In aerospace engineering, electronic equipment is always connected to the cabin via connection brackets, which often exhibit a notable amplifying effect on the vibration signals transmitted from the cabin. To guarantee the normal operation of electronic equipment, it is essential to investigate the vibration and shock response of these connection brackets in the harsh environment of aerospace engineering. Currently, the most commonly used connection brackets are fabricated using aluminum alloy through the sheet metal process. This paper compares the random vibration and shock response of the connected brackets made of different materials through both experimental and numerical methods, and further investigates the effects of different structural configurations on their dynamic responses. The objective is to mitigate the vibration response of the connection brackets in high-frequency random vibration environments and high-magnitude impact environments. Experimental results indicate that brackets fabricated with sandwich materials exhibited the lowest response measured in both random and shock vibration environments. Additionally, numerical results show that the box-shaped structural form obtained the lowest measured vibration response. This provides new insights and data to support the optimization and design of connection brackets for electronic equipment in aerospace engineering.

目的 研究提出基于分档策略的装备统一环境试验条件设计方法 .方法 首先,对装备力、热、自然等环境试验条件的统一化进行详细论证,研究得到不同类型环境条件的分档策略.然后,对不同型号环境试验条件的项目进行分析,提出环境试验项目"基本项"+"定制项"的统一方法 ,得到通用试验项目和定制试验项目.随后,对于特定环境试验项目,提出基于极值的"包络式"、基于概率统计的"精细式"和基于就近归集的"分档式"3种统一环境试验条件制定方法 ,给出各种方法 的特点、剪裁方法 ,并结合典型航天型号,给出应用案例和方法 示意.结果 得到了基于分档策略的装备统一环境条件制定的方法 ,给出了典型装备的分档环境试验条件.结论 从装备的实际出发,提出的基于分档策略的装备统一环境试验条件的设计方法 ,经实践证明是可行的,对于降低货架产品的研制、批产和验收成本具有重要工程意义,并且对于其他类型产品的技术条件统一化具有重要的借鉴意义.

The piezoresistive pressure sensor is a widely used electronic component whose accuracy and function are strongly affected by the external mechanical environment. This paper studies the failure mode and damage boundary of piezoresistive pressure sensors under shock load. The failure mode of the pressure-sensitive elastic plate (the kernel structure of the pressure sensor) is derived based on the thin-plate theory. The damage boundary of the piezoresistive pressure sensor is obtained by analyzing the experiment and numerical simulation results, which agree well with the theoretical analysis. Results prove that the damage boundary of the piezoresistive pressure sensor is governed by the pseudo-velocity shock response spectrum (PVSRS) of the shock environment, which is about 7 m/s for the specimen in this paper. This study can provide guidelines for the adaptability design of electronic components.

航天工程中普遍采用支架进行设备的安装,但是支架对振动环境的严重放大会影响设备的工作可靠性,给飞行器飞行带来极大隐患,需要开展典型支架的动力学管控方法研究.提出面向支架动特性管控的动力学特性指标,可以全面表征仪器支架在随机振动激励下的动力学特性,并可据此构造优化目标,以对支架动力学特性进行有效管控.提出典型仪器支架的动力学管控方法,实现了将支架动特性设计融入支架结构设计流程中.针对一种典型的仪器支架开展了随机振动试验与有限元仿真分析,验证了随机振动响应预示方法的准确性,并以此为基础,对其进行了动力学管控.以某型支架为对象开展的动力学管控,将支架上相对安装基础的振动量级放大倍数从4.2降低到1.67.结果表明,提出的典型仪器支架动力学管控方法可在研制初期改善仪器支架的动力学特性,对提高飞行器可靠性和环境适应性具有重要意义.

冲击环境是火箭、导弹等航天器在其全寿命周期经历的严酷的力学环境之一,其往往会导致航天器产品发生损伤/失效,甚至引发飞行事故,己成为制约航天器飞行可靠性提升的关键因素.本文分别从理论分析、经验外推以及数值仿真、试验研究等角度,系统总结了国内外在航天产品冲击响应分析与冲击损伤/失效两个方面的研究进展,并综述分析了国内外众多学者提出的各种冲击损伤/失效评估方法在航天产品上的适用性.在此基础上,结合我国航天工程实际,为今后的相关技术发展提出了建议.

通过加强对装备环境适应性的闭环管控,避免设计方案反复,提高研制效率和装备环境适应性.在系统工程方法基础上,建立装备环境适应性闭环管控工作体系,提出闭环管控方法,包括基于流程前置的环境工程工作计划,面向流程闭环的环境适应性工作过程控制,以及全寿命周期环境适应性信息管理等内容.装备工程实践结果表明,提出的环境适应性闭环管控方法是可行的,环境适应性问题早在方案设计阶段即得到了有效解决,使环境适应性工作变被动为主动,在提高装备研制效率的同时,提升了产品的环境适应性.该方法可以有效提高装备环境适应性和研制效率,对于运载火箭、航天器、工业设备等其他类型产品的研发也有一定的借鉴意义.

The crystal oscillator is a widely used electronic component in a circuit, whose accuracy is strongly affected by the external mechanical environment. To depict the failure mechanism of the crystal oscillator, the damage boundary of this component under the shock environment is studied experimentally in this paper. Through subjecting “step-up” loads on different groups of crystal oscillators, two failure modes (frequency jumping and structural fracture) are monitored and validated. Experimental results prove that “frequency jumping” failure mode is governed by the value of the acceleration shock response spectrum (ASRS) in a certain frequency range, while the failure mode “structural fracture” is governed by the peak value of the ASRS. Through analyzing the shock response spectrum, damage boundaries are given for these two failure modes, which can provide a reference for component design and failure assessment.

胶质阻尼(Colloidal damper)是由水和布满纳米微孔的疏水材料混合而成的新型隔振材料,以胶质阻尼为工作介质即可形成胶质阻尼隔振器.该文通过准静态和动态加载试验研究了胶质阻尼的迟滞特性,分析了加载频率、振幅对迟滞曲线的影响;之后建立了包含三次非线性刚度、粘性阻尼特性和干摩擦阻尼特性的胶质阻尼隔振器力学模型,以实测动态加载迟滞曲线为基础开展了模型参数识别;最后完成了胶质阻尼隔振器的隔振性能评估.研究表明,胶质阻尼隔振器具有良好的低频隔振性能和大阻尼特性,在设备减振领域具有良好的应用前景.

为了使电磁继电器在冲击载荷作用下不容易失效,分析了电磁继电器冲击动力学响应特性和电磁继电器的冲击失效模式及控制参数,得到不同的冲击失效模式对应的失效边界.通过电磁继电器临界失效冲击试验,证实了理论分析结果.研究成果可以为航天电子设备冲击损伤/失效评估与冲击环境适应性设计提供参考.

The thermal performance of a flat plate latent heat storage unit (LHSU) consisting of parallel flat plate slabs of phase change material (PCM) was investigated with analytical techniques. The approximate analytical expressions of the heat transfer fluid (HTF) transient temperature distribution and the time wise solid-liquid PCM interface location were developed by solving the energy conservation equations and were validated by comparing the present results with fully converged numerical predictions and analytical solutions in published literature. An index of effective latent heat storage ratio, E-r, which was defined as the ratio of the actual amount of available latent thermal energy before HTF outlet temperature reaches a specified value to the total latent heat storage capacity, was proposed to evaluate the thermal performance of a LHSU. The effects of geometric parameters and the thermal conductivity of PCM (k(r)) on E-r were investigated. The results show that the analytical model is valid as the Stefan number is less than 0.15. Moreover, E-r increases with the rise of the given dimensionless HTF outlet temperature and the enhancement of k(p), and decreases linearly with the increase of HTF channel height and PCM slab thickness, with an abrupt change in the derivative of E-r at an inflection point. A dimensionless criterion was proposed to help design thermally efficient flat plate LHSU. Additionally, we found that increasing PCM mass by lengthening the PCM slab could significantly improve E-r, while thickening the PCM slab would lead to the opposite trend. This investigation provides guidelines for the optimal design of a flat plate LHSU.

航天器插装型元器件在严酷的冲击环境下容易发生损伤失效,影响航天电子设备正常工作,甚至造成飞行事故.采用冲击动力学响应分析的方法构造了插装型元器件的冲击损伤边界,并针对航天器常用的插装型元器件——SMA (Sub-Miniature-A)射频同轴连接器开展数值仿真与冲击试验,对插装型元器件的冲击损伤边界进行验证.结果 表明,当冲击环境优势频率(Dominant Frequency)低于元器件一阶固有频率时,插装型元器件冲击损伤边界为冲击环境的绝对加速度响应渐近线;当冲击环境优势频率高于元器件一阶固有频率时,插装型元器件冲击损伤边界为冲击环境的相对位移响应渐近线.研究成果可以为基于损伤等效的冲击试验条件等效技术研究与航天器环境适应性设计提供重要基础.

Aiming at reliability design for electronic devices, process neural networks are proposed to predict the temperature of electronic devices. To avoid errors caused by discrete input data fitting or difference, only discrete data is used when solving orthogonal transformation coefficients. To accelerate the learning speed of the gradient descent algorithm, a parameter- independent adaptive learning algorithm is developed. The results show that this model has better accuracy and generalization ability compared with artificial neural networks and linear regression method, and the parameter-independent adaptive learning algorithm has quicker convergence rate compared with parameter-fixed algorithm and adaptive learning algorithm.

目的 研究一种具有变阻尼特性的剪切增稠液体(STF)隔振器.方法 首先采用二氧化硅纳米颗粒和聚乙二醇200为工作介质合成剪切增稠液体,通过试验研究剪切增稠液体的流变特性.之后以剪切增稠液体为工作介质,设计一种活塞液压式减振增稠液体隔振器,建立隔振器的动力学模型,并通过数值仿真研究了该隔振器的减振性能;最后,研究剪切增稠液体隔振器隔振性能影响因素.结果 当远离共振频率时,隔振器具有小阻尼特性;在共振区附近,由于剪切增稠效应,隔振器阻尼骤然增加,实现对共振峰的有效抑制.结论 剪切增稠液隔振器可有效抑制共振峰,同时不会对高频隔振性能产生不利影响,有效解决了传统隔振器线性阻尼的固有缺点.

目前导弹武器系统的环境适应性分析方法主要是基于剖面分析的定性分析,分析结果比较依赖个人经验,某些情况下可能无法全面识别风险,并且出现反复发作的环境适应性问题.基于此,文中开展了相关研究,全面、合理地分析导弹武器系统的环境适应性,提升装备质量特性水平.提出了基于时序的武器装备环境适应性分析方法,给出了基于时序的环境要素分析方法、产品要素分析方法和基于研制流程的工程实施方法.将该方法应用于某战术导弹,发现了63项环境适应性风险,其中有3项影响成败,通过采取针对性改进措施确保了首飞和后续多发飞行试验任务连续成功.该方法可以充分暴露武器系统环境适应性风险,并且可以作为一种风险识别方法应用到试验充分性分析和测试覆盖性分析中,具有重要的工程应用和推广价值.

针对运载火箭质量变化后模态参数预示问题,提出火箭有限元模型修正以振型吻合为主的修正策略和提高模态频率预示精度的频率补偿算法.通过理论分析指出,运载火箭模型修正频率误差对飞行器质量变化的灵敏度主要取决于振型吻合程度,在有限元模型修正不能同时兼顾频率与振型时,可以适当放宽频率修正误差,确保振型的一致性,然后在利用修正模型预示质量变化后的火箭模态频率时进行误差补偿即可很大程度上消除修正误差,确保频率预示精度.通过算例研究表明:采用补偿算法可以不同程度地消除频率修正误差,而补偿效果与振型的吻合程度有直接关系,验证了提出模型的修正策略的正确性与频率补偿方法的有效性.

火箭、导弹等航天器结构安全系数是强度设计考虑的关键参数,是设计载荷与使用载荷的比值,通常考虑材料性能散差、载荷计算偏差、结构零部件的制造工艺水平和稳定性等.目前航天器结构强度校核基本沿用传统的确定性安全系数方法,这种方法简单、可靠,但是随着航天器总体设计技术的发展和国际商业航天市场竞争的白热化,结构减重需求日趋增强,对安全系数进行精细化设计成为了一个重要的研究课题.基于此,本文开展了基于结构可靠性的航天器结构安全系数设计方法研究,给出了基于应力强度干涉模型的可靠性安全系数设计方法和设计流程,提出了基于总体偏差概率设计的航天器飞行载荷变差系数确定方法,给出了基于试验和数值仿真的导弹强度变差系数工程设计方法,可实现航天器结构安全系数精细化设计、结构减重,对提升航天器总体性能和运载能力具有重要的意义.

The main cabins of hypersonic vehicles are usually designed as double-layered thick-walled structures in order to meet the requirement of heatproof and load bearing.The acoustic-vibration environment prediction of a double-layered thick-walled structure was investigated for the sake of obtaining the precise acoustic-vibration environment of the cabin.A method for identifying the damping loss factor was proposed based on the vibro-acoustic experiments,and the process of acoustic-vibration environment predication was given.The acoustic-vibration coupling environment of a hypersonic vehicle cabin,which is double-layered thick-walled,was studied using the statistical energy analysis method.The vibro-acoustic experiment was carried out,and the damping loss factor was identified based on the experimental data.The result shows that the prediction of the acoustic-vibration environment corresponds well with the experiment results.The method for structural damping loss factor identification and acoustic-vibration prediction of thick wall structures is significant for the precise environment prediction of hypersonic vehicles,and can be widely used in the areas of aviation,aerospace,ship,and automobile industry.

Based on the first-passage failure and the accumulative fatigue damage rule, the dynamic strength reliability and parameter sensitivity of an aircraft fuel pipe system under a random load is discussed in this paper. To calculate the structural dynamic strength reliability, a method which combined the random vibration spectrum analysis, dynamic strength reliability theory and the sensitivity analysis method is proposed. Using the proposed method, the dynamic strength reliability and parameter sensitivity for an aircraft fuel pipe system is carried out. Results show that the proposed method is convenient and effective for the evaluation of the dynamic strength reliability of engineering structures.

The offshore structures experience severe shock environment caused by storms, episodic waves, icebergs or supply ships. The aerospace equipment may also encounter severe shock loadings due to pyrotechnic shock. The intensive shock causes structural failures, or even results in fatal consequences on the related facilities and persons. Therefore it is important to study the response and the damage behavior of structures under shock loading. The damage boundary of a beam under shock is studied, based on the structural dynamics and the shock response spectrum analysis. The relationship between the critical real velocity and the critical pseudo velocity is investigated, and the concept of loading factor is proposed. A simple and practical rule of estimating structure fragility is developed based on the pseudo velocity shock response spectrum and the loading factor. The explicit numerical simulation of a beam under shock loading is carried out using LS-DYNA. The critical shock response spectrums as well as the loading factor of the beam is obtained. This paper has an important significance of helping structural engineers to design the offshore and aerospace equipment under shock environment.

Through natural selection, many plant organs have evolved optimal morphologies at different length scales. However, the biomechanical strategies for different plant species to optimize their organ structures remain unclear. Here, we investigate several species of aquatic macrophytes living in the same natural environment but adopting distinctly different twisting chiral morphologies. To reveal the principle of chiral growth in these plants, we performed systematic observations and measurements of morphologies, multiscale structures and mechanical properties of their slender emergent stalks or leaves. Theoretical modeling of pre-twisted beams in bending and buckling indicates that the different growth tactics of the plants can be strongly correlated with their biomechanical functions. It is shown that the twisting chirality of aquatic macrophytes can significantly improve their survivability against failure under both internal and external loads. The theoretical predictions for different chiral configurations are in excellent agreement with experimental measurements.