【作者】 张莉洁；

【导师】 钱林方； 王炅；

【作者基本信息】 南京理工大学 ， 机械设计及理论， 2008， 博士

【摘要】 火炮与自动武器发射时,由于高温高压火药燃气的瞬时作用产生的强冲击载荷将引起武器发射时的振动和跳动,影响着射击精度和稳定性。武器系统中采用反后坐原理对发射时的冲击作用载荷进行有效控制。面对现代武器向大威力,轻量化及高机动性的发展要求,被动式的液压阻尼缓冲装置越来越显示出它的不足和局限性。随着材料科学的发展,以智能材料磁流变液为工作介质的磁流变阻尼器,相比传统的被动阻尼缓冲装置,其输出阻尼力受工作电流实时可控,同时还具有输出阻力大、动态范围宽、响应速度快、低功耗等优良特性,为研究自动武器发射时的冲击缓冲及振动稳定性问题带来了新的机遇和挑战。将磁流变阻尼器用于武器系统的冲击缓冲装置中,建立后坐阻力闭环控制系统,期望能够对后坐阻力规律和后坐运动进行更好的控制,从而提高武器发射精度,保证发射时的静止性、稳定性,满足对架体载荷和后坐长度的要求。本文以武器系统冲击缓冲为应用背景,采用理论分析,仿真设计,试验验证的方法,深入研究了冲击载荷下,磁流变阻尼器的动态特性及其后坐缓冲控制系统,主要内容及创新之处如下:(1)对冲击载荷下磁流变阻尼器的动态特性进行了研究。通过非线性最小二乘法对试验数据拟合得到:基于Herschel-Bulkley非线性磁流变液本构特性的平行平板恒流模型能够准确描述冲击载荷下后坐过程速度下降阶段磁流变阻尼器的动态特性。针对以上模型在高低速时函数表达不同且形式复杂的缺点,采用双曲正切函数描述低速时阻尼力随速度的平滑下降特性,提出了一种形式统一、表达简洁的磁流变阻尼器动态模型,并对模型进行了参数辨识。通过对冲击后坐过程的数值仿真,证明了以上简化模型的正确性。(2)对磁流变阻尼器在冲击缓冲应用中的可控性进行分析得到:磁流变阻尼器后坐速度峰值由冲击载荷的能量决定,相同冲击载荷下控制电流对磁流变阻尼器后坐速度峰值影响很小;对后坐运动的控制区为后坐速度峰值过后的速度下降区域。(3)对磁流变阻尼器的动态响应时间进行了研究。通过对电磁回路的理论分析和试验测试得到,磁流变阻尼器线圈电磁回路中电流的响应时间是磁流变阻尼器响应时间不理想的主要因素。通过对电磁回路的设计校正,改善了电磁回路中电流响应的动态性能,缩短了磁流变阻尼器的响应时间,对于几百毫秒的后坐控制过程,该研究解决了冲击缓冲应用中磁流变阻尼器响应时间过慢的问题。(4)对磁流变阻尼器后坐控制系统进行了研究。对于系统的非线性,采用逆系统方法加以解决,并对反馈线性化的伪线性系统进行了PI校正;考虑控制系统简化建模引起的未建模动态,以及控制系统参数的不确定性,并针对后坐过程迅速的特点,采用模型参考自适应控制加以解决。通过后坐缓冲试验测试得到:在相同的后坐行程下,运用PI校正和自适应控制方法均能实现对后坐阻力峰值的有效控制,使后坐阻力曲线达到良好的充满度,后坐动态特性令人满意。两种控制方法相比,自适应控制方法比PI校正更为有效。以上结论证明了磁流变阻尼器后坐控制系统设计方法的有效性。(5)对冲击载荷下磁流变阻尼器的结构优化设计方法进行了研究。提出了冲击缓冲应用中,对磁流变阻尼器的性能要求及设计指标,并采用基于Herschel-Bulkley磁流变液本构特性的平行平板恒流模型,运用多目标规划方法,对磁流变阻尼器进行了优化设计。更多还原

【Abstract】 When firing, the artillery will experience severely impact load, yielding by the high temperature and high pressure powder gas, and vibrations and beats occurs which will decrease the firing precision and stability. Although most weapon systems already have a passive recoil mechanism, the desire for building lighter weapons with increased firing power and more mission flexibility have placed new demands on the recoil mechanicsms that cannot be met with the traditional passive systems.With the development of smart material science, Magneto-rheological(MR) dampers, whose damping force can be controlled by the current applied in the damper coils, are preferd for its large output damping force, wide dynamic range, rapid response and low power supply, which have brought out new challenges for development of the recoil mechanisms and the vibration stability control of weapons.For recoil mechanisms applications, MR dampers are desired to provide optimal damping force to control the recoil dynamics, so that large peak of recoil forces can be avoided with a certain limited stroke, and the firing stillness and stability are ensured. In this dissertation, on the background of the recoil mechanisms applications, the dynamic performance of MR damper and its control system under impact load are investigated in depth. The main contributions of this dissertation are as follows:(1) The dynamic performance of the MR damper under impact is studied. By fitting the experimental data with nonlinear least square method, it’s shown that the steady flow equations for parallel plates based on the non-linear Herschel-Bulkley fluid model are able to accurately describe the dynamic behavior of the MR damper under impact load, at the decreasing stage of the recoil velocities. Since the mathematical expression of the above model is complicated with different forms in high and low velocities respectively, a simplified model with uniform expression is put forward and parameters of the model are identified. The validy of the simplified model is verified by numerical simulation of the recoil cycle.(2) The controllability of MR dampers for recoil mechanisms applications is analyzed and it’s concluded that the applied current of MR dampers have little effect on the peak of the recoil velocities which is decided by the amount of the imact energy, and during recoil the control region of MR dampers is at the decreasing stage of the recoil velocities. (3) The response time of the MR damper is investigated by analysis of the magnetic circuit and test of the MR damper. The results indicate that the response time of MR dampers is mainly due to the current reponse time of the magnetic circuit. By modification of the magnetic circuit, the MR damper’s response time can be shortened, and the limit of the MR damper’s response time for recoil mechanisms applications is solved.(4) The MR damper recoil control system is investigated. For the nonlinear characteristics, inverse system method based on the thought of feedback linearization is used, and the pseudolinear system is modified by PI controller. Considering the dynamic behavior ignored during simplified modeling and the uncertainty of the control system parameters, model reference adaptive control method is adopted. It’s shown by test, that with the same recoil stroke, large peak of the recoil force is avoided and the ideal recoil dynamics is achieved by using PI controller or the adaptive control method. The validity of the MR damper recoil control system is verified, and compared with the PI controller the adaptive control method is more effective.(5) The optimal design method of MR dampers for recoil applications is discussed. The performance reqirements of MR dampers are proposed, and the optimal design of MR dampers for recoil applications is put forward by using multi-objective planning method, with parallel plates model based on the hurschel bulkley MR fluid characteristic.更多还原