Papers by Author: Yan Ma

Abstract: This paper put forward the method to calculate screw holding capability for micron wood fiber molded products. First, the mechanical model of screw holding capability has been established. Second, the function of force distributing to the threads has been deduced. Finally, the equation of screw holding capability was put forward. Using this method, we can calculate the screw holding capability of micron wood fiber molded products for screws of various geometric parameters by means of computer rapidly. The strength safety can be estimate for screw joints in micron wood fiber molded products accurately.

Abstract: When the intermediate cuttings cut the wood, the efficiency of the vibration of the circular saw web was low so that the saw web always broke off. Moreover, the high-speed rotation would cause the vibration of the complete machine and result in the initial failure of the machine. Therefore, seeing from the problems from the analysis above and practice, the new design of the current micro intermediate cuttings seemed especially important. In the thesis, the author made a new arrangement of the micro intermediate cuttings of machinery tools, carrying out three-dimensional modeling and simulation of the complete machine and made an analysis of the dynamic cutting process by means of analyzing the working condition of circular saw web.

Abstract: The test bed for micron paring machining is a kind of Computer numerical control (CNC) carpentry test beds. Movement of machine is controlled automatically according to processing instructions, machining of different raw materials can be realized by simply changing the processing instruction program. The test bed’s precision and its persistence are mainly guaranteed by the lathe bed, and have an air clamping device and its feeding mechanism includes a stepper motor for CNC feeding. At the end of the thesis, the conclusion of experiment presents widths of micron parings machined by cutting lengthways along the grain fall between 50~150 µm. With further analysis, around 72% of the parings are 60~100 µm thick, around 75% are 5~8 mm wide, around 78% are 65~75 mm long. The results show micron parings machined by the specialised test bed meet the design requirements for micron parings.

Abstract: Using the powerful parametric features of Pro/E modeling for the assembly of the track board, and building up Three-dimensional solid modeling. Finite element analysis with the simulation of mechanical motion to simulate the track through the soft ground of the forest were carried out. It can significantly reduce the design costs and speed up the development cycle to adapt of the requirements of the modern forestry industry.

Abstract: This paper aims at the factors that the design needed to be considered. There are diameter and structural of defibrator millstone and the rotational speed and torque of millstone and so on. To optimize the cutting disc size and subarea size and the number of cutting disc fan block etc. which will influence the indicator of performance parameters of cutting disc and to arrive at a more reasonable design parameters via the Monte Carlo simulation method.

Abstract: The working principle of the micro-CHP based on biomass direct-fired Stirling engine and the thermal energy conversion process of the biomass direct-fired fuels were analyzed. On the basis of analysis, a 1kW β-type Stirling generator was designed and constructed for lab tests. Then, experiments were carried out to evaluate the effectiveness of the prototype. Through the analysis of experimental data and simulation, the change law of charge voltage, charge current with the engine speed and pressure, as well as the relation of heat and electricity, the power generation efficiency and the overall efficiency of the thermoelectric in the working process was obtained. The results showed that biomass energy use efficiency will be improved through the use of micro-CHP based on biomass direct-fired Stirling engine.

Abstract: Based on the study of the mechanics features of pneumatic artificial muscle including the nonlinearities in material, geometry, and with the method of nonlinear finite element analysis, the three-dimensional finite element model of a pneumatic artificial muscle was established. The analytical results were confirmed by the experiment with the use of a pneumatic artificial muscle test bench.

Abstract: The basic assumption which using the wooden cases technology in the electronically controlled forestry walking robot was proposed, and the lightweight new material improved the rate of the walking robot. The mechanical model of shell of the walking robot was built, and the mechanical analysis was carried out on it. The equation of the shell which encountered with the external collision was listed and the internal forces and deformation of the shell vertex were obtained under the external collision. The intensity of the shell of mobile walking mechanical which is consist of the wood fiber composite was verified, which put forward innovative solutions for the design of the electronically controlled forestry walking robot.

Abstract: In the process of preparing superfine wood-flour with physical method, when the size of wood-flour particle reaches to the corresponding level, a single wood cell will be destroyed. In the process of analyzing micro-nano wood-flour’s cutting power, the process of cell disruption of the wood cell needs to be computed. Based on the relevant theory of finite element and structural mechanics, this article builds a structure mode of 12 lever hexagon truss model to simulate the cellular structure. There are 6 levers outside to simulate the cell and 6 levers inside to simulate the internal pressure. This establishes a single cell stress model to analyze its stress. It can be obtained that when the size of the force acting on the node reaches the unit force, the minimum tensile stress of the bar element is bigger than the macroscopic tensile strength of the wood. According to the structural characteristics of the cell wall, this paper compares the tensile stress along the grain of the bar element with the tradition cutting stress. Using tensile strength as the criteria to test the rupture failure of Cryptomeria fortunei cell, the wood cell’s disruption force can be concluded. When preparing superfine wood-flour with Cryptomeria fortunei as experimental raw materials, the calculated results of applying the traditional cutting theory to calculate the cutting force has proved the analysis structure of Cryptomeria cell micromechanics with the method of finite element and structural mechanics, so that it can be concluded that certain cutting force can make Cryptomeria fortunei cells disruption.

Abstract: This paper proposes a idea of microfibril preparation with physical methods. Through the design of wedge structure of experiment table and with the condition of the dynamic pressure jet putting the soften the micro wood fibers to cell wall by squeezing and shearing and torsion and so on and forming the microfibril test specimen. This paper describes the development of foreign microibrils of the status, pointing out the significance of microfibril preparation and application prospects. And to develop the corresponding technical route and to analyze the feasibility of microfibril preparation.