空天飞行器是一种兼具航空和航天功能的可完全重复使用的新型天地往返飞行器。为了实现最佳气动性能，空天飞行器在不同的飞行阶段对其气动外形要求不同，其中减小在大气层中的飞行阻力和返回再入阶段的热流密度问题是气动性能改善的关键。在大气层中通过减小头锥剖面半径并增加长度可以实现有效减阻，而再入阶段通过增大头锥剖面半径并减小长度可实现有效减小热流密度。蜜蜂腹部灵活自如地构型变化满足空天飞行器在不同飞行阶段头锥的构型设计需求。因此，本论文借鉴蜜蜂腹部的变形机理设计了变体头锥，系统地研究了变体头锥的驱动结构设计、运动性能预测分析、样机研制与实验验证及结构优化，为高性能变体头锥设计提供理论参考。通过对蜜蜂腹部的微结构观测和肌纤维调控机制研究，建立了反映蜜蜂腹部微观结构变形到宏观运动现象的模型，揭示了蜜蜂腹部以肌肉群为分布式驱动器、以节间褶为限位保护和以壳体为基础支撑的变形机理。 参考蜜蜂腹部相邻两节背板、腹板及侧板之间的肌肉分布，提出了仿蜜蜂腹部变形机理的等效驱动单元机构，并验证了等效单元机构的合理性。将等效单元机构简化为2-RPR/2-SPS并联机构，利用Pareto最优理论的多目标优化方法对其结构参数进行优化，得到了最优结构参数。在此基础上，以2-RPR/2-SPS单元机构为目标自由度，基于约束螺旋综合法对变体头锥驱动单元机构进行型综合研究，得到满足变形需求的多种分支链结构。综合考虑各种因素，确定驱动单元机构为2-RRR/2-RRS并联机构。借鉴节间褶的构型仿生设计了变体头锥传动链结构，结合驱动单元机构和蜜蜂腹部的分节结构特点设计了仿生变体头锥结构，评估了其变形能力和动力学性能。将连续碰撞模型引入转动副关节，深入分析预测了柔性杆件和关节间隙耦合作用对变体头锥的运动性能。研究表明，柔性杆件和间隙关节会引起头锥结构产生明显的振动，而柔性结构会加快振动的衰减。基于设计的仿生变体头锥模型，研制了变体头锥物理样机，并提出了一种结构优化方法，验证了优化前后头锥的变形能力和承载能力。研究表明：优化前后变体头锥均满足设计指标的需求，且优化后变体头锥的运动稳定性和承载能力得到明显改善。

Aerospace vehicle is a completely reusable new spacecraft with both aeronautics and astronautics function. In order to achieve the best aerodynamic performance, aerospace vehicle has different requirements for their aerodynamic configuration in different flight stages. It is the key to reduce the flight drag in the atmosphere and the heat flux during the return and reentry stage for improving the aerodynamic performance of aerospace vehicle, which can be effectively realized by reducing the section radius and increasing the length in the atmosphere, while in the the return and reentry stage, by increasing the section radius and reducing the length of the nose cone. The configuration of honeybee abdomen can change flexibly, which meets the configuration design requirement of the nose cone for aerospace vehicle in different flight stages. Therefore, inspired by deformation mechanism of honeybee abdomen, a morphing nose cone is designed, and its driving structure design, predictive analysis of motion performance, prototype development, experimental verification and structure optimization are systematically studied. This research could provide theoretical reference for the morphing nose cone design with high-performance.Based on the microstructure of honeybee abdomen and the regulation mechanism of the muscle fiber, a model that reflects the microstructure deformation of honeybee abdomen to its macroscopic movement is established. This model reveals the deformation mechanism of honeybee abdomen, which is distributedly drived by the muscle group, limited by the folded intersegmental membranes and supported by the cuticle.Inspired by the muscle distribution between the two adjacent terga, sterna and lateral structure of honeybee abdomen, an equivalent drive unit mechanism is proposed, and the rationality of the equivalent unit mechanism is verified. Then the equivalent unit mechanism is simplified into a 2-RPR/2-SPS parallel mechanism, and its structural parameters is optimized by the multi-objective optimization method of Pareto optimal theory to obtain the optimal structural parameters. On this basis, the 2-RPR/2-SPS unit mechanism is taken as the target degree of freedom, and then the type synthesis of the drive unit mechanism of morphing nose cone is studied by the constrained screw synthesis method. Thus a variety of branch chain structures that meet the deformation requirement are obtained. Taking various factors into consideration, the drive unit mechanism is determined to be a 2-RRR/2-RRS parallel mechanism.Furthermore, inspired by the configuration of the folded intersegmental membranes, a bionic transmission chain structure of morphing nose cone is designed. Combined with the drive unit mechanism and the segmented structure characteristics of honeybee abdomen, a bionic morphing nose cone structure is designed, and the deformability and motion accuracy are evaluated. In addition, the continuous collision model is introduced into the revolute joint, and the motion performance of morphing nose cone under the coupled effect of flexible links and joint clearance is analyzed deeply. Results show that the existence of flexible links and joint clearance can cause obvious vibration of morphing nose cone, and flexible links will accelerate the attenuation of vibration.Finally, based on the designed morphing nose cone, the prototype of morphing nose cone is manufactured, and a structural optimization method is proposed. The deformation ability and bearing capacity of the unoptimized and optimized morphing nose cone is respectively verified by experiments. The research shows that the unoptimized and optimized morphing nose cone meet the design requirement. Besides, the motion stability and bearing capacity of the optimized morphing nose cone are significantly improved.