【作者】 刘欢；

【导师】 陈思雨；

【作者基本信息】 中南大学 ， 机械工程， 2024， 硕士

【摘要】 枪械作为冲击机构的典型代表,击发过程时间短且冲击载荷变化剧烈,机构中存在的复杂冲击接触和碰撞现象使得对自动步枪多体系统的动力学分析变得非常困难。因间隙存在而导致的冲击会引起振动与噪声,并使机构中各部件的运动难以被精确描述,影响枪械的功能与使用性能,特别是命中精度。因而使用多体动力学的方法研究枪械中各运动机构的碰撞对于机构运动特性的影响有非常重要的意义。现有的研究主要关注发射过程中关键部件的受力及工作状态,忽视枪械内部各机构的连续运动的时序性及动力学行为。本论文以自动步枪发射机构为研究对象,构建基于非线性弹簧阻尼模型的发射机构运动过程动力学模型和连续碰撞过程动力学模型,研究发射机构参数对于动力学特性的影响,对该型自动步枪发射机构研究与运动过程分析提供重要参考。主要研究内容为:(1)以球体碰撞过程为例详细分析了冲击碰撞问题计算过程,基于连续接触力法推导了使用碰撞接触点坐标的部件间隙、接触变形与碰撞速度表示方法,提出接触变形函数,统一了分离状态与碰撞状态的系统动力学方程。(2)使用Adams软件建立自动步枪发射机构运动仿真模型,通过设置传感器与驱动自动控制部件运动与配合过程,得到符合发射机构实际情况的仿真模型,分析了发射机构运动时序与部件间的配合关系。(3)基于非线性弹簧阻尼建立发射机构冲击碰撞动力学模型,提出了适用于连续接触力法的碰撞检测方法,将系统状态分为“接触-碰撞-分离”三种状态,提出了接触变形函数了统一分离状态和碰撞状态下的系统动力学方程,使用Matlab软件中的event函数检测接触状态实现分离状态与碰撞状态计算过程的衔接,完成动力学模型计算并分析了复进弹簧刚度与载荷大小对发射机构运动过程的影响。(4)基于非线性弹簧阻尼模型与小变形假设建立考虑库仑摩擦的偏心斜碰撞系统动力学模型,使用库仑摩擦理论实现了碰撞过程法向与切向接触行为的联系,计算结果与有限元仿真结果吻合程度较好,击针速度和碰撞时刻的计算结果较为准确。(5)建立单次发射过程发射机构连续碰撞动力学模型,研究加载延迟、碰撞恢复系数、复进弹簧参数与初始间隙对连续发射过程中发射机构动力学特性的影响,并分析了影响机理。图109幅,表26个,参考文献96篇更多还原

【Abstract】 As a typical representative of the impact mechanism,rifles have a short duration and severe changes in impact load during the firing process.The complex impact contacts and collisions within the mechanism make it difficult to accurately describe the motion of the components,affecting the functionality and performance of the firearms,particularly the accuracy.Therefore,studying the impact of collisions in firearm mechanisms using multi-body dynamics methods is of great significance for understanding their motion characteristics.Current research primarily focuses on the forces and operational states of key components during the firing process,overlooking the sequential and dynamic behaviors of internal mechanisms.This thesis focuses on the firing mechanism of automatic rifles,developing dynamic models for the firing process and continuous collision based on a nonlinear spring-damper model,to study the impact of mechanism parameters on dynamic characteristics,providing a crucial reference for the analysis and study of this type of automatic rifle’s firing mechanisms.The main research includes:(1)The impact collision process was analyzed in detail using the example of the spherical collision process,and a method based on continuous contact force model was developed to represent component clearance,contact deformation,and collision velocity using contact point coordinates.Additionally,a function for contact deformation was proposed to unify the system dynamics equations in both separation and impact states.(2)An automatic rifle firing mechanism motion simulation model was established using Adams software.Sensors and motions were set up in the simulation model to control component movement and coordination process of the components automatically.The motion timing sequence of the firing mechanism and the cooperative relationship between the components were analyzed.(3)Based on the nonlinear spring damping model,an impact collision dynamic model of the firing mechanism was established.A collision detection method suitable for the continuous contact force method was proposed,which divided the system state into three states:"contact-collision-separation."A contact deformation function was introduced to unify the system dynamics equations under the separation state and collision state.The event function in Matlab software was used to detect the contact state and achieve the connection between the calculation processes of the separation state and the collision state.The dynamic model was calculated,and the influence of the stiffness of the recoil spring and the magnitude of the load on the movement process of the firing mechanism was analyzed.(4)Based on the nonlinear spring damping model and the hypothesis of small deformation,the dynamics model of eccentric oblique impact system considering Coulomb friction was established.The contact behavior of normal and tangential contact was connected by using Coulomb friction theory,the calculated results were in good agreement with the finite element simulation results,and the calculated results of firing pin speed and collision time were relatively accurate.(5)A dynamic model of the firing mechanism for continuous collisions during a single firing process was established.The study investigated the effects of loading delay,collision restitution coefficient,recoil spring parameters,and initial clearance on the dynamic characteristics of the firing mechanism during continuous firing,and analyzed the influence mechanisms of these parameters.更多还原