Sun Xiuting, Xu Jian, Qi Zhifeng
School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China.
Fundam Res. 2022 Aug 6;4(6):1613-1624. doi: 10.1016/j.fmre.2022.06.023. eCollection 2024 Nov.
By the biological construction of a bird neck, a bionic bird-neck multilevel rigid-flexible structure is proposed and some biometric properties are explained. The proposed structure can flexibly deform in six directions, which inspires the study of its mechanical properties for flexible deformations. First, the structural configuration and composition are determined based on the study of the anatomical characteristics of the woodpeckers. Since the skeletons and muscles have very different values for the elasticity modulus and the deformation is mostly dependent on the muscle tension, the bionic structure consists of rigid units and bio-syncretic components. For combined deformations, the mechanical model is established by the connectivity matrix to describe the connection of each level. Second, based on the principle of minimum potential energy, an integral form-finding method is proposed for flexible combination deformations. All of the integral forms obtained with the theoretical analysis are compared with the results with Finite Element Analysis. The structural parameters of the bionic structure were then tightly fixed to the actual shape of the bird's neck and the corresponding overall form took on an "S" shape, which perfectly matched the construction of the bird's neck. In addition, for the pre-deformation form, by analyzing the potential energy of the bionic structure, due to the adjustable dynamic stiffness property, an explanation is provided for the significant dynamic stability of the bird neck in bending. This study not only proposes a bionic rigid-flexible structure with high spatial accessibility but also explains biological properties of a bird neck based on the study of its mechanics characteristics. Based on the modeling and the mechanical properties of the bionic structure in flexible spatial combination deformations, the multi-steady state, and the variable dynamic stiffness, the bird-neck bionic rigid-flexible structure has significant applications such as aeronautical deployable systems, manipulator positioning, and dynamic stability fields.
通过对鸟类颈部的生物构造研究，提出了一种仿生鸟颈多级刚柔结构，并对其一些生物特征属性进行了解释。所提出的结构能够在六个方向上灵活变形，这激发了对其柔性变形力学性能的研究。首先，基于对啄木鸟解剖特征的研究确定结构构型和组成。由于骨骼和肌肉的弹性模量值差异很大，且变形主要取决于肌肉张力，因此仿生结构由刚性单元和生物融合组件组成。对于组合变形，通过连通性矩阵建立力学模型来描述各层级之间的连接。其次，基于最小势能原理，提出了一种用于柔性组合变形的整体找形方法。将理论分析得到的所有整体形式与有限元分析结果进行比较。然后将仿生结构的结构参数紧密固定到鸟类颈部的实际形状上，相应的整体形状呈现出“S”形，与鸟类颈部的构造完美匹配。此外，对于预变形形式，通过分析仿生结构的势能，由于其具有可调节的动态刚度特性，对鸟类颈部在弯曲时具有显著动态稳定性给出了解释。本研究不仅提出了一种具有高空间可达性的仿生刚柔结构，还基于对其力学特性的研究解释了鸟类颈部的生物学特性。基于仿生结构在柔性空间组合变形、多稳态和可变动态刚度方面的建模及力学性能，鸟颈仿生刚柔结构在航空可展开系统、机械手定位和动态稳定性领域等具有重要应用。
