Applied Mechanics and Materials Vols. 52-54

Abstract: Non-obstructive particle damping (NOPD) is a new composite damping technology based on traditional partical damping and impacting damping, and it has good vibration-reduced results. Through studying thermodynamics constraint condition for non-inverse variation of inner tissue structure of the material, the endochronic theory obtained variation regularity of inner variable, further gave out evolution path of specific non-inverse thermodynamics variable under specific condition, and thus the constitutive relationship of the material was obtained. Based on endochronic theory, an incremental form of the endochronic constitutive relationship of discrete particle was derived, and then penalty element was introduced to solve the connection problem between structure and discrete particle, lastly finite element dynamics equation of NOPD composite structure was constructed. Based on the model of NOPD composite structure, simulation and experiment for response of NOPD free beam were made. It indicated that applying endochronic theory to analyze the response of NOPD is rational, which supplied an effective method for engineering application of NOPD.

Abstract: The GO2/ethanol/water tripropellant evaporation and combustion in axisymmetric combustion chamber was numerically simulated. The different characteristics of the evaporation and combustion between dilative and traditional un-dilative entrance, and the different dilation-angles of the combustion chamber entrance are analyzed. The results indicate that the dilative entrance combustion chamber is benefit for thermal protection of the injection, and the flamelet backpedals with increase of the entrance dilation-angle. At the same time, that dilative inlet combustion chamber reduces the evaporation of the liquid component seriously. The evaporation rate decreases with the increase of the dilation-angle at first, but after the dilation-angle is bigger than a critical one, it increases.

Abstract: Integrating traditional engine and plunger pump, a new type power equipment─Internal Combustion Fluid Pump(ICFP) was developed, through which thermal energy can be turned into hydraulic pressure directly. As a main factor affecting ICFP’s performances, efficiency is the basis to design its structure. For three-cylinder axial ICFP, it’s dynamics model was setup, and its efficiency character was studied. The simulating results show that ICFP’s effective thermal efficiency is 37.44% at calibration condition, which is higher than engine-pump system by 23.06%. For the three-cylinder ICFP, the effective thermal efficiency experiments are done. Errors are within 5%, and it proved that the simulation results are correct.

Abstract: Laser confocal probe, on an active focus adjusting principle, was introduced in this paper. This kind of non-contact laser probe has the abilities to do the detection on strong reflection of the surface of high precision metal parts and optical devices. So, a problem of shape inspection detection was resolved. The micro-sphere is the key element in the ICF (short for inertial confinement fusion) system. The success or failure of "Ignition" is directly related to the accuracy of the assembly location of micro-sphere in the micro-target. Because of the particularity of the micro-sphere, laser confocal probe is used to do the detection of the center error of micro-sphere. The required measurement precision is less than 3µm. The mathematical formula between the height defference or the displacement value of measured surface and the displacement valued of the tuning fork can be gotten by the time different principle. Good stability of frequency and the swing of tuning fork, which approved through the experiments, have little influence to the time different Δt and the final measurement results.

Abstract: The aims that indicated in "The Guidance Outline on Elementary and Middle Schools Information Technology Curriculum” are to enable students to have abilities of acquiring, transmitting, processing and applying information through learning information technology courses; cultivate them to have good information literacy; make information technology as a significant way of supporting for lifelong and cooperative learning, laying a necessary foundation of adapting to the study, work and life in information society. With the application of multimedia computers and networks, education and teaching have undergone profound changes that the integration of information technology and subject teaching (or course) has become the focus in educational reform, so how to integrate instruction with the information technology curriculum I think the idea that combing with other subjects teaching in the information technology curriculum to carry out thematic inquiry learning not only can achieve unique effects, but also is a win-win teaching model of information technology and other teaching courses. This paper aims at exploring the positive ways and meaning of the integration of information technology and other subjects through thematic inquiry learning cases.

Abstract: In seismic prospecting, the over sample combined with low quantity is used to converter input analog signals to 1-bit data flow. In order to realize decimation filtering for the high speed low resolution signal produced in the process of seismic prospecting, the CIC decimation filter is introduced into seismic survey system to achieve decimation and filting. The principle and the shortcoming were analyzed; finally an ISOP filter is introduced to compensate the pass-band attenuation, Simulation showed it could improve the performance of CIC filter, the cascade of CIC and ISOP is suitable for seismic prospecting system.

Abstract: This paper presents a simple and systematic modular approach for kinematic analysis of complicated Parallel Kinematic Manipulators (in short, PKMs) which coupled degrees are more than 2. (1) Single open chains (in short, SOCs) may be regarded as the basic modules of a PKM. Any PKM can always be decomposed automatically into a set of ordered SOCs, and these SOCs can also be used to recognize the basic kinematic chains contained in it. (2) The kinematic analysis algorithms and the compatibility conditions of the SOC modules are offered. (3) Directly applying the above SOC kinematic modules, the kinematic equations of a PKM can be automatically established. (4) In order to solve kinematic equations of complicated parallel manipulators which coupled degrees are more than 2, a new searching algorithm which requires no initial guess has been presented. The procedural approach is demonstrated in parallel manipulators.

Abstract: TiAl/Ti2AlC in situ composite was successfully fabricated by hot-press-assisted reaction process from the mixture of Ti, Al and carbon black. The phase formation and transformation were investigated in detail by X-ray diffraction (XRD) and the morphology characteristics were also studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that when the mixed powders were hot pressed at 1300 °C for 1 h, full dense and highly pure TiAl/Ti2AlC composite was synthesized. The TiAl was the matrix phase and the in situ synthesized Ti2AlC was reinforcing phase. The reaction process was also discussed.

Abstract: Elemental mixture of Ti, Al and C was high energy milled in a planetary ball mill under high-purity nitrogen gas protection and then hot pressed. The fully dense bulk layered ternary Ti2AlN0.5C0.5 with sub-micron grain size was successfully obtained. The phase formation and transformation in high energy milling and subsequently hot press sintering were studied in detail by using X-ray diffraction (XRD). Scanning electron microscopy (SEM) linked with energy dispersive spectroscopy (EDS) was used for the structural and compositional analysis. The formation mechanism was also discussed.

Abstract: Researches of wave motion are important on theory and application. The forward problem and the backward problem are the two aspects that relate with each other. In this paper, with the combination of FEM considering BGT absorbing boundary condition for forward problem and GA method, the inversion of target’s characters in infinite area is discussed. The absorbing boundary condition is obtained through approximating the Sommerfeld radiation condition. Although the absorbing boundary condition can’t simulate the effect exactly, it can reach the limitation in the practice and has the character of solving the coupling that simplifies the calculations. Because of the use of finite element model method, the forward problems that involve special geometrical shaped scatter and multi scatters can be solved. The finite element model is used iteratively to compute the scattered field. In the inversion process, the GA method is adopted because of its advantage of global optimum search and parallel calculation. The numerical simulation examples of single and multiple show the validity of this method.