Applied Mechanics and Materials Vols. 217-219

Abstract: The high strain rate compressive behavior of a bicomponent high performance epoxy resin for advanced composites filled with Polyaryletherketone (PAEK) has been studied on a modified split Hopkinson Pressure Bar (SHPB) setup under dynamic loading conditions. Dynamic stress-strain plot was obtained for each sample. The results of the study indicated that the plastic of the epoxy composites increased while yield strength decreases slightly with the increase of the content of PAEK powder. In contrast, EP/PAEK-10 composite has the best Compressive properties.

Abstract: Ni/poly(m-toluidine)(PMT) nanocomposites were prepared by in situ chemical oxidative polymerization of m-toluidine (MT) monomer in the presence of Ni powder, with ammonium persulfate (APS) as oxidant and citric acid (C₆H₈O₇) as dopant. The resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and superconducting quantum interference device magnetometer (SQUID). The results exhibited that Ni/PMT nanocomposites show a ferromagnetic behavior with saturation magnetization strength (Ms) and coercivity of 28.4emu/g and 105.8Oe at room temperature. The prepared Ni/PMT composites were soft and ferromagnetic materials. Moreover, thermal Stability of nanocomposites was also investigated.

Abstract: Using air lubricants, wear tests of Si₃N₄-hBN composites with different hexagonal boron nitride (hBN) volume fraction sliding against Si₃N₄ ceramic were carried out on a MMU-5G type pin-on-disc tester. For comparison, Si₃N₄/Si₃N₄ pairs were also tested under the same conditions. The worn surfaces of specimens were observed under scanning electron microscope (SEM). Furthermore, the wear debris were analyzed by using X-ray diffraction (XRD). Wear debris layers are formed on the wearing surface when Si₃N₄-hBN composites slide against Si₃N₄ ceramic under air lubrication. In this situation, the friction coefficients are as high as 0.80-1.20 and the wear coefficients are above 10-5 mm³/Nm for all materials tested.

Abstract: This article describes the principles and methods of evaluating DRA in the lab, then evaluate the effect of DRA in the lab by designing a DRA test loop. This is measure that thoes DRA difference concentration be provided with flow increase rate and Drag reduction rate in test loop.

Abstract: The tensile performance of the vinyl resin casting body, epoxy resin casting body, carbon fiber(CF) reinforced vinyl composites and CF/epoxy composites has been presented. The morphology of tensile fracture surface of CF/epoxy and CF/vinyl has been compared, and the interface adhesion has been analysed. The results show the tensile strength for vinyl resin casting body is lower than epoxy resin casting body’s, the tensile modulus of them are close. But the tensile strength and modulus of CF/vinyl composites are both close to CF/epoxy composites. And the vinyl has the better interface adhesion and wettability on CF than epoxy.

Abstract: This paper mainly introduces the main causes of the concrete cracks, and with Chongqing inch beach bonded port freight container terminal, drain tank letter concrete crack control as the engineering example, the paper analyzes the method of crack control. For example reduce water consumption, choose the narrow fly ash cement, reduce the narrow concrete constraint, and control the hydration heat, strengthen the concrete curing, control the steel corrosion of crack, control the box by letter of the surrounding rock deformation, they can be reached that box culverts basic don't crack effect.

Abstract: BR/MgO composites were prepared with seven kinds of particle sizes of MgO filled respectively. Effects of particle sizes on dynamic mechanical properties, vulcanization characteristics and physical properties of BR/MgO composites were studied. The results showed that the tensile strength of composites filled nanoscale of MgO was nine times of pure BR, and the vulcanization time was significantly shorter than that of composites filled with micron grade filler. The RPA experiments proved that the composites filled with MgO of 20nm and 50nm have greatly higher G＇, and that the G＇of the composites increase markedly while the value of tanδ decrease sharply with given temperature above 90 °C increasing. the higher value of tanδ at the frequency mode, and the obvious Payne effect compared with the composites filled micron grade of MgO

Abstract: Activity coefficients and concentrations of dissolved magnesium and sulfur in grain boundary are two essential parts for the calculation of the Gibbs free energy of MgS superfine inclusion in grain boundary. Activity coefficients of dissolved magnesium and sulfur in grain boundary are gained first by the use of Miedema Model and Free Volume Theory. Concentrations of dissolved magnesium and sulfur in grain boundary of Fe-matrix are gained by Mclean’s equation. At last the Gibbs free energy of MgS in grain boundary is -14.048KJ/mol in E-class ship plate steel at T=1363K. By comparing the values of the Gibbs free energy of MgS in grain boundary and that in grain interior, a conclusion can be come to that MgS superfine inclusions may form in grain boundary instead of in grain interior.

Abstract: An effective optimization method is developed for laminated composite structures using two-level optimization strategy based on Kriging model and genetic algorithm (GA). Firstly, the design of experiment (DOE) technique is used to create sample points and MSC.Nastran is employed to obtain the response (minimum weight subjected to bulking and strength constraints) of each sample point. Based on sample points and the corresponding responses, the Kriging model is formulated. Secondly, GA is performed to obtain the best thickness by optimizing the Kriging model as objective function. Then, the best stacking sequence is obtained basing on lamination parameters using GA. This paper takes a Z shape composite stiffened plate as example to verify the feasibility of the method above. The results illustrate that it can significantly save computational costs and can greatly improve the optimization efficiency.

Abstract: The strength and tensibility, elastic recovery ratio, evenness and hairiness of the pearl composite yarn were tested and compared with that of the same fineness pearl ring-spun yarn. It is concluded that the strength, elastic recovery and evenness of pearl composite yarn is superior to that of the ring- spun pearl yarn, thick spot or slub number per kilometer 1-8mm of hairiness index of pearl fiber composite yarn are lower than that of the pearl ring- spun yarn.