高速齿轮轴系由于不平衡量等因素受陀螺效应会产生较大弯矩存在潜在共振危险,计及转轴及齿轮轮体陀螺效应,分别采用梁单元法和有限元法建立某型共轴高速直升机传动系统高速输入轴系模型,系统研究高速齿轮轴系不同振型的涡动现象,结合临界转速坎贝尔图,对比自由与约束模态和约束模态下不同轴承刚度对临界转速数值影响.结果表明:高速齿轮轴系扭转和伸缩振型在自由及约束模态均不会产生涡动,弯曲、节径等横向振型产生明显涡动现象,且在约束模态下涡动现象减弱;临界转速数值随约束模态轴承刚度增加呈增大趋势.在高速齿轮轴系临界转速准确计算中,轴承刚度及陀螺效应影响不可忽视.

对于新研制的直升机传动轴系，设计阶段通常要进行多种方案对比与影响参数分析，以获得相对较优的设计方案，但采用有限元法计算工作量较大、计算效率偏低，亟需一种快速且精确的直升机传动轴临界转速分析方法。以某直升机尾斜轴为研究对象，建立了综合考虑弯矩、横向位移、剪切变形、转动惯量、陀螺力矩和轴向力等因素影响的尾传动轴临界转速的计算模型，推导出临界转速计算公式。通过对比多种分析模型的计算结果，获得了各个影响因素对直升机尾传动轴临界转速的影响规律，并给出了选用直升机尾传动轴临界转速分析方法的建议。

直升机传动系统旋翼轴系振动是影响其运行可靠性的重要因素,为了提高某共轴反转双旋翼传动系统旋翼轴系扭振安全裕度,在考虑轻量化设计的前提下,通过改变轴段直径尺寸或改变激励频率,使得扭振固有频率与激励频率错开,达到避免共振的目的,实现了轴系扭振调频的优化设计.优化后的轴系扭振安全裕度达到10％以上,扭振特性得到了有效改善.其计算与优化方法对直升机传动系统旋翼轴系的改进设计具有一定的指导意义.

采用正弦激励对某直升机全尺寸的尾传动轴系进行振动试验,研究了其等效固有频率和阻尼比随激励水平的变化规律;通过不同激励水平正弦扫频试验,获取尾传动轴系的频响函数;基于频响函数辨识等效固有频率和阻尼比随激励水平的变化关系.试验表明:随着激励水平的增大,尾传动轴系的等效固有频率随着位移水平逐渐增大,呈现刚度渐硬的非线性刚度特征;而等效阻尼比则随着速度水平逐渐减小,呈现阻尼非线性特征.该试验方法对于直升机尾传动轴系的动力学设计优化具有重要意义.

共轴刚性旋翼高速直升机由共轴反转的两幅旋翼实现悬停和爬升,由尾推进桨实现高速前飞,旋翼不需要倾转,相对倾转式旋翼机可靠性更高,具有较好的发展前景.共轴反转传动系统是共轴刚性旋翼高速直升机的关键传动部件.本文分析了共轴反转传动系统构型原理;针对共轴反转输出功能需求,将共轴反转传动系统分为以圆柱齿轮为基础、以锥齿轮为基础、以面齿轮为基础和以差动轮系为基础实现共轴反转输出的4类传动系统构型.分别论述了4类共轴反转传动系统构型的国内外发展现状、主要特点和型号应用情况,为不同需求共轴式直升机的传动系统构型选型设计提供参考.

针对传统故障诊断中提取的特征不具有自适应能力、很难匹配特定故障的问题,提出了一种基于连续小波变换(CWT)和二维卷积神经网络(CNN)的齿轮箱故障诊断方法.该方法对齿轮箱故障振动信号采用连续小波变换构造其时频图,以其为输入构建卷积神经网络模型,通过多层卷积池化形成深层分布式故障特征表达.利用反向传播算法调整网络各层的结构参数,使模型建立从信号特征到故障状态之间的准确映射.在不同工况和不同故障状态下的实验中,故障识别准确率达到了99.2％,验证了方法有效性.采用这种自适应学习信号中丰富的信息的方法,可以为故障诊断智能化提供基础.

提出了一种基于频响函数识别结构非线性模态参数的方法,利用线性的模态分析技术,结合响应幅值线性化理论,通过步进正弦扫频测试激励非线性结构,得到结构在不同激励水平下的频响函数信息,最终识别得到非线性模态参数:包括与位移幅值相关的固有频率、与速度幅值相关的阻尼比.通过单自由度非线性系统与线性系统的对比,验证该方法的可行性.通过提取系统的非线性等效刚度、阻尼函数,与谐波平衡法的结果进行对比,验证该方法识别的准确性.

提出了基于测试数据来识别尾传动轴系非线性刚度参数的方法.首先,对尾传动轴系进行低幅值激励下的模态测试,并建立尾传动轴系的简化模型,与试验结果对比验证模型的准确性.然后,对尾传动轴系开展不同激励水平下的步进正弦扫频测试,基于测试频响函数得到固有频率随位移幅值的变化关系.对建立的尾传动轴系简化模型进行有限元迭代计算,可以识别出固有频率随等效刚度的变化关系.最终建立起尾传动轴系等效刚度与位移幅值的关系,识别出尾传动轴系的非线性刚度参数.

提出了基于测试频响函数识别尾传动轴系非线性模态参数的方法.利用线性的模态分析技术,并结合响应幅值线性化理论,通过步进正弦扫频测试激励尾传动轴系,得到直升机尾传动轴系不同激励水平下的频响函数信息,最终识别出尾传动轴系的非线性模态参数.分析结果表明:随着激励力幅值的增大,尾传动轴系的一阶固有频率减小约2％,而阻尼比增大约1.5倍,且在同一状态下多组试验分析结果一致.提出的识别尾传动轴系非线性模态参数的方法,为进一步精确研究直升机尾传动轴系的动力学特性奠定了基础.

基于传动效率直接、间接测试法测试原理,开展了某型直升机主减速器传动效率试验研究,对比分析了不同工况下传动效率变化规律.试验结果表明:主减速器传动效率与输入扭矩、滑油温度成正相关,与输入转速成负相关,在小扭矩状态下变化明显,且其随转速的变化率明显小于随扭矩的变化率;同时各工况下传动效率的间接测试结果均大于直接测试结果,随着输入扭矩的增加,间接测试与直接测试传动效率相对差值逐渐减小,而两者之差随转速变化不明显.误差分析结果表明:各工况下,采用间接测试法的测试极限误差均小于直接测试法,直接、间接测试法最大测试误差分别为1.28％、0.72％.

All translational motion components of a helicopter and position parameters of its tail drive shaft do not affect critical speeds of its tail drive shaft,and only rotating motion components of the helicopter affect critical speeds of its tail drive shaft.The influences of rotating motion components of a helicopter on critical speeds of its tail drive shaft were analyzed.The results showed that the yaw angular velocity versus the critical speed of the horizontal drive shaft reveals a relation of parabola,while the yaw angular velocity versus the critical speed of the oblique tail drive shaft is a linear relation and the relation curve is symmetrical;the symmetry axis offsets to the left with increase in the inclination angle of the oblique tail drive shaft;the influence of the pitching angular velocity on critical speeds of the tail drive shaft is the same as that of the yaw angular velocity;the relations'between the rolling angular velocity and critical speeds of the horizontal drive shaft and the oblique tail drive shaft are a linear relation,and the symmetry axis offsets to the right with increase in the inclination angle of the oblique tail drive shaft;the angular velocity corresponding to the symmetric axis of the second-order critical speed curve of the drive shaft is about 16 times of the first-order critical speed.

以直升机尾斜轴为研究对象,推导了传动轴的分布质量传递矩阵,模型中考虑了弯矩、横向位移、剪切变形、转动惯量、陀螺力矩和轴向力等因素的综合影响.建立了膜片联轴器和弹性支承的传递矩阵.给出了尾传动轴系临界转速的计算方法.以三支点水平轴系为分析对象,将本文传递矩阵法计算的结果与有限元法计算的结果进行了对比分析,以检验本文传递矩阵法的有效性.本文传递矩阵法相对于有限元法的最大计算误差为4.1％,表明本文传递矩阵法的计算精度较高,同时本文传递矩阵法的计算速度更快,便于设计人员进行尾传动轴系临界转速的影响因素分析.

建立了具有普遍性的考虑直升机空间机动飞行的尾传动轴动力学模型.分析了机动飞行对尾传动轴临界转速的影响,发现只有俯仰角速度、偏航角速度、横滚角速度和角加速度4个转动运动分量会影响尾传动轴的临界转速.通过算例着重分析了俯仰、偏航和横滚角速度对尾传动轴前3阶临界转速的影响规律.结果表明:俯仰角速度使尾传动轴的临界转速降低,但只对反进动第1阶临界转速有较大影响;偏航角速度对尾传动轴临界转速的影响效果与俯仰角速度完全相同;正向横滚角速度使尾传动轴的正进动临界转速提高,而使反进动临界转速降低;但对于反向横滚,在以横滚角速度等于某值的分界线之前,横滚角速度对尾传动轴临界转速的影响规律与正向横滚相反,前3阶临界转速变化曲线的分界线对应的横滚角速度分别为1.86,27.41,124.5 rad/s.

Based on finite element method, the contact property of groove bal bearing is analyzed, the contact stress, contact deformation, radial deformation and relative slip distributions of groove bal bearing are obtained, and the reliability of computa-tion result obtained by finite element method is proved, compared with the Hertz theory. The influence of load and friction coeffi-cient on the contact characteristics of bal bearings is analyzed. The results show that the contact stress, contact deformation, radial deformation and relative slip of the bearing increase with the increase of load, but decrease with the increase of friction coefficient.

A design method for system parameters of a smart spring system with linear viscous damping under harmonic excitation was presented,it could make the smart spring system implement both stiffness and damping control. Firstly,the analytical solutions to the frequency response characteristics of the smart spring system were deduced with the equivalent linearization method.Then,the influence of the system parameters on the amplitude frequency characteristics of the system was analyzed.The results showed that the amplitude frequency characteristic curve cluster has a common point for the smart spring system without viscous damping,but the common point disappears for the system with damping;the main parameters affecting the amplitude frequency characteristics of the system are mass ratio,stiffness ratio,damping ratio and control parameter;the system parameters affecting the magnitude of required actuator force to make two mass-spring systems become fully coupled are damping ratio and relative damping ratio.Based on the conclusions of the above parametric analysis,the selection scopes of the system parameters of the smart spring system were determined and the steps of parametric design were proposed.

A description method for spatial motions of helicopter maneuver flight and helicopter tail drive shaft was proposed and the corresponding coordinate systems were established.A lateral bending vibration model of the helicopter oblique tail drive shaft during maneuvering flight was established by using the extended Hamilton's principle,and the partial differential equations were converted into the ordinary differential ones by using Galerkin method.A horizontal shaft could be regarded as a special case of an oblique tail shaft,and the dynamic equations of the oblique tail drive shaft could be converted into those of a horizontal drive shaft by using a coordinate transformation matrix.The effects of spatial maneuver flight on the vibration characteristics of the tail drive shaft were discussed with the combination of mathematical model and numerical simulation.The study results revealed that the spatial maneuver flight of a helicopter can produce additional stiffness effect,damping effect and external excitation force effect on the bending vibration of the helicopter tail drive shoft,they may change the center position and the size of the motion orbit of the tail drive shaft.

The objective of this work was to study the vibration transmissibility characteristics of the undamped and damped smart spring systems. The frequency response characteristics of them were analyzed by using the equivalent linearization technique, and the possible types of the system motion were distinguished by using the starting and ending frequencies. The influences of system parameters on the vibration transmissibility characteristics were discussed. The following conclusions may be drawn from the analysis results. The undamped smart spring system may simultaneously have one starting frequency and one ending frequency or only have one starting frequency, and the damped system may simultaneously have two starting frequencies and one ending frequency. There is an optimal control parameter to make the peak value of the vibration transmissibility curve of the system be minimum. When the mass ratio is far away from the stiffness ratio, the vibration transmissibility is small. The effect of the damping ratio on the system vibration transmissibility is significant while the control parameter is less than its optimal value. But the influence of the relative damping ratio on the vibration transmissibility is small.

研究了无阻尼智能弹簧减振系统的一种参数设计方法.采用等效线性化方法将系统中的干摩擦阻尼等效成黏性阻尼,建立系统的数学模型,推导出无量纲化的振动微分方程,得到系统频响特性的解析解.对系统幅频特性进行了数值分析,结果发现:幅频特性曲线簇通过一个公共点,该公共点随质量比的增大向左偏移,随刚度比的增大向右偏移;系统存在一个最优控制参数值,使系统幅频特性曲线峰值最小,其随质量比的增大而减小,但不受刚度比的影响.根据公共点的性质,得到幅频特性曲线簇公共点对应的频率比、最优控制参数和最小振幅的计算公式.确定系统参数的选用原则与范围,并利用公共点提出智能弹簧减振系统参数设计的方法和步骤.

A piecewise parabolic function of involute spline couplings axial modification was presented, and the modified geometric model of involute spline couplings was built. Based on the finite element method, the fretting frictional contact property of typical involute spline couplings was analyzed, and the contact stress and relative slip distributions of modified and unmodified involute spline couplings were obtained, as well as the effects of modified position and modified quantity on contact characteristics of modified involute spline couplings were considered. The following conclusions can be drawn from the analysis results. The piecewise parabolic function meets the axial modification requirement of involute spline couplings, and the modification curve is smooth. Axial modification can effectively reduce phenomena of concentrated contact stress and relative slip for involute spline. Modified positions should be the ends and latter half of external spline in the typical model. Modification quantity of the ends should be a reasonable choice for the model, and modification quantity of the back is generally larger than that of the front.

The model of negative vibration isolation system based on the smart spring was established.The non-smooth system caused by dry friction was proposed to be piecewise linear,so that the analytical solution of system response could be solved by using connected-seam method.The possible response pattern of the system was studied.By numeric simulation,the motion characteristics varying with the operating frequency,near the slip-starting frequency,for a set of structural parameters,were analyzed.The following conclusions are drawn from the analysis result.A rather great distorsion happens on the response curve of the vibration isolation system in the slip region,and is of rich motion features,including the arising of single-period response,multi-period sub-harmonic response,super-harmonic response,qusi-periodic and chaotic response in the system.The system tends to maintain sticking motion outside the slipping region,as a result,the primary spring and the active spring can be looked as rigidly coupling to a single degree of freedom system.So there are two kinds of motion status in the system,the multi-period and the aperiodic response.The vibration isolation system based on the smart spring mechanism(SSM) can be used to suppress the vibration transmission in an adaptive manner by controlling the piezoelectric actuator voltage in order to vary both the stiffness and damping of the system.