Papers by Author: Shan Shan Hu

Abstract: Sawing concrete with diamond saw blade is a complex process with alternating loading. However, due to the poor working conditions of the thin circular blade made of high manganese steel core, and the lack of research on its failure mechanism, a large number of used blade are abandoned every year in China and all over the world without steel core reused. Therefore, exploring the failure mechanism of diamond saw blade can improve the cutting quality and efficiency, and extend the service life of the saw blade. In this paper, the failure mechanism of diamond saw blade sawing concrete was analyzed through segment wear experiment and microstructure observation of segments and steel core of failed sawblade. The results showed that the stress concentration exited at the bottom of slot, where it became the most dangerous section. The crack at the bottom of the cooling hole caused the saw blade to deviate violently and bear unevenly. The microstructure is great different along the outer to the center of the steel core. The closer to the teeth of the saw blade, the more obvious the microstructure change, while the central core still retains the original structure. Under the same sawing area of 0.01m², the stable dust adhesion of plain concrete is less than that of the steel fiber concrete. However, when the dust adhesion increases to more than the stable adhesion, the phenomenon of blockage will occur. Therefore, deflection, crack, wear and burn were the main failure reasons of diamond saw blade when sawing concrete.

Abstract: 2205 duplex (austenitic-ferritic) stainless steel has a good weldability and an excellent corrosion resistance. The good weldability is achieved when in close to 50-50 ferrite-austenite ratio. In this study, the welding process and properties were investigated by pulsed Nd:YAG laser welding. Tensile test, surface microhardness test, surface topography and microstructures of 2205 duplex stainless steel welds were performed under different welding speeds, input currents, pulse widths, frequencies and defocus distance. The relationship among them was revealed and the optimal welding parameters were obtained. The results showed in the condition of I = 160 A, T = 5 ms, f = 25 Hz, V = 500 mm/min and Z =-1 mm, the amount of ferrite and austenite in welds was roughly same, overlap rate of solder joints was above 78% and the weldability was good.

Abstract: Experiments of diamond sawblade sawing plain concrete are conducted with different sawing parameters. Real time signals of sawing force, vibration, acoustic emission and noise are collected, and Multi-scale wavelet analysis is adopted to analyze the interrelationship and interrelation of real time signals. Supervision and distinction of processing can achieved after Multi-scale wavelet analysis.

Abstract: t is known that cutting force is the key to reasonably select cutting parameters, and the base to study the cutting mechanism. Genetic Algorithm and multiple regression analysis were adopted to achieve cutting force predicted model of multi-diamonds fast milling hard-brittle materials with defined diamond grains pattern by single diamond fast milling hard-brittle materials experiments. Results show that cutting force predicted model by genetic algorithm has higher precision than that model by multiple regression, and the cutting force prediction method based on genetic algorithm is more suitable for those hard-brittle materials which components are relatively soft and simple. Predicted model can afford another study direction for processing analysis of diamond tools, tools making and processing parameters selection from the view of diamond grain practice cutting.

Abstract: Annual cold heat adjustment is one of the key problems in the practical application of ground-source heat pump system. According to the energy-consuming characteristics of the building in hot summer and warm winter area zone and engineering practice, the author puts forward the multi-level heat shunt ground source heat pump systems(GSHPS). Reasonable system can be matched according to the characteristics of the cold water chiller and the water source heat pump, which takes full advantages of soil cold/heat source, improves the efficiency of the soil heat exchanger, and balances underground temperature field effectively.

Abstract: Taking one club as example, the application of the subtropical region ground source heat pump technology on indoor constant temperature swimming pool water heating load calculation and type selection of equipment is introduced. The system performance is analyzed through the experiment. The energy consumption cost of this technique is compared with electric boiler and oil-fired boiler, and the result shows ground source heat pump technique is superior and economic.

Abstract: Material fracture character of marble processing by single diamond tools was studied by single diamond indentation experiment and fast milling experiment. The surface morphology and inner cracks were achieved based on double lights transmission of stereomicroscope, marble semitransparent character and SEM technology. Results showed Indentation cracks break crystal or extend along cleavage plane from three directions. The marble indentation fracture progress could be divided into three phases: plastic deformation, fracture deformation and block broken. Material broken types were diverse for different compositions in marble.

Abstract: X-axis and Y-axis workbenches are important parts of PCB drilling machine. Theirs dynamic properties directly affect the overall performance of drilling machine. Modal analysis method was adopted in this paper. Measurement and analysis on vibration of X-axis and Y-axis workbenches based on LMS Test. Lab was carried out. The modal parameters such as natural frequency, damping ratio and corresponding vibration modes were obtained. The results present that the X-axis and Y-axis workbenches have a high fundamental frequency, which is 564Hz and 1014Hz respectively. And the damping ratio is less than 4.91% and 2.99%, which shows that the stiffness of the X-axis and Y-axis workbenches are higher. The FEM modal analysis shows that it has the similar results with the experiments in modal parameters. The analysis of natural characteristics of workbench provides guidance for optimizing machining parameters of drilling and improving structure of workbench.

Abstract: For defects of low-plastic, brittle damage and micro-crack, brittle-hard materials are often collapsed and ruptured, and processing surface was made by complicated micro grooves after repeated processing. In order to know the complex rules of surface generation, series tests of diamond abrasives scratching glass with different processing paths and depth of cut were done. Cutting force and acoustic emission signal were collected. Crack generation, path interference, dynamic characteristic of glass processing were observed.

Abstract: By FEM module analysis and temperature distribution analysis of diamond saw blade with multi-holes base and different segment width, influence of different hole diameter, hole number and segment width to nature frequency is clear. Adopted single-factor test, sawing force and acoustic emission signal are measured by cutting several kinds of strength concrete in different cutting parameters. The analysis to characters of sawing force and acoustic emission helps to find out optimum structure of diamond saw blade with different segment width, more rational sawing parameter and its adaptability to workpiece material.