【作者】 周萌；

【导师】 童秉纲； 尹协振； 沈钧贤；

【作者基本信息】 中国科学技术大学 ， 流体力学， 2010， 博士

【摘要】 对鱼类游动的生物力学问题进行实验研究,在科学探索和技术开发两方面都极具意义。近年来,伴随着实验手段和技术的多样化、精细化和系统化程度的提高,针对鱼类游动运动链一体化的定量化研究成为一大趋势。为此,本文基于“神经控制一肌肉主动收缩一被动变形”这一控制框架,对鲫鱼的形态学、肌电信号以及皮肤、肌肉和躯干力学性能及本构关系进行了实验研究,并在此基础上归纳总结出“数字鱼”的简化模型,进行了如下主要工作：一、对鲫鱼样本个体以及不同样本构成的鲫鱼群体,对几何形态参数、质量形态参数方面的规律进行了实验研究：通过对不同鲫鱼样本的二维形貌记录,确定了其身体各部位,如头长、躯干长、全长等变量和体长的线性对应关系；通过影栅云纹法和三维坐标机直接测量法的定量测量及其结果的对比,得到了鲫鱼三维形貌的几何形态参数。采用分段切片的实验方式,研究了其躯体由头到尾的质量分布规律。通过对不同鲫鱼样本体长和体重进行统计,明确了二者之间的幂指数对应关系。二、研究了鲫鱼游动过程中的肌电测量技术,详细论述了肌电实验的手术操作过程,经过成年男性心电信号测量实验的标定和检验,利用自行设计制作的肌电放大器对鲫鱼在C形快速起动状态下转弯侧体表红肌的肌电信号给出了初步的测量结果,得到了其转弯侧体表红肌几乎同时开始活动、其持续的活动时间大致相同、并远小于鱼体完成整个运动历程所需时间的结论；通过前人学者就其他鱼种在巡游状态下的肌电测量实验结果来推断鲫鱼相应的结论；根据肌电活动模式,探讨了鲫鱼快速起动过程中毛氏细胞同步触发运动神经信号、产生肌肉同步收缩的神经控制方式；基于鲫鱼肌肉伸展方向与头尾轴存在夹角的结构特点,讨论其可能提供更高收缩张力的潜在助益。三、采用单轴拉伸实验的方式对鲫鱼的皮肤和肌肉分别进行了破坏实验、松弛实验和蠕变实验,以确定其杨氏模量、归一化松弛函数和归一化蠕变函数,并通过粘弹性力学模型确定其本构关系,讨论了其粘弹性性质以很小的能量损耗为代价,却增加了躯体有效刚度的可能性。采用自行设计制作的弯曲变形实验机,对鲫鱼不同部位躯干进行弯曲变形实验,以考察其角刚度和力学性能,得到了其躯干前端角刚度最大的结论；通过长时间交变加载实验的结果,获得了在动态弯曲变形的情况下,可将鱼体躯干近似视为弹性体的结论。四、对鲫鱼的形态学参数、肌肉活动模式、皮肤和肌肉本构关系、以及躯干动态弯曲实验的结果进行归纳总结,通过无量纲化的方式进行处理,得到了通用的实验数据,初步建立了“数字鱼”模型,得到了诸如“数字鱼”水平断面即为其俯视形态,且包络于NACA0014和NACA0020翼型之中的结论；并将其在鱼体结构模型建立和计算流体力学两方面进行了初步应用,反映了“数字鱼”研究的必要性和重要意义。更多还原

【Abstract】 Experimental researches on the biomechanics related to fish swimming are significant and meaningful for both scientific exploration and technical innovation. Recent advances in the diversity, precision and systematization of experimental methods and techniques lead to a general trend in quantitative researches and integrated studies on fish locomotion. Based on the control framework of "Neural Control-Active Contraction of Muscle-Passive Deformation", the morphology, electromyography (EMG), as well as the mechanical properties and constitutive relationship of the skin, muscle, and the body trunk of crucian carp are investigated with experiments, from which a simplified model of "digital fish" is established. The following work has been done in this dissertation.1. The distribution of geometric parameters and weight parameters for a single sample and multiple samples of crucian carp are studied with experiments. The linear relationship between variables, such as head length, total length, body height, et al, and standard length is acquired by the two dimensional records of different crucian carps. By use of shadow Moire method and the three-dimensional coordinate machine, the geometric parameters which characterize the 3D morphology of crucian carp are measured by comparing the experimental results. The distribution of weight parameters of crucian carp is obtained by applying slicing methods. The corresponding power function relationship between standard length and weight is clarified by statistics on different crucian carp samples.2. The electromyography(EMG) experimental technology is introduced to study the muscle activity of crucian carp during swimming, and the related operation procedures are elucidated in details. The EMG signals from red-muscle of crucian carp, which is evolving in the C-start movement, are acquired with a self-designing amplifier, after calibrated and tested by a male ECG experiment. A conclusion is drawn that there is nearly a simultaneous red muscle activity on the ipsilateral side of fish body with nearly a same duration, and the maximal amplitude of EMG locates in the anterior part of the body. Based on the electromyographic results from other fish species during steady swimming, the corresponding conclusions for crucian carp during steady swimming are inferred. Modes of the neural-control during a quick start movement, that Mauthner cell triggers motor neurons synchronously and then motivates muscle synchronous contraction, are evaluated by analyzing the activity patterns of EMG signals. Possible benefits of more muscle tension may be gained considering the special structural characteristic of the intersection between crucian carp’s muscle contracting direction and cephalocaudal axis.3. Young’s modulus, the reduced relaxation function and the reduced creep function of crucian carp’s skin and muscle are determined by failure tests, relaxation tests and creep tests with uniaxial tensile ways, respectively. Viscoelastic models are adopted to deduce the constitutive relationship, and body effective stiffness may be increased with a little energy dissipation according to the viscoelastic nature. The mechanical properties and angular stiffness of different sites on cucian carp’s body are obtained from dynamic bending experiments, where a self-designing dynamic bending test machine is employed, and a conclusion is drawn that maximal angular stiffness locates in the anterior part of the body. The conclusion of regarding the body trunk of cucian carp under dynamic bending deformation as an approximate elastomer is also confirmed.4. Based on the above experimental results of the geometric parameters, the activity patterns of muscle, the constitutive relationship of skin and muscle, and the results from dynamic bending tests, generic experimental data are obtained by normalization, and a preliminary "digital fish" model is established. Conclusions are drawn such that the horizontal transection is the overlook configuration of fish, and it is enveloped between NACA0014 and NACA0020 airfoil, and so on. Its applications are attempted on both the fish-body construction model establishment and the 2-D fish shape model related to its fluid dynamic characteristics, which reflects the necessity and significance of "digital fish" studying.更多还原