【作者】 刘财勇；

【导师】 佟金；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2008， 博士

【摘要】 结合金属切削原理,从切削刀具(爪趾)和切削运动(爪趾与洞壁的相对运动)两方面对鼹鼠挖掘机理进行研究。在研究过程中,从爪趾形态和材料性能两个方面进行了切削刀具(爪趾)的分析。利用体视显微镜对鼹鼠爪趾宏观几何形态进行了分析,并拟合了爪趾边缘曲线。使用游标卡尺测量了鼹鼠前爪爪趾的几何尺寸。基于逆向工程技术,使用基于点一线一面方法对鼹鼠爪趾进行了生物体表模型重构。在前爪爪爪趾表面建模的基础上,对爪趾表面特征进行了量化分析。使用体视显微镜和扫描电子显微镜对鼹鼠爪趾的断面结构进行了观察,通过显微硬度和纳米硬度试验研究了爪趾的表面硬度、断面各层硬度和弹性模量等力学性能。运用金属切削原理分析了鼹鼠爪趾的运动特性,获得爪趾的运动轨迹、切削运动、切削用量、爪趾切削结构及其几何参数,建立鼹鼠爪趾仿生切削原理,为建立仿生挖掘与切削理论奠定了基础。更多还原

【Abstract】 The mole rats are good at digging and can dig through a 300-foot long tunnel in just one night. In addition, moles have a peculiar digging mechanism, humeral rotation digging. Their manus are the main tools for digging soils. The wide and shovel-like manus has five digits and grows outwards. All these above result from the long-term evolution in the soil environment. The claw of the manus is the bionic prototype for the soil cutting tools and excavation tools. Studies on them can provide the useful biologic information for the bionic cutting technology and the design of soil cutting tools and excavation tools.Coupled with the metal cutting theory, the cutting process used by the mole rats was studied from the claw and the relative movement between claws and tunnel wall, and the studies of claws included their morphology and material performance.1. Aspect of clawThe macro-geometry of claws for the mole rats was made the qualitative and quantitative analysis using the stereomicroscopy and the reverse engineering. The claws of manus are similar in shape. Among them the three middle claws are a little round and the two outer claws are a little tip. All the claws are obviously curved in the transverse and longitudinal direction. They are thin at the tip and thick at the root. In addition, the three middle claws have a larger value in length, width and thickness than the two outer claws. The dorsal surface of claws is smoother than the ventral surface. The lower edge of front section is smoother than the upper edge for the claw 1 and 2; they are approximately symmetrical for claw 3; on the contrary for the claw 4 and 5. The lower and upper edges of hind section can be considered as the straight line through the fitting for all claws.The data clouds of ventral and dorsal surface of the claw for the mole’s manus were obtained with 3-D laser scanning system. The surface reconstruction was made using the point-line-surface method after they were reduced and made the smoothing processing. Moreover, the model precision of surface reconstruction was analyzed. The results showed that the precision was satisfactory and the surface reconstruction can be used for the quantitative analysis of geometric shape for the mole’s claw.Based on the claw’s model, the quantitative analysis of surface characteristic was made. The second derivative and curvature of contour curves were calculated, accordingly the surface characteristic of claws was concluded. The results showed that the dorsal and ventral surface have the smaller vertical bending and more lateral bending. The dorsal surface is smoother than ventral surface. The ventral surface characteristic influenced the cutting performances of the claw.The section structure of claw was examined by carrying out the stereomicroscopy and scanning electronic microscopy （SEM）. It was found that the claw mainly comprises four layers: the dorsal layer （DL）, the ventral layer （VL）, the intermediate layer （IL） and strengthening layer （SL）. The mechanical properties were studied in micro- and nano-indentation experiments, including the surface hardness, section hardness and elastic modulus. The results showed that the dorsal hardness （DH） of the claw is harder than the ventral hardness （VL）, that the tip hardness is harder than the central hardness, and that the claw is consist of a hard core covered by the softer layers.2. Aspect of relative movement between claws and tunnel wallThe test results show that the movement trajectory of mole rats’ foreleg has three vectors: vector X, in the direction of body width; vector Y, in the direction of body length; vector Z, in the direction of body hight. The cutting amount in the direction of body width is larger than that in the direction of body hight.By means of the metal cutting theory, the cutting theory of mole rat’s claw was preliminary established. During the soil cutting process, the cutting movement of claws is composed of one main movement V_c, the rotation of humerus around the axis of humerus, and two feeding movements V_f1 and V_f2, the forward movement of body and the rotation of elbow respectively. The cutting amount and cutting structure parameters of claws were defined. Moreover, the applications of the cutting theory of mole rat’s claw were discussed.By the help of the cutting theory of metal, the cutting mechanism of claws of the mole-rat was studied from the shape, material performance and cutting behavior of the claw, which has the significance for building the bionic excavating and cutting theory.更多还原