【作者】 张赫；

【导师】 韩志武；

【作者基本信息】 吉林大学 ， 仿生科学与工程， 2024， 硕士

【摘要】 航天器在轨运行期间,由星上活动部件产生的微振动严重干扰了载荷系统的任务完成精度,直接影响了航天任务的最终实现品质。随着高分辨率地球观测遥感卫星的发展,航天领域对微振动抑制技术的需求日益增加,光学遥感卫星微振动抑制技术具有巨大的发展空间。然而,星上活动部件众多,产生的微振动具有频带宽、幅值小的特点,传统振动抑制方法在1-500 Hz中低频段的振动抑制效果较差,难以满足星上扰振抑制需求。与此同时,面向星上载荷系统应用场景,微振动抑制构件还需具备一定的刚度,现有阻尼材料往往难以兼顾高刚度和高阻尼性能,因此,亟需提出高阻尼高刚度的低频振动抑制构件设计新方法。相比之下,自然界的生物复合材料通过特殊的功能结构形态和材料组合方式,展现了优异的刚度和强度,实现了静态承载能力与动态阻尼性能的和谐共存。红耳龟(red-eared silder turtle)外壳承受两种载荷,一是由于坠落或捕食者的攻击而产生的高强度、高速率的冲击载荷,二是由于行走、呼吸、游泳和进食过程中产生的低强度循环载荷。生境使然,红耳龟背板承受微小载荷时呈柔性,以便在受到小幅值低强度载荷时允许小的变形,大载荷则呈刚性,以抵抗高速率载荷和大的变形。这种集优异阻尼特性和刚度特性于一体的天然复合材料为高性能微振动抑制构件设计提供了新策略。因此,本文将以红耳龟背板高阻尼高刚度的结构为研究对象,从“结构-材料-功能”角度展开系统化的研究。本文对红耳龟背板进行了宏微观跨尺度量化表征,获取了相关的振动抑制结构参数,并对其化学组分进行分析,确定其元素及组成成分;分别对新鲜和风干的红耳龟背板缝合区,进行准静态力学和动态力学性能测试,综合分析缝合线结构小变形下高阻尼,大载荷下高刚度的内在机理;受缝合线结构特征的启发,设计了系列化具有缝合结构的仿生结构化材料模型,对模型进行仿真模态分析,提取缝合维度、角度和尺度等影响因素,进行仿生微振动抑制结构化样件的参数优化;采用多喷头高精度3D打印的技术制造仿生结构化材料样件,并对样件进行动态力学性能测试,通过工艺参数改进获取最优样件,并对其阻尼效果、振动抑制性能进行分区域讨论分析。具体研究工作如下:(1)获取了红耳龟背板缝合结构的形貌参数、材料成分、功能特性等要素对红耳龟背板进行宏微观表征、成分分析以及力学测试,发现龟壳背板由多个板块相互拼接,其接缝处呈现三维立体的缝合网状结构,呈现较为规则的凸起与凹陷,缝合结构两侧坚硬的骨质以软质的粘弹性纤维状胶原蛋白相互粘合连接。对新鲜和脱水的龟壳背板样品分别进行静力学和动力学分析研究,表明缝线可以赋予龟甲更大的柔韧性、更高的韧性和更大的变形能力。与脱水样品相比,新鲜的龟壳软质的缝合线结构通过牺牲31.6%的刚度性能,使得韧性增强,更有利于微小变形下吸收振动能量,提升351.4%的阻尼性能。(2)揭示了红耳龟背板缝合结构的内在微振动抑制机制基于红耳龟背板缝合结构的关键参数,建立了二维力学简化模型与三维力学模型,分别进行理论计算与仿真分析。从阻尼特性、刚度特性两个切入点进行机理研究,预测了缝合区背板的一般力学行为,揭示了红耳龟背板缝合结构内在的微振动抑制性能与缝合线形几何参数的复杂关系,推论出龟壳缝合区背板在微小变形下具备优异的阻尼性能,当载荷达到背板的临界变形阈值时,相邻骨骼区域的硬质凹凸对立端相抵,形成互锁结构,龟壳背板由此实现刚性增强。(3)提出了仿生微振动抑制结构化材料的设计方法基于红耳龟背板缝合结构高阻尼高刚度内在机理启发,设计了仿生微振动抑制结构化材料。经过模型解构的模态分析及公式推导得出,随着缝合结构维度的增加和缝合结构角度的减小,梁的一阶固有频率增大,说明其互锁性和结构的刚度得到了明显提升;综合考虑尺度、角度和维度因素,设计了软硬两种材料结合的仿生人字形三维缝合网络胞元及其铺排的振动抑制构件。(4)实现了仿生微振动抑制板材样件的可控制造采用3D打印技术进行多组结构梁,以及仿生人字形三维缝合网络板材样件制造,并进行振动衰减测试。通过损耗因子的对比,得到了仿生结构化材料的阻尼特性。在1-500 Hz以内,样件的最大振动衰减率为74%,说明仿生人字形三维缝合网络结构板材具有良好的微振动抑制效果。随着缝合结构条数的增加,微振动抑制效果愈加明显。验证了本文所述的三维缝合网络结构板材在实际应用中的可行性,为新型微振动抑制结构化材料的设计制造提供理论参考和技术支持。更多还原

【Abstract】 During the on-orbit operation of spacecraft,micro-vibrations generated by onboard moving parts seriously affect the accuracy of the payload system,which directly affects the final quality of the space mission.With the development of high-resolution earth observation remote sensing satellites,the demand for microvibration suppression technology in the aerospace field is increasing,and microvibration suppression technology for optical remote sensing satellites has a huge development space.However,there are many moving parts on the star,and the microvibration generated has the characteristics of wide bandwidth and small amplitude,and the traditional vibration suppression method has poor vibration suppression effect in the middle and low frequency bands of 1-500 Hz,which is difficult to meet the demand for on-board disturbance vibration suppression.At the same time,for on-board load system application scenarios,micro vibration suppression components also need to have a certain degree of rigidity,the existing damping materials are often difficult to take into account the high rigidity and high damping performance,so there is an urgent need to propose a new method of high damping and high rigidity design of low-frequency vibration suppression components.In contrast,nature’s biocomposites exhibit excellent stiffness and strength through special functional structural morphology and material combination methods,achieving a harmonious coexistence of static load-bearing capacity and dynamic damping performance.red-eared silder turtle is subject to two types of loading: high intensity,high rate impact loading due to falls or predator attacks,and low intensity cyclic loading due to walking,breathing,swimming and feeding.In its natural habitat,the red-eared silder turtle shell is flexible at low loads to allow for small deformations during lowintensity,low-amplitude loading,and rigid at high loads to withstand high-rate loading and large deformations.This natural composite material,which combines excellent damping and stiffness properties,provides a new strategy for the design of high performance micro-vibration damping components.Therefore,this paper takes the high damping and high stiffness structure of red-eared slider as the research object and conducts systematic research from the perspective of "structure-material-function".In this paper,we quantitatively characterize the red-eared silder turtle backboard at macro and micro scales,obtain the relevant vibration suppression structural parameters,and analyse its chemical components to determine its elements and composition;we conduct quasi-static mechanical and dynamic mechanical property tests on the seam area of fresh and air-dried red-eared silder turtle backboards,respectively,to comprehensively analyse the intrinsic mechanism of high damping under small deformation and high stiffness under large load of the seam structure;We design a series of biomimetic structured material models with seam structure inspired by the structural characteristics of the seam;we extract the influencing factors such as seam dimension,angle and scale,and perform simulation modal analysis on the model.Inspired by the structural characteristics of the seam,a series of biomimetic structured material models with seam structure are designed,and simulation modal analysis is performed on the models to extract the influencing factors such as seam dimension,angle and scale,and to optimise the parameters of the structured samples with biomimetic microvibration suppression;the samples of biomimetic structured materials are produced by adopting the technology of high-precision multi-jet 3D printing,and the samples are subjected to the dynamic mechanical property tests,and the optimal samples are obtained by improving the process parameters,and the samples are tested by optimising the process parameters.Improvement to obtain the optimal sample,and its damping effect,vibration suppression performance of the sub-regional discussion and analysis.The specific research work is as follows:(1)To determine the morphological parameters,material composition,functional properties and other elements of the seam structure of the dorsal shell plate of the redeared silder turtle.Macroscopic characterisation,compositional analysis and mechanical testing of the red-eared silder turtle dorsal plate revealed that the dorsal plate of the turtle shell is composed of multiple plates joined together,and its sutures show a three-dimensional suture mesh structure with more regular peaks and valleys,and the hard bone on both sides of the suture structure is joined together by soft viscoelastic fibrillar collagen adhesive bonds.Static and dynamic analyses of fresh and dehydrated turtle shell dorsal plate samples showed that the sutures could provide greater flexibility,toughness and deformability to the turtle shell.Compared to the dehydrated samples,the soft suture structure of the fresh turtle shell allows for increased toughness by sacrificing 31.6%of the stiffness performance,which is more conducive to absorbing vibration energy under small deformations,and improves the damping performance by 351.4%.(2)The intrinsic microvibration suppression mechanism of the suture structure of the dorsal plate of the red-eared silder turtle is revealed.Based on the key parameters of the suture structure of the red-eared silder turtle dorsal plate,a two-dimensional simplified mechanical model and a three-dimensional mechanical model were established,and theoretical calculations and simulation analyses were carried out,respectively.The mechanism is investigated from two entry points,namely damping and stiffness,and the general mechanical behaviour of the back plate in the suture zone is predicted.The complex relationship between the intrinsic microvibration suppression performance of the backplate suture structure of the redeared slider and the geometric parameters of the suture line shape is revealed,and it is deduced that the backplate of the suture zone of the turtle shell has excellent damping performance under the small deformation,and the rigid concave and convex opposites of the adjacent skeletal region form an interlocking structure when the load reaches the threshold of the critical deformation of the backplate.When the load reaches the critical deformation threshold,the rigid concave-convex opposites of the adjacent skeletal regions are pitted against each other to form an interlocking structure,and the tortoise shell backplate achieves enhanced rigidity.(3)Proposed design method of bionic microvibration suppression structured materialsInspired by the intrinsic mechanism of high damping and high stiffness of the back plate suture structure of the red-eared slider,a biomimetic microvibration suppression structured material was designed.After the modal analysis of model deconstruction and formula derivation,it is concluded that the first-order eigenfrequency of the beam increases with the increase of the dimension of the suture structure and the decrease of the angle of the suture structure,indicating that the interlocking property and the stiffness of the structure have been significantly improved;Considering the factors of scale,angle and dimension,the biomimetic herringbone three-dimensional suture network cytosol combining the two kinds of materials,namely soft and hard,and its layup vibration suppression components are designed.(4)Controlled fabrication of bionic micro-vibration damping plate samples achievedSeveral sets of structured beams and bionic herringbone three-dimensional mesh plate samples were fabricated using 3D printing technology and vibration damping tests were conducted.The damping characteristics of the bionic structured materials were obtained by comparing loss factors.Within 1-500 Hz,the maximum vibration damping rate of the sample is 74%,indicating that the bionic herringbone three-dimensional stitching network structured plate has a good microvibration suppression effect.The microvibration suppression effect becomes more obvious as the number of suture structure strips increases.It verifies the feasibility of the three-dimensional suture network structured plate described in this paper in practical applications,and provides theoretical reference and technical support for the design and manufacture of new microvibration suppression structured materials.更多还原