Applied Mechanics and Materials Vols. 117-119

Abstract: This article introduces interval factors involved in material mechanics, and it also has many problems of interval parameters. Compressive rod stability design will be taken as an example to discuss interval analysis processing method; it explains not only the necessity for material mechanics and engineering design to lead into the interval analysis method, but also the specific application of it.

Abstract: A numerical test code named RFPA (Realistic Failure Process Analysis) was used to investigate the stress filed transformation process of the reinforced concrete specimen under uniaxial tensile loading. The periodically distributed fracture spacing phenomenon exists in the reinforced concrete structure and the concrete cover thickness was an important factor influence the average crack spacing and crack number. The numerical simulation results show that the stress fields on the concrete between the two adjacent cracks go through a variation process from tensile stress to compressive stress with the increasing of the concrete cover thickness value. It is clear that the stress distribution and fracture spacing were related to the concrete cover thickness under the condition that the materials characteristics were certain (such as concrete and reinforcement materials).In addition, if there was a new crack produced, the location was sure in the middle of the two adjacent cracks since the maximum stress occurred in the middle of the two adjacent cracks. So, it indicates that the concrete cover thickness can influence the average fracture spacing and the crack number in the reinforced concrete prism specimen.

Abstract: The Seismic excitation mode has been the hot and difficult topic both in engineering and academic field. This paper mainly discussed the excitation direction and the combination of excitation direction of ground motion, comparatively analyzed seismic response in four excitation mode, which including the single-track one-point incentive, single-track multi-point incentive, much-track one-point incentive, and much-track multi-point incentive, with specific project examples of large-span continuous rigid frame bridge, and get the corresponding conclusions.

Abstract: In order to systematically study on dynamic mechanics character of granite, impact compression experiments and impact flattened Brazilian disc specimens of granite have been investigated with modified split Hopkinson pressure bar (SHPB) experimental facility, curve about stress versus strain and other parameter at strain rates of 23.9/s～108.4/s were obtained from impact compression. The dynamic tensile strength and critical tensile failure strain at strain rates of 2.3/s～25.6/s were obtained from impact flattened Brazilian. The experimental result show that dynamic compression strength , elastic modulus and failure strain，dynamic tensile strength significantly increase comparing to quasi-static experiment, and the above mechanics parameter include dynamic strength etc will increase with strain rate increasing, granite have the character of impact harding and ductility enhancement. The failure degree of failure will increase with increasing strain rate under impact compression; the failure configurations of the specimens present an center splitting mode under impact flattened Brazilian experiments. Whether impact compression or impact splitting under strain rate including this paper ’s experiments, the relationship between the DIFC or DIFT and the logarithm of strain rate is linear.

Abstract: In order to obtain the Lower Muscle Strength Feature for Elite Speed Skaters in High Speed Gliding, this paper applied video analysis and isokinetic testing methods to conduct kinematic and kinetics dates. Contrasting to the kinematics dates, torques were computed by the Newton interpolation polynomial, which are simulated as the actual moments during gliding. According to the experimental results, the sLower Muscle Strength Feature is unique and correct.The larger of the velocity, the less moments produced from the hip, knee and ankle muscular, which will do harm to the power output.

Abstract: Based on the experimental and FEM analysis, it was discussed that the stress balance was not a necessary condition for determining rock dynamic fracture toughness accurately using holed-cracked flattened Brazilian disc. The dynamic stress distribution modes of disc sample with time change were analyzed from the early loading stage to continued loading process. It was proved that the fracture time may occur before the balance of stress was achieved. It was not necessary meet the condition of the stress balance using the experiment combined with numerical method. We could get dynamic fracture toughness, according to the dynamic stress intensity factor of the crack tip and fracture time.

Abstract: As a surface technology, electroless plating is applied to almost every industry branch. To improve the wettability of SiC powder and metal, the surface of SiC powders was plated with a Ni plating in the basic solution according to the reaction theory of electroless plating. The main salting was nickel chloride, and the reducing agent was hydrazine hydrate. The plating velocity, phase transformation and microstructurewere investigated using XRD and SEM. The results show that the SiC powders had no increasing weight and no reaction can occur when the pH below 8.5. when the pH value was between 10 and 11, the weight gain of powders closed to the theoretical value, the Ni peaks in X-ray diffraction patterns of powders was relatively strong, the SiC coating surface was composed of granular, cellular and globe-like Ni, the substrate was covered of Ni plating completely. When the pH value was above 11, the gas production was becoming more pronounced and the reaction speed increasing with the increased of the pH value, the time from deep blue to colorless of solution started to drop off, the Ni(OH)₂ peaks in X-ray diffraction patterns of powders have already begun to emerged and a small amount of nickel films was generated.

Abstract: In this work, Fe-Zn coating on copper is obtained by electroless plating. The surface mor -phologies and composition of the coatings has been investigated using scanning electronic microscope (SEM) and energy dispersive spectroscopy(EDS). Corrosion behavior of Fe-Zn coating in3.5% NaCl solution is gaved a further insight. The impedance diagram indicates that corrosion resistance of coating is better. The open circuit potential of Fe-Zn coating is at about -1V. Self-corrosion potential of Fe-Zn coating in 3.5%NaCl solution shifts in the positive direction first and then shifts from -0.622V to -0.603V with increasing heat-treated temperature, while corresponding self-corrosion current decreases at first and then. increases Corrosion resistance of coating is the best when heat-treated temperature is 300°C.

Abstract: In this paper a vibration isolation mass structure with composite braces is proposed to reduce noise and vibration transmission through the hull and internals of a double cylindrical shell. Influence of the various complicating effects such as vibration isolation mass’s cross section size or the layout location on the vibration isolation performance of composite braces structure are discussed. Besides, we also provide a composite structure form with high transmission loss due to the theory of vibration insulation of isolation mass and noise reduction of damping material. Study shows that composite braces structure combined the appropriate vibration isolation mass with viscoelastic material can effectively decrease the hull vibration and sound radiation in the mid-high frequency domain, which can significantly attenuate transmission of the plate flexural wave.

Abstract: New results of buckling and postbuckling analysis are presented for a shear deformable anisotropic laminated cylindrical shell of finite length subjected to torsion. The governing equations are based on a higher order shear deformation shell theory with von Kármán-Donnell-type of kinematic nonlinearity and including the extension/twist, extension/flexural and flexural/twist couplings. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling response of perfect and imperfect, moderately thick, anisotropic laminated cylindrical shells with different values of shell parameters and stacking sequence. The postbuckling equilibrium path is unstable for a moderately thick laminated cylindrical shell under torsion and the shell structure is virtually imperfection-sensitive.