Jian Qiao Li

Finite Element Analysis in the Characteristics of Ostrich Foot Toenail Traveling on Sand

The ostrich foot toenail plays a crucial role in the process of ostrich foot traveling on sand. 3D laser scanner was used to measure the three-dimensional point clouds of ostrich foot toenail surface morphology, and the three-dimensional model of ostrich foot toenail was reconstructed by using reverse engineering technology. The finite element analysis in the interactions between ostrich foot toenail and sand was implemented by Abaqus and Hypermesh. The quasi-static analytical results of ostrich foot toenail inserting the sands showed that the groove structure of the toenail had a better sand fixation effects, the tiptoe structure was conducive to insert into the sands, and the inverted triangular structure of the toenail had the weak disturbance on the sands which produced the less resistance of the toenail inserting the sands. According to the velocity and the stress fields in the process of the ostrich foot toenail dynamically traveling on sand, ostrich foot toenail tiptoe could help to improve the thrust of traveling on sand, the groove area of the toenail played the effects of sand fixation and flow limitation in the process of ostrich foot toenail traveling on sand. Keywords: ostrich foot toenail, reverse engineering, model reconstruction, finite element simulation, sand fixation and flow limitation.

Effects of Load Type on the Mechanical Properties of the JLU Series Lunar Soil Simulant

The pressure-sinkage characteristics and the shear-strength characteristics of lunar regolith are the important influence factors to the trafficability of lunar rover. The performance curves and parameters of JLU luanr soil simulant were obtained by pressure-sinkage tests and shear-strength tests in the ground gravity-environmental load (1g) and the lunar gravity-environmental load (1/6g). The results show that, for the pressure-sinkage characteristics, the compression-strength of the JLU-1 is strongest, followed by the JLU-3, and the JLU-2 is the weakest. In different load levels, the deformability index n increases as the bulk density increases. The kc increase as the state becoming more and more compact,The k of JLU-1 is the largest of all, followed by JLU-3 next, JLU-2 has the smallest.The load levels have no significant effect to the tendency of n, kc and k. For the shear-strength characteristics, the shear resistance of JLU-2 is the weakest. JLU-1 has the greatest cohesion c of the three lunar soil simulant, followed by JLU-3, the c of JLU-2 is the smallest.The c of the same lunar soil simulant in natural state is greater than it in soft state. Compared with JLU-1 and JLU-3, JLU-2 has the smallest internal friction angle .The influence of the load levels to the the cohesion c internal friction angel is not obvious. The  mesured in the lunar load is wider than it in the ground load. This study will supply fundamental reference and foundation on the research and optimization of the lunar rover traveling mechanism in the authentic lunar environment.

Multiscale Simulation in Mesoscopic Dynamic Behavior of Lunar Soil Simulant Subjected to Rigid Lugged Wheel

The continuum/discontinuum multiscale analytical system of the interaction between rigid wheel and lunar soil by coupling discrete elements and matrix module was established. The DEM parameter of lunar soil particles was confirmed by the biax-test. The mesoscopic dynamic behaviors of lunar soil simulant subjected to rigid lugged wheel with different structures were simulanted and analysized by the multiscale method. Comparing the simulation results with the soil-bin test results, the multiscale model not only satisfied the computation accuracy, but also had the much higher computation efficiency.

The Liquid and Plastic Limit Data Treated System Based on VC

According to two standards for soil test methods with liquid and plastic limit combined test, a liquid and plastic limit data treated system was developed using object-oriented visual programming Microsoft Visual C++6.0 based on analytical method. The flow char indicated that programs of the system used select structure and its nested structure as main its algorithm. Contrasted with manual graphic method, the liquid and plastic limit data treated system had high efficiency and reliable accuracy.

Mechanics of Locomotion Energetics in Chinese Mitten Crab Eriocheir sinensis Milne-Edwards

The study on the locomotion mechanism in laboratory has defined performance limits for animals presently. But it is more significant for investigating mechanics of animals in their free state. In order to study the locomotion properties of Chinese mitten crabs Eriocheir sinensis Milne-Edwards on one flat terrain and four kinds of rough terrains, a high speed 3-D video recording system was used to record motion video images of crabs. The gait pattern, average speeds, the mechanical energy of the mass center and percentage energy recovery were investigated with motion analysis system. The results showed that Chinese mitten crabs used alternating tetrapod gait on flat terrain and with increasing of terrain roughness, the regularity of gait tend to be less conspicuous. Crabs used two fundamental models of energy exchanging patterns: the inverted pendulum gait and the bouncing gait and the bouncing gait was the main energy saving and conserving pattern. Keywords-biomechanics, Chinese mitten crab, rough terrain, gait, mechanical energy, percentage energy recovery

Experimental Study of Hygroscopicity of Lunar Soil Simulant

The lunar soil simulants using for vehicle-terramechanics research on the ground need to expose in air containing water molecules for a very long time. The influence of the engineering properties of lunar soil simulant caused by air moisture should be determined. This paper has obtained the moisture absorption of JLU-1, JLU-2 and SNJ-4 using weighing method. The result indicates that the hydroscopicity of three lunar soil simulant are: SNJ-4>JLU-2>JLU-1, all less than 2%. It shows that even in saturation state, the moisture content of three specimens is very little. The length of storage time of lunar soil simulant in natural environment has little effect on its engineering properties. Lunar soil simulant after be made can be storaged well for a long time in the natural environment, and used for ground foundation test. The results can supply the reference to evaluate the engineering properties and formulate the suitability standards of lunar soil simulant.

Development of Experimental-Bed for Observation of Locomotory Small Animals

The animal experimental is a fundamental equipment for biomechanics experimental, which attached to electric shock instrument, oxygen analyser or high speed recording system. The animal experimental has an advantage that it offers a single environment excluded the interfere from natural regimes. In this paper, a small animal observation experimental-bed was developed based on C++. The interface of control program was developed using Visual Basic 6.0 and the COM port communication between SCM LM3S8962 and PC was developed based on C++ Builder 6.0. The velocities of belt of the small animal experimental can run according to line, sinusoidal curves, triangular wave curves and square wave curves. Moreover, the control program provides a combined velocity based on above curves for satisfy the sophisticated experiment of locomotory small animals.

The Role of Bionic Modifications in Reducing Adhesion and Draft of Agricultural and Earthmoving Machinery

Soil adheres to the surfaces of soil engaging components of earthmoving machinery and equipment. It has been pbserved that up to 50% of energy may be consumed in overcoming adhesion and friction of soil to the surfaces of soil engaging components of agricultural and earthmoving machinery. Surface morphology, chemical composition, elasticity, lubrication mechanism and electric osmosis play significant roles in reducing adhesion, friction and energy consumption of various equipment. Some of these techniques have very limited application in the practical field conditions because of the time and amount of fluid required to achieve the desired results. Whereas other techniques are effective in reducing adhesion and friction and improving work quality of these machines and equipment. This paper analyses the forces including the drafts of conventional and bionic bulldozing blades operating under identical conditions using mathematical modelling. The force analysis showed that both adhesion and friction play major role in reducing drafts of earrthmoving machinery. It is also worth stating that both the surface morphology and the construction materials play important role in reducing adhesion and friction of ground eganging components of earthmoving machinery.

Analysis on the Movement Effect of Lunar Rover Wheel

It is important to analyze mechanical relationship between lunar wheel and lunar soil for studying passing ability of regolith in lunar soil. Mechanical relationship between lunar wheel and regolith could be reflected by these parameters such as sinkage, drawbar pull, driving torque, motion resistance and slip when the lunar wheel moves. Thus, it is necessary to analyze these parameters of lunar wheel by soil bin test. The test results show that, the four parameters increase with slip and loading, except motion resistance of the test wheel which is under 70N at the speed of 25mm/s. The variations of the four parameters are not significantly influenced by velocity. The variations of the four parameters are significantly influenced by loading.

An Inchworm Bionic Stepping Actuator Based on PZT/ER Hybrid Dive and Control

An unconventional inchworm stepping actuator based on bionics is presented, which consists of driving unit (PZT stack pump), fluid control unit (ER fluids valve), actuating mechanism (precision hydraulic cylinder). As a new type of precision force/ displacement driving and positioning system, it inherits the advantages of conventional inchworm actuators, and also has its own remarkable characteristics, such as that stepping displacement can be adjusted precisely through varying the working voltage and frequency, etc. The driving unit is actuated jointly by double PZT stacks; Multi-channel parallel cylindrical ER fluids valve is designed as the control valve. In the lab, the inchworm bionic stepping actuator based on PZT/ ER hybrid dive and control is designed and manufactured, and the related performances are testedsystematically. The maximum driving force reaches 49N, and the step size and driving speed VS the working voltage shows a good linear relationship under three different signal waveforms. At the same time, in the frequency range less than 40Hz, the driving speed VS the frequency approximately shows a linear relationship. When working voltage is 100V and rectangle wave signal inputs, the step size reaches 12.6μm. When the working voltage and frequency is 100V, 40Hz, respectively, the driving speed reaches 420μm/s. The maximum drive speed of test prototype reaches 1051 μm/s, when working in frequency 75 Hz. The systematic test shows that the method using PZT and ER hybrid drive and control technology to develop a new type of inchworm bionic stepping actuator is feasible, which provides a reference for the future development of new type of actuator.