摘要：在热处理航空制件的过程中,热处理炉温度的均匀性对其质量与性能具有直接影响.以大尺寸燃气热处理炉为研究对象,先采用热电偶测试测得在不同工作温度下的热处理炉温度均匀性指标,然后基于热处理炉的具体尺寸和运行参数,采用Fluent软件进行数值模拟,得到热处理炉全场的温度分布情况,最后通过调节烧嘴与壁面的夹角,对典型工况下全场温度的均匀性进行优化.结果表明:该航空制件燃气热处理炉的上层温度在各保温时刻较为稳定,且随着保温温度的升高,热处理炉各段炉温的均匀性均得到明显改善;温度场的仿真模拟值与现场实测值相差较小,该有限元模型较为可靠.本研究结果可为热处理炉温度均匀性的改进设计提供一定的理论参考.

摘要：Improving structures involves comparing old and new designs on a key *** the percent change in performance is a method to *** paper proposes a cost-effective analogy by generating replicas of additive manufactured aluminum alloy(Al Si10Mg)body-centered cubic lattice(BCC)based turbine blade(T106C)with the same in poly-lactic acid(PLA)material and their comparison in the context of percent change for natural ***,a cavity is created inside the turbine blade(hollow blade).Natural frequencies are obtained experimentally and numerically by incorporating BCC at 50%and 80%of the cavity length into the hollow blade for both *** cost of manufacturing the metal blades is 90%more than that of the PLA *** two material blade designs show a similar percentage variation,as the first-order mode enhancs more than 5%and the second-order mode more than 4%.To observe the behavior in another material,both blades are analyzed numerically with a nickel-based U-500 material,and the same result is achieved,describing that percent change between designs can be verified using the PLA material.

摘要：针对大跨度斜拉桥边墩的横向抗震问题,提出桥梁新型横向钢阻尼器与滑动支座组合的一种边墩横向减震体系,以及基于桥梁实际抗震需求的减震体系设计方法。之后,以一座主跨620m的大跨度斜拉桥为工程背景,验证该方法的可行性。并从关键位置的地震反应、阻尼器对横向基本控制振型的影响、减震体系的耗能能力和地震动输入的影响等方面对边墩新型横向减震体系的减震效果进行全面分析。结果表明,大跨度斜拉桥边墩新型减震体系具有显著的减震效果;与常规体系相比,对地震动输入较不敏感。

摘要：In cryogenic wind tunnel tests,piezoelectric stacks are adopted to realize the vibration control of the cantilever ***,the free stroke and blocking force of the piezoelectric stack would decrease dramatically as the temperature *** paper proposes a convenient and effective warming structure for the piezoelectric stack,which could keep it working at operating temperatures when the ambient temperature *** piezoelectric stack actuator is wrapped with the heating film,and this resulting assembly is then wrapped with the aerogel material for thermal *** ends of the piezoelectric stack actuator make direct contact with the payload *** one-dimensional and two-dimensional theoretical analyses of the heating conduction problem of the piezoelectric stack actuator are *** analyses results are compared with those of the finite element simulation *** finite element method results show a good consistency with the two-dimensional theoretical results,and a slight deviation of only 0.91 K is observed,indicating its potential for protecting piezoelectric stacks at low temperatures.

摘要：运载火箭在发射过程中会经历复杂的动力学环境,而普通的隔振器无法做到对高频冲击振动进行抑制的同时避免对低频振动的放大。利用形状记忆合金(SMA)作为驱动器,结合金属橡胶的刚度对形变量敏感的特点,设计了一种可改变自身固有频率的隔振器。在实验研究不同参数的金属橡胶隔振特性的基础之上,选用合适的金属橡胶作为可变频隔振器的隔振元件,并通过实验对比隔振器变频前后的共振频率差异。实验结果表明,所设计的可变频隔振器的固有频率从60 Hz以下提高到110 Hz以上,满足设计要求。

摘要：In wind tunnel tests,long cantilever stings are usually used to support aerodynamic ***,this kind of sting support system is prone to vibration problems due to its low damping,which limits the test envelope and affects the data *** is shown in many studies that the sting vibration can be effectively reduced by using active sting dampers based on piezoelectric *** paper attempts to review the research progress of piezoelectric vibration control in wind tunnel tests,covering the design of active sting dampers,control methods and wind tunnel *** of all,different design schemes of active sting dampers are briefly introduced,along with the vibration damping ***,a comprehensive review of the control methods for active sting dampers is presented,ranging from classic control methods,like PID control algorithm,to various intelligent control ***,the applications of active sting dampers and controllers in different wind tunnels are summarized to evaluate their vibration damping ***,the remaining problems that need to be solved in the future development of piezoelectric vibration control in wind tunnel tests are discussed.

摘要：变体飞行器的结构既需要改变气动外形,也需要传递载荷。针对一种变体翼尖的设计需要,使用能量方法,构建了等效力学模型。在实现对波纹板刚度特性等效替代的同时,获得了波纹板整体应变与结构内局部应变的转换关系,从而可以通过对波纹板局部材料进行失效判定,实现对波纹板整体失效应变的预测;经过实验验证,该等效力学模型的解析解与实验值相比平均误差在10%以内。通过对波纹板几何尺寸进行参数分析,获得了单元几何参数对波纹板失效应变和等效刚度的影响关系。最终,针对变体飞行器承载与变形的设计需要,对波纹板进行了优化设计,进一步评估了波纹板结构的强度与刚度特性,为变体翼尖的设计提供了依据。

摘要：首先基于压电陶瓷变压器PT(Piezoelectric transformer)设计了一种用于驱动压电材料作动器的功率放大器,该放大器具有效率高、体积小、重量轻等优点。与DSP控制系统相结合,实现了振动主动控制系统的小型化和集成化。然后以飞机垂直尾翼模型为控制对象,选用了压电纤维复合材料(Micro fiber composites,MFC)和(Piezoelectric transducer,PZT)作为驱动器,实现了对模型两阶主要振动模态的主动控制。实验验证了所设计的开关功率放大器的可行性,最后对MFC和PZT的驱动性能进行了对比。

摘要：无人机的重量分析一直是无人机初步设计中一个重要的环节。本文通过对无人机结构重量数据的统计,结合专家设计经验及工程实践推导出无人机结构重量估算公式。用此公式对某型高空长航时无人机结构重量进行计算,分析表明此公式可以用来对初步设计阶段的无人机结构重量进行估算,合理且可靠。在此公式的基础上,推导出各个参数对结构重量的影响,对无人机的设计参数对无人机结构重量的影响进行了分析,得到了较好的结果。在无人机设计中,应着重考虑这些参数的影响,并尽量考虑到其他因素的存在。

摘要：Intelligent structures like zero Poisson’s ratio(ZPR)cellular structures have been widely applied to the engineering fields such as morphing wings in recent decades,owing to their outstanding characteristics including light weight and low effective modulus. In-plane and out-of-plane mechanical properties of ZPR cellular structures are investigated in this paper. A theoretical method for calculating in-plane tensile modulus,in-plane shear modulus and out-of-plane bending modulus of ZPR cellular structures is proposed,and the impacts of the unit cell geometrical configurations on in-plane tensile modulus,in-plane shear modulus and out-of-plane bending modulus are studied systematically based on finite element(FE)simulation. Experimental tests validate the feasibility and effectiveness of the theoretical and FE analysis. And the results show that the in-plane and out-of-plane mechanical properties of ZPR cellular structures can be manipulated by designing cell geometrical parameters.