【作者】 雷松；

【导师】 王时龙；

【作者基本信息】 重庆大学 ， 机械电子工程， 2010， 博士

【摘要】 多股螺旋弹簧(简称多股簧)通常是由2 ~ 7股0.5 ~ 3mm的碳素弹簧钢丝拧成钢索冷绕而成,分为有中心股和无中心股两种结构形式,其中压缩弹簧的钢索的旋向与弹簧的旋向相反,拉伸弹簧的旋向与弹簧的旋向相同。与普通单股螺旋弹簧相比,多股簧具有强度条件好、吸振减振性能优越等独特性能,因而它是航空发动机和自动武器等产品的关键零件。另外,多股簧还可广泛应用于振动设备(如振动筛、振动粉碎设备等)、高精度台面和要求很平稳的运输车辆等,以取代传统的单股弹簧和橡胶弹簧。到目前为止,已有文献对多股簧的静态响应和成形方法进行了相关研究。而多股簧在工作过程中主要承受冲击载荷,其优越性能在于弹簧变形时钢丝之间的接触摩擦所产生的阻尼效果,因此多股簧承受冲击载荷时的动力学响应以及钢丝间的磨损机理分析应成为研究的重中之重,但还未有针对此方面的研究工作。本文旨在通过对多股簧冲击特性和损伤机理的研究,深入多股簧的相关理论研究基础,重点在于多股簧承受冲击载荷时的有限元数值计算及其相应的几何模型理论基础、冲击试验检测设备的研制、钢丝间的扭动微动磨损机理试验研究及有限元分析。本文主要从以下五个方面对多股簧的冲击特性及损伤机理进行了深入、细致的研究和探讨工作:首先,多股簧的钢索拧角和钢索直径大小从根本上决定了多股簧的性能。现有文献提出的“相邻两根钢丝中心线的最短距离等于钢丝直径”和“钢索横截面为椭圆相切”的计算方法均有局限性。因此,本文通过新建立的多股簧钢索横截面的精确数学模型,利用MATLAB软件开发了应用软件来直接精确求得任意股数的多股簧钢索拧角和直径。同时,在现有多股簧各股钢丝中心线数学模型基础上,基于连续多段函数和指数方程方法,分别采用CATIA和PRO/E软件的螺旋扫描功能,建立了两段并圈多股簧的三维实体模型,为后续多股簧的动态设计理论、冲击特性的有限元计算提供了重要的理论基础和计算模型。第二,多股簧的冲击特性是研究的热点。在两段并圈多股簧的三维实体模型基础上,通过对多股簧运动工况的分析,建立了受阻尼影响的多股簧动态模型振动方程。同时,利用ABAQUS软件的显式动态功能进行高速冲击响应分析,为多股簧的结构优化设计提供了依据。第三,研发了多股簧动态参数非接触高速多通道检测系统的结构、电气硬件及控制算法,该系统可用于检测多股簧在冲击振动状态下,簧杆上各质点的运动位移、速度、加速度,从而获得多股簧簧圈各质点的动态参数,为多股簧在高速冲击载荷作用下其内部的变形过程研究提供试验检测平台。第四,针对扭动微动是导致多股簧钢丝表面局部区域磨损的重要原因之一,通过各股钢丝间法向接触力及角位移的数学模型所得到的试验参数,在新型试验装置上真实模拟了多股簧工作过程中钢丝间发生的柱-柱接触扭动微动;系统研究了不同试验工况及循环次数的变化对多股簧钢丝扭动微动运行行为和损伤机理的影响。最后,在试验研究的基础上,对多股簧钢丝扭动微动进行数值模拟,研究不同试验工况、循环次数和接触面摩擦系数条件下,接触界面应力、相对滑移的分布和变化情况;通过修正的Archard方程建立多股簧钢丝扭动微动工况下的磨损模型,采用与数值模拟相结合的方法计算不同试验工况及循环次数下钢丝的磨损深度;并结合与前面试验结果的对比分析,对多股簧扭动微动磨损损伤机理的深入认识提供参考。更多还原

【Abstract】 Stranded-wire helical spring is a cylindrical helical spring rolled by a strand, which usually consists of 2 to 7 carbon steel wires of 0.4 to 3 mm in radius. The spring has two kinds of structures in accordance with whether it has central wire or not. The helical direction of the compression spring is opposite to that of the strand, while it has the same direction for the extension spring. Compared with conventional single helical springs, it has the unique characteristic of better damping and vibration reduction. Therefore, it is a critical part in aero engines and automatic weapons. In addition, the spring is widely used in vibratory equipments, such as vibration sieves and vibration breaking plants, high precision table-boards and steady transport vehicles, substituting traditional single springs or rubber springs.So far, the static response and formation of stranded-wire helical spring have been widely researched. However, researchers seldom cover the impact performance and wear mechanism, so the analysis of dynamic response and wear mechanism among spring wires is the most important aspect for the study of the spring. The super performance of stranded-wire helical spring mainly results from the damping effect generated by frictions of the strand and the wire when the spring mainly bears impact load during to-and-fro movement. The present thesis further perfects correlation theory of stranded-wire helical spring through the study of impact performance and wear mechanism of the spring, and concentrates on the theory of theoretical geometric model and corresponding numerical simulation when stranded-wire helical spring mainly bears impact load, the development of testing device, torsional fretting wear mechanism and FEM numerical calculation among spring wires.The present thesis makes efforts to detailed studies on the impact performance and wear mechanism of the spring from the following aspects:Firstly, the performance of stranded-wire helical spring is basically determined by its twist angle and wire diameter. The numerical methods raised in the existing simplified theory that the minimum distance between two adjacent wires is equal to wire diameter and the strand cross-section is elliptical tangent are not sufficient. An application software adapting newly established mathematic model about the strand cross-section is developed to calculate the precise twist angel and diameter of strands of arbitrary wires. Meanwhile, based on the mathematical model of curve for centre line of spring wire, the present thesis establishes the three dimensional entity model of stranded-wire helical spring of closed ends, adapting helical scan function of CATIA and PRO/E respectively, which provides the significant theoretical principle and calculation model for following dynamic design theory and numerical impact simulation.Secondly, the dynamic performance of stranded-wire spring is hot issue for study. Based on the three dimensional entity model of stranded-wire spring of closed ends and the motion analysis of the spring, this paper sets up a dynamic vibration equation considering the damping effect. The high-speed impact response analysis by using the implicit dynamic function of ABAQUS gives a significant reference for the optimum structure design of stranded-wire spring.Thirdly, a high-speed, non-contact and multi-channels device for testing the dynamic parameters of the spring is developed. The displacement, velocity and acceleration of every particle in the spring can be directly calculated with high precise by using the mentioned testing system, which offers a detection platform for the analysis of internal modification of stranded-wire spring under high-speed impact.Fourthly, the wear on the local area of the steel wires’surface is due to the torsional fretting on the working process of the stranded-wire helical spring. Two mathematical models to calculate the normal contact force among the wires and the angular displacement respectively are established at first when the stranded spring bore impact load. With the experimental parameters obtained from the models, the torsional fretting test adopting cylinder - cylinder contact mode, which authentically stimulates the torsional fretting among the wires on the working process of the spring, is realized successfully on a newly developed fretting tester. The running behavior and the failure mechanism of the spring wires under the torsional fretting conditions are systematically researched.At last, based on the experimental research, the distribution of stress and relative slip in the contact area through the torsional fretting numerical calculation of spring wires under different test conditions, cycles and friction coefficients is obtained. Combining the mathematical wear model adapting the modified Archard equation and the numerical simulation, the wear depth is able to be accurately calculated under different work conditions and cycles. Comparison the numerical simulation with the experimental results can provide significant reference for the further study of wear mechanism of stranded-wire helical spring under torsional fretting condition.更多还原