Applied Mechanics and Materials Vols. 34-35

Abstract: China is relatively successful in the development of LTMI. Both theory circle and business circle should pay extensive attentions to the development and innovation issues of LTMI. In 2002, China’s amount of exports made up 6.1% of the global value, while its proportion of low-tech (incl. middle-tech) manufactured products in global exports was up to 22.3%. In this paper, the efficiency of technological innovation in Chinese LTMI and its concrete industries are evaluated and ranked, and the reasons of gap in efficiency among industries are analyzed. This research view is more specific for the further development of different technology industries in China’s manufacturing industry and the determination of relevant policies.

Abstract: It is important that monitoring the fatigue crack propagation in engineering. This paper studied crack growth rate with the metal magnetic memory technique. Three-point bending fatigue tests of center-cracked specimens were carried out and the normal component of magnetic field signals Hp(y) on the surface of specimens were measure by TSC-1M-4. The correlation of crack growth rate da/dN and metal magnetic memory normal signal Hp(y) was studied. The specimens, with different heat treatment, quenching and thermal refining, were tested in fatigue-testing Machine to study the influence of heat treatment on the metal magnetic memory signal Hp(y). The curve of da/dN ~ Hp(y) was built.

Abstract: Measuring a large amount of parameters of work piece, resistance strain gage will have to use many resistive signal conversion boxes and long electric wires. Data acquisition becomes slow, inaccurate and discontinuous. Disorder and thermal of contact potential in the contacts affect the measurement signal and converting precision. In this paper, a wireless portable resistance strain gage is developed. ATmega16 is an 8-bit embedded and high-speed AVR single-chip microcomputer with 16k FlASH, and that is the core of system. Amplifier is designed to amplify and filter micro-voltage signals to improve measure accuracy. Wireless Bluetooth technology links ATmega16 and PC. Visual Basic software displays and processes data from ATmega16 in real time. This system is small in size and highly reliable, strong anti-interference ability and better economic performance.

Abstract: Collaborative product design is a multiple criteria group decision making process bringing different and often controversial points of view together to create a solution among stakeholders. Collaborative design possesses more perspectives than any single person possesses because stakeholders have different perspectives. This work is based on new decision approach that includes creating shared understanding among various stakeholders, contextualizing design criteria and perspectives, and creating a multiple perspective and multiple criteria decision approach, our initial effort has focused on incorporating perspectives into design process. We then provide the approach to find the optimal design decisions for consideration of stakeholders’ perspectives. By analyzing the relationships between stakeholders’ perspectives and preferences of design criteria, multi-criteria decision making approach considering the stakeholders’ perspectives can be used to monitor and control the collaborative design process.

Abstract: After analyzing and studying the existing sowing operation in forestry, a set of technological process of precision seeding based on optimal-control theory has been put forward and the prototype has also been designed and produced. This paper presents the general structure of the apparatus and analyses the working principle. An adjustable cell wheel feeding apparatus is designed to solve the problem of the uniformity of seeding. The theories of cooling mulching without adhesive on nutrition membrane and the process of membrane mulching are analyzed to set up the pressure model of the roll. After the experiments on the pressure of the roll and the analysis of the data, by the calculation of axial pressure transfer coefficient of the roll, has determined the best pressure of membrane mulching. At last, the test conditions of the prototype show that the frequency of failures is decreased, the damage rate of seeds is reduced, the seeding precision is improved, which satisfy the requirements of technical regulation on seeding in forestry and is beneficial to improve utilization ratio of good seeds.

Abstract: To solve the existing shortage of cutting drill, a multi-function excavator drill with hydraulic rotary cutting and pneumatic impact was invented on the base of market investigation, which is suitable for different rocks because of combining hydraulic rotary cutting with pneumatic impacting. If working on the soft rock, the new drill will turn off the pneumatic rock drill, replace the drill bit and only operate with the rotary power head, while on the hard rock it will operate efficiently with the rotary power head and the pneumatic rock drill. The new drill has many features, such as compact structure, the capacity of meeting a variety of drilling requirements, wider operating range, lower energy consumption, higher drilling efficiency, comfortable and flexible operation, and lower cost.

Abstract: The microstructures of B-bearing cast steel containing 0.8-1.2 wt.%B, 0.8-1.2 wt.%Cr, 1.0-1.5 wt.%Mn, 0.6-1.0 wt.%Si and 0.10-0.25 wt.%C have been characterized by means of optical OM, SEM, EPMA and XRD. The solidification structure of B-steel consists of pearlite, ferrite, martensite and boride (Fe2B), while the hardness is 1430-1480 HV. Borides distribute along the grain boundary in the form of eutectic. Fine lath martensite and eutectic Fe2B can be obtained by water quenching at 1223 K-1273 K. The hardness and impact toughness of the B-steel exceed 55 HRC and 150 kJ/m2, respectively. The abrasion resistance determined using a pin abrasion tester is obviously higher than that of the martensitic cast steel and nears to the high chromium white cast iron.

Abstract: A casting granulated metal equipment by a short flow was developed, which is comprised of pre-heating chamber, heating furnace, ceramic pipe used to transport the molten metal, the holding furnace, the drip nozzle and the cooling tank etc. The equipment can accomplish preheating the ingot, melting, holding temperature and the polluting at the same time. The preheating temperature of ingot is 100-120 °C. After the ingot is melted, the molten metal is transported to the holding furnace from the melting furnace by ceramic pipe, and the temperature in the holding furnace is 25-28 °C above the melting point of meta1. And the dwell time of granulated metal is 10-18 seconds in the cooling water box. Finally the granulated metal is directly delivered to the packing box by the bucket elevator. The granulated metal produced by a short flow has lower energy consumption and higher efficiency, and the energy consumption is 15-20% lower than that of the common flow.

Abstract: a cold extrusion forming process in die structure of plug extremity is analyzed in this paper, its technological data on the tooling structure design of plug extremity are discussed, and the die architecture design and key technology in the automatic extrusion machine for plug extremity with cold extrusion forming approach were accomplished. This plug extremity equipment developed with cold extrusion forming process technology can not only achieved the process of delivering material, extruding forming and cutting-off material in automatically, but also enhanced the rigidity and intension at two ends of plug. The production efficiency and the material used ratio were increased greatly, the manufacturing cost was decreased obviously, and the plug quality with cold extrusion forming method was ensured.

Abstract: The three dimensional finite element models of rod have been built on the basis of thermo-mechanical coupled elastic-plastic FEM in order that the rolling process of No.5 pass is simulated accurately. The distributed rule of friction is calculated and discussed with variable initial rolling temperature, diameters of rollers, reduction in pass and rolling speeds. The results show that the fore sliding region, adhesive region and back sliding region are existent on the surface of rolling material. Furthermore, friction force is calculated by using numerical simulation method and it is a new approach in studying friction. The analysis of friction force is available for reference to optimize processing parameters in the rolling process.