Abstract: A new blue photochromic diarylethene compound, 1-[2-methyl-5-aldehydeyl-3-thienyl]-2- [1,2-dimethyl-5-cyanoyl-3-pyrroleyl]perfluorocyclopentene (1a), was synthesized and its photochemical properties, such as photochromism in solution and in PMMA amorphous film, fluorescence and optical storage properties were investigated in detail. The results showed that it can be useful in fluorescence molecule switch, scale optoelectronics and potential use for data storage.
Abstract: The objective of this study is to investigate the effect of ultrasonic reflection echo during polymer mixing process in the internal mixer. Phase change from solid to liquid, partially melted pellets, and distributing progress of CaCO3 powder during the melting process of low density polyethylene (LDPE) and the mixing process of the melted LDPE with a calcium carbonate (CaCO3) powder were successfully monitored by ultrasound. Melting and mixing completions were determined when ultrasonic reflection echo reached its upper stable level. The mixing period was proportional to the mass of added CaCO3 powder. The mean peak value of ultrasonic reflection L2f echo at the upper stable level decreased when the total amount of added CaCO3 powder increased. The presented ultrasonic technique can be utilized to optimize the melting and mixing processes, reduce cost and evaluate melting and mixing quality.
Abstract: Unidirectional pore structured porous mullite composite has been fabricated using a TBA-based freeze-gelcasting of coal fly ash/alumina slurries. After sintering at 1300-1500o C, the shrinkage, apparent porosity and compressive strength of the resulting porous composites were investigated. After sintering at 1500o C, the composite showed the maximum compressive strength of ~51 MPa and the minimum apparent porosity of ~64%.
Abstract: A new type of wear-resistant hydraulic feedback self-sealing plunger pump is proposed. finite element analysis and optimal design of orthogonal parameters are applied to determine the structural parameters. The pump overcomes the conventional piston friction, low efficiency, short life. Laboratory tests showed that the pump free down stroke, full returns, leakage reduction 1,000 times than the standard API. Field experiments indicate that pump efficiency attain to 60-80%, achieved a good energy saving effect of improving the pump efficiency.
Abstract: In this investigation, we propose a new concept to embed cohesive zone into the continuum structure of bone cement, an example of brittle material, in investigating the mechanical behavior and fracture mechanism and to predict the fracture which elastic fracture mechanics (EFM) is unable to. Four finite element (FE) models with embedded cohesive zones for the simulations of tensile, compression, double shear and 3-point bending tests have been implemented. Cohesive zones (CZ) are embedded at high risks of fracture with orientations determined by fracture mode. A bilinear cohesive traction-separation law (TSL) is applied. The fracture parameters in traction-separation curve are validated and justified in the simulations to agree well with the force-displacement curves in the four practical tests. Apart from the maximum load, the perpetual safe working load (SWL) in theory also can be predicted by tracing the history of the stiffness degradation of fractured cohesive zone by means of simulation. A distinct advantage of our numerical model is that it is able to extend to investigate the mechanical behavior and fracture mechanism of other brittle materials. The proposed method with embedded cohesive zones in FE models can be introduced to predict the fracture and to forecast the maximum load and safe working load (SWL) of the continuum structure in more complicated loading conditions.
Abstract: In the forging sequences for support shaft, the female die in the process of backward extrusion suffered a wicked stress condition, which was responsible for a short service life. The objective of this paper is to improve the stress condition through optimizing the parameters of multi-layer die, such as the sizes stress rings and shrink-fits. The process of backward extrusion was simulated by DEFORMTM package, and then the node forces on the boundary between workpiece and die were translated into ANSYS. The ANSYS module (APDL) was applied to seek the optimal set of parameters based on the failures of the stress rings in multi-layer die at the same time. In this optimization, a two- and a three-layer dies were taken into consideration for. The optimized parameters will be used as a guideline for the practice application and the strategy used in this study can be extended to the other processes for the support shaft and other extruded products.
Abstract: The effect of electromagnetic field on the solidification structure of C90500 tin bronze (Cu-10%Sn-2%Zn in mass%) had been investigated in this paper. The results show that applying electromagnetic field during the solidification of C90500 tin bronze can refine macrostructure and δ phase, promote columnar-to-equiaxed transition, inhibit inverse segregation of Sn, and make the dendrite degenerate. The width of eutectoid structure (α-Cu+δ) becomes smaller, and the morphology of eutectoid δ changes from coarse acicular and massive shape to fine dotlike shape. The above mentioned effects become more obvious with the increasing of current intensity.
Abstract: In order to study the effects of cutting speed on a continuous miner cutting performance, set up the equations of Cantilever’s swing speed, draw graph of chips in different swing speed and rotate speed, analysis the effects of them on continuous miner cutting performance. In order to reduce the fluctuation of cutting speed and get large lump coal rate , reduce the rotate speed of drum and swing speed of cantilever as far as possible, and reduce the maximum swing angle.
Abstract: A lower-bound shakedown analysis for cylindrical shells containing defects is performed based on the static shakedown theorem in a finite element computational form. To overcome the numerical difficulties, the pseudo-temperature field is applied to a structure and the resulting thermo-elastic stress is considered as the self-equilibrium residual-stress field. The pseudo temperature is assumed as a harmonic function satisfying the uniqueness theorem, therefore the nodal temperature matrix of the whole structure can be expressed by the boundary nodal temperature matrix. The nonlinear yield condition is piece-wise linearized so that the shakedown analysis is transformed into a linear programming problem in which the strategic variable is boundary nodal temperature and objective variable is the loading multiplier. The relations of limit and shakedown pressures to geometric parameters of various defects are presented.
Abstract: The study of debonding is of importance in providing a good understanding of the bonded interfaces of dissimilar materials. The problem of debonding of an arbitrarily shaped rigid inclusion in an infinite plate with a point dislocation of thin plate bending is investigated in this paper. Herein, the point dislocation is defined with respect to the difference of the plate deflection angle. An analytical solution is obtained by using the complex stress function approach and the rational mapping function technique. In the derivation, the fundamental solutions of the stress boundary value problem are taken as the principal parts of the corresponding stress functions, and through analytical continuation, the problem of obtaining the complementary stress function is reduced to a Riemann-Hilbert problem. Without loss of generality, numerical results are calculated for a square rigid inclusion with a debonding. It is noted that the stress components are singular at the dislocation point, and a stress concentration can be found in the vicinity of the inclusion corner.