空间环境下SMA驱动器概率设计理论与方法

Non-explosive release technology used in the aerospace application, different from the traditional explosive release technology, possesses the advantages of low shock, no contamination and resettable, which is well suited for precision equipment used in aerospace crafts, and plays a key role in the space and defense related science and technology. SMA (Shape Memory Alloy) actuator design theory is the core of SMA-based non-explosive release technology, which is a basic theory and needs to be further developed. Considering that current SMA constitutive models can not describe some behaviors of SMAs under aerospace operation conditions, this project plans to study the influences of high heating rate and over-heating working conditions on SMA performances, and established a SMA constitutive model which is suitable for aerospace operation conditions under general thermodynamic framework. Moreover, motivated by the fact that exist SMA actuator design theories can not address the inherent uncertainties involved in material prosperities, manufacturing and operation conditions related with SMA actuators, this project also plans to study these inherent uncertainties and establish probability models to describe their probability distributions. Based on these probability models, the aforementioned SMA constitutive model and specific structures of SMA actuators, following the stress-strength interference concept, a probabilistic design theory for aerospace-used SMA actuator will be finally established. In summary, this project can establish an aerospace-used SMA constitutive model and a probabilistic SMA actuator design theory, which will make an important theoretic foundation for the progress of non-explosive release technology in China.

航天非火工释放技术和传统利用火药爆炸能量的火工释放技术相比，具有冲击小、无烟尘污染、可重复使用等优点，非常适合用于对冲击和烟尘污染敏感的精密设备中，对我国的航天、国防科技具有重要意义。形状记忆合金（SMA，shape memory alloy）驱动器设计理论是SMA非火工释放技术的核心，本项目拟针对当前SMA本构模型不适用于航天特殊环境的问题，探究高加热速率和过加热等对SMA性能的影响规律，建立适用于航天特殊环境的SMA本构模型；针对现有SMA驱动器设计理论不能考虑材料、制造、使用等环节中随机因素影响的不足，系统研究影响SMA驱动器可靠性的随机因素及其分布规律，利用发展的SMA本构模型，结合驱动器的具体结构形式，基于应力强度干涉原理，建立SMA驱动器概率设计理论。通过本项目的研究，可建立航天特殊环境SMA本构模型和SMA驱动器概率设计理论，为我国航天非火工释放技术的进步奠定重要的理论基础。

形状记忆合金（SMA，shape memory alloy）驱动器设计理论是形状记忆合金非火工释放技术的核心，对我国的空间科学研究和国防科技都具有重要的意义。本项目围绕发展航天非火工SMA驱动器概率设计理论与方法的目标，从材料试验研究、本构模型构建、驱动器概率设计方法探索和工程应用样机研制四个层面开展了研究，在基础理论及工程应用层面均取得了突破性进展，重要研究结果如下：.1）不同加热速率下Ni49.8Ti50.2 (at.%)形状记忆合金丝疲劳寿命试验表明，最高温度Thigh和疲劳寿命Nf在半对数坐标系下服从线性递减规律，斜率为Thigh /log(Nf)= 68.03℃；当Thigh≤115℃时，塑性应变随着循环次数的增加会逐渐稳定，当Thigh<211℃时，可回复应变随着循环次数增加而减小，当Thigh>211℃时，可回复应变不发生明显衰减。.2）在广义热力学框架下推导了描述塑性应变、最大相变应变演化控制方程，从而建立了能够描述SMA丝材功能衰减的本构模型，并将模型计算结果和试验结果进行了对比，验证了模型描述的精确性。.3）开展了限位模式、加热电流、加热时间、SMA丝安装长度和负载对SMA丝驱动器的影响规律研究，最终确定了最优的参数，并在最优参数下开展了输出位移的概率特性研究，结果表明在0.99999065533可靠度下，SMA驱动器可保证在40次内输出位移大于0.98mm。.4）针对空间飞行器对非火工大载荷锁紧释放装置的需求，提出了基于分组滚棒减摩擦原理的大载荷SMA锁紧释放机构设计方案，开展了可靠性设计、驱动模块设计、原理样机制造及性能测试等工作。试验结果表明，研制机构具有释放载荷大、可靠性高等特点，在空间飞行器锁紧释放领域具有巨大的应用潜力。