性能的影响。结果表明多股螺旋弹簧在动态系统中具有内部振动波,并可能在中间产生并圈现象,为多股螺旋弹簧设计提供了依据。     

多股螺旋弹簧动态计算分析

结合多股螺旋弹簧的静态设计方法,重点考虑动态性能要求,提出一种静态与动态相结合的设计模型.根据多股螺旋弹簧自身质量对运动的影响,推导弹簧虚拟质量的计算方法,并分析多股螺旋弹簧的动态特性,计算多股螺旋弹簧作为复进簧模型的运动规律.按照多股螺旋弹簧的振动位移特性,以多股螺旋弹簧动态工作过程的并圈作为边界条件进行动态设计计算.最后给出一个完整的动态设计计算实例,结果证明了所提出方法的有效性,从而为多股螺旋弹簧动态应用提供了设计依据.     

Design and Modeling on Stranded Wires Helical Springs

A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires helical spring has the notable predominance in strength, damping and vibration reduction, which is usually used in aircraft engines, automatic weapons, etc. However, due to its complicated structure, the precise computation of its strength and rigidity need be a correct mathematical model, which then will be imported to finite element analysis software for solutions. Equations on solving geometric parameters, such as external diameters of strands and screw pitches of wires, are put forward in the paper. It also proposes a novel methodology on solving geometric parameters and establishing entity models of the stranded wires helical spring, which provides foundation of computing mechanical parameters by FEA. Then mathematical models on the centre line of the strand and the surface curve of each wire, after closing two ends in a spring, are proposed. Finally, geometric parameters are solved in a case study, and a 3D entity model of a spring with 3 layers and 16 wires is established, which has validated the accuracy of the proposed methodology and the 3D entity mathematical model. The method provides a new way to design stranded wire helical spring.     

多股簧冲击载荷特性试验研究

以多股簧应用于复进簧时的工况为例,按照质量-弹簧-阻尼模型,建立了多股簧和各个簧圈的冲击响应动力学模型;对多股簧进行了冲击载荷试验,分析了弹簧内部运动规律,并识别出弹簧的等效刚度、等效阻尼等模态参数。试验结果表明：受冲击载荷时,多股簧的结构呈非线性特性,更能体现其减振的优势;弹簧内部运动规律也为非线性,各簧圈的运动速度沿轴向不再是线性分布。     

多股螺旋弹簧的动态设计方法

根据多股螺旋弹簧实际动态工作过程的要求，结合静态设计方法，重点考虑动态振动特性，提出了一种动态设计方法。首先确定多股螺旋弹簧的虚拟质量，建立了多股螺旋弹簧的动态模型。在此基础上，将多股螺旋弹簧作为复进簧，对其振动特性进行了分析，以塑性变形作为动态边界条件进行了动态设计约束分析，从而给出完整的多股螺旋弹簧的动态设计过程。实例计算验证了该动态设计方法的可行性和有效性。     

多股螺旋弹簧的空间曲线模型研究

通过分析多股螺旋弹簧的成形原理及结构参数,分别采用空间坐标轴变换、坐标轴角度关系、欧拉角度变换三种不同方法建立了多股螺旋弹簧钢丝中心曲线数学模型。以三股钢丝为例,根据建立的空间曲线数学模型和给定的多股螺旋弹簧参数,使用MATLAB软件绘制了多股螺旋弹簧曲线,并利用参数化建模软件Pro/E完成了多股螺旋弹簧的三维实体建模。结果表明,该模型完全符合多股螺旋弹簧的实体模型,为进一步研究多股螺旋弹簧内部的力学特性和研究其动态设计理论提供了重要的理论依据。     

金属橡胶静刚度特性及其力学模型研究

对金属橡胶成形机理和静刚度特性影响因素进行分析,运用螺旋弹簧刚度理论建立了金属橡胶微元弹簧理论模型,并根据试验结果对其进行模型修正。通过理论模型与试验的比较,发现理论模型值与试验值较接近,可以较全面地反映金属橡胶静刚度特性,从而为金属橡胶减振器的设计和金属丝工艺参数的确定提供理论依据。     

Evaluation model for multi-process capabilities of stranded wire

Stranded wire is the most important component of familiar mechanical equipment such as elevators, cable cars, and cranes. The quality of these products that are used on a daily basis are mainly affected by the tensile strength of stranded wire. In order to attain the purpose of economical design and a long life span of stranded wire, a less relaxation property of strand type is suitable for manufactured tools. Thus, the manufacturing industries of stranded wire need to reach the goals of high tensile strength and low relaxation. To ensure the required quality of stranded wire, the strand pull test and the long period relaxation test are two important quality assurance tests. There are three specific items of the tensile strength test that belong to the larger-the-better quality type. The quality type of the smaller-the-better is for the long period relaxation test. However, many existing methods are able to measure process capability for the product with a single quality characteristic although it cannot be applied to most products with multiple properties. Thus, the indices of C_pu and C_pl, for the larger-the-better and the smaller-the-better quality type respectively proposed by Kane [5], are quoted and combined to propose a new index to evaluate the quality of multiple characteristics of stranded wire in this article. The principle of statistics is then used to derive the one-to-one mathematical relationship of this new index and ratio of satisfactory production process. Finally, the procedure and criteria to evaluate the quality of stranded wire is proposed. This integrated multi-quality property capability analysis model can be used to evaluate the multi-process capabilities and provide continuous improvements on the manufacturing process of stranded wire.     

基于不同载荷的圆柱螺旋弹簧刚度特性分析

运用SolidWorks软件本身的建模功能构建弹簧的三维模型,并对圆柱螺旋弹簧进行有限元分析,通过不同的加载方法（位移加载和直接力加载）,获得不同加载方法下螺旋弹簧的刚度。研究表明：Solid-Works分析软件能够获得足够精度的计算结果,并且位移加载更符合理论计算的结果,为圆柱螺旋弹簧的精确设计和计算提供了可靠的方法和依据。     

An experimental study of pressure drop correlations for wire-wrapped fuel assemblies

The main objective of the present study is to perform an experimental evaluation of five existing correlations for the subchannel pressure drop analysis of a wire-wrapped fuel assembly. For this purpose, a series of water experiments have been performed using a helical wire-wrapped 19-pin fuel assembly for various test parameters. For different test sections with different pitch to rod diameter ratios (P/D) and wire lead length to rod diameter ratios (H/D) have been fabricated. A series of pressure drop measurements were made to obtain friction factors for these four test sections. The new data along with existing data are used to evaluate existing correlations. Both the original and the simplified Cheng and Todreas correlations give the best agreement with experimental data for all flow regions.     

Maximum principal tensile stress and fatigue crack origin for compression springs

Contrary to the traditional concepts, for helical compression springs with a large coil radius to wire radius ratio, the most highly stressed region is at the outer surface of the helix rather than inside. The likely fatigue crack origin is also located on the outer surface of the helix where the maximum amplitude of the principal tensile stress was calculated during cyclic loading. An equation is proposed for the maximum tensile stress from loading of a helical spring, and a method is presented to calculate the likely fatigue crack origin. It is demonstrated that for high-stressed springs, fatigue design should be based on the range of the maximum principal tensile stress. The influence of the shot peening on the location of the fatigue crack origin is also investigated.     

矩形钢丝圆柱螺旋弹簧的简化设计法

对设计矩形钢丝圆柱螺旋弹簧涉及的刚度、应力计算公式中的变化系数进行了一元线性回归。找出了这些系数的变化规律，给出了计算这些系数的回归计算式，从而简化了矩形钢丝圆柱螺旋弹簧的设计计算方法。回归分析表明，利用简化后的设计公式与传统的设计公式比较，相对误差小，使用起来与圆钢丝圆柱螺旋弹簧的设计方法一样方便，不需查找在计算弹簧刚度和应力时所需的弹力附加系数和应力附加系数，从而简化了设计，提高了工作效率。     

A new model in rail-vehicles dynamics considering nonlinear suspension components behavior

In this paper, a complete four axle rail vehicle model is addressed with 70 degrees of freedom (DOFs) including a carbody, two bogies, and four axels. In order to include the effects of the track irregularities in vehicle dynamics behavior, a simplified track model is proposed and it is validated by some experimental data and test results. As the performance of the suspension components, especially for air springs, have significant effects on rail-vehicle dynamics and ride comfort of passengers, a complete nonlinear thermo-dynamical air spring model, which is a combination of two different models, is introduced and implemented in the complete rail-vehicle dynamics. By implementing Presthus formulation [Derivation of air spring model parameters for train simulation. Master dissertation, Department of Applied Physics and Mechanical Engineering, Division of Fluid Mechanics, LULEA University, 2002], the thermo-dynamical parameters of air spring are estimated and then they are tuned based on the experimental data. The results of the complete rail-vehicle field tests, show remarkable agreement between proposed model and test data.     

双腔室空气弹簧的实验建模

分析了双腔室空气弹簧工作过程中各物理量的变化,依据绝热过程中的能量交换推导了双腔室空气弹簧的理论模型.为了提高模型的精确性,对单自由度空气弹簧实验装置进行实验,使用LMS采集系统获取输入量和输出量,得到双腔室空气弹簧的实测传递函数.在实验数据的基础上分析了密封膜结构对空气弹簧模型的影响,提出了改进的模型,并通过参数识别方法确定未知参数的值.最后将改进模型与理论模型及实测数据进行对比,证明了改进模型的有效性.     

Identification of pseudo-natural frequencies of an axially moving cantilever beam using a subspace-based algorithm

This study focuses on extraction of frequency information of a linear time-varying system using free response data. Frequency information is obtained from the pseudo-modal parameters that were defined in a previous study. A subspace-based identification algorithm is introduced. An improved version is proposed to make the algorithm less sensitive to measurement noise. An axially moving cantilever beam is used as the experimental system. A dynamic model is presented to show that lateral vibration of the axially moving cantilever beam is governed by a linear time-varying model. A computer simulation is conducted to compare the true pseudo-modal parameters and approximate ones that can be identified using the improved algorithm. The experimental study focuses on the capabilities of the algorithm and the factors that affect the identification results. A method of grouping identified structural pseudo-natural frequencies is proposed. Limitations of the algorithm are discussed.     

螺旋弹簧悬架车辆振动的波动理论建模及频响分析

针对车辆建模不能完全反映高频振动的情况,应用古典振动理论及冲击波动理论,对螺旋弹簧悬架车辆的振动进行模拟并对响应进行分析。提出用冲击波动力学分析车辆振动的理论依据,推导螺旋弹簧应力波波阻的表达式,由此建立车辆的波阻力及变形力振动模型。通过冲击波影响螺旋弹簧的长度及其对应的质量,建立了螺旋弹簧惯性力及变形力车辆振动模型,综合多种因素,建立螺旋弹簧悬架车辆振动的波动理论模型,探讨了模型的求解方法,并对各种模型从理论和解法两个方面进行对比。仿真验证冲击波动理论模型与古典振动理论模型在低频段的一致性及弥补后者不能表达高频振动的缺陷。提出了在波动理论下螺旋弹簧多参数的应用方法及悬架高频响应的模拟方法。     

一种基于参数影响的数据驱动下的疲劳寿命预测方法

金属构件的主要失效方式是在循环载荷作用下的疲劳破坏,因此金属构件的疲劳寿命预测对于保证结构安全性和可靠性十分必要。能量法是一种既能用于低周疲劳寿命预测,也能用于高周疲劳寿命预测的方法,其以寻找有效的显式能量损伤参量为手段,结合适当的损伤积累方式进行寿命评估。针对材料疲劳寿命预测问题,提出一个基于能量法和人工神经网络算法的疲劳寿命预测方法。为了达到反映不同加载路径影响的目的,从转动惯量的角度引入两个路径相关参量。使用基于应变控制的九种材料的疲劳试验数据对提出的神经网络模型进行训练、测试。结果显示模型对训练数据和测试数据均有良好的预测精度,并可对单轴加载、多轴加载、高周疲劳和低周疲劳寿命进行有效预测,表明本模型在多轴疲劳寿命预测方面具有较广泛的适用性。     

基于改进前馈逆补偿的电液加载试验系统力跟踪控制研究

针对电液加载试验系统力加载跟踪控制问题，分析了电液加载系统的组成及工作原理，建立了系统动力学模型，并对动力学模型的准确性进行了验证。在此基础上，首先使用了速度反馈补偿控制器抑制外部干扰，其次利用递推增广最小二乘法(Recursive Extended Least Square，RELS)及零相差跟踪技术(Zero Phase Error Tracking，ZPET)设计出系统逆模型，进行前馈逆补偿控制，然后考虑速度反馈存在的微分问题，设计了内模控制器，最后利用电液加载试验台进行了力加载控制策略的试验研究。试验结果证明，与传统PI控制器相比，提出的改进前馈逆补偿力加载控制算法可以更有效地抑制系统外部干扰，提高力加载的跟踪精度。     

Identification of nonlinear hysteretic systems by artificial neural network

An identification method is developed for nonlinear hysteretic systems by use of artificial neural network in the paper. Employing the Bouc–Wen differential model widely used for memory-type nonlinear hysteretic systems, the approach sets up a Bouc–Wen model-based neural network. The weights of the designed specifically network correspond to the Bouc–Wen model parameters and are thus physical ones. Taking advantage of powerful function approximation capability of neural network, the nonlinear hysteretic systems can be identified with the proposed approach by network training. The identification scheme is validated by a simulated case and thereafter applied to modeling of a wire cable vibration isolation experimental system. The results show that the presented identification method can identify the nonlinear hysteretic systems with high accuracy.