Applied Mechanics and Materials Vols. 117-119

Abstract: The microcellular foaming PP/GF composites was made under the condition of twice-open mold by using chemical foaming injection method, according to glass fiber reinforced mechanism, the effect rule of GF on mechanics properties was studied in microcellular foam PP composites. The results showed that tensile and impact strength of Micro-foam PP/GF composites by one-step method were higher than that of micro-foam PP/GF composites by two-step method, when the content of GF is 30%, the tensile and impact strength of micro-foam PP/GF composites by one-step method can reach 55.72MPa and 7.5kJ/m² respectively，one-step method can get higher strength and higher toughness micro-foam PP/GF composites.

Abstract: Abstract: The section of diversion penstock near the powerhouse behind dam in some hydropower station is equipped with expansion joints, which is used to remedy deformation of penstock in axial and lateral due to the variation of temperature and foundation subsidence. When the hydropower station is in normal water diversion and power generation, the discharged flow generates fluctuating loads, induces structural vibration of guide cylinder of expansion joints, gives rise to cumulative fatigue damage of guide cylinder and also leads to weld joints in guide cylinder cracking to fall off. When generating unit is in the condition of load rejection, expansion joints bears not only the fluctuating pressure loads of the flow, but also undergoes the shock from water-hammer pressure as well, so this demands higher requirement for the safety and reliability of expansion joints structure. It has important engineering value for ensuring safety and reliability of water-diverting power generating system to conduct researches on dynamic effect that fluctuating loads having on expansion joints guide cylinder structure and cumulative fatigue damage of terminal weld of guide cylinder

Abstract: Liquidus temperature, electrical conductivity and phase composition of Al₂O₃ -CaO-CaF₂ slag system were studied. The results showed that the liquidus temperature of the slag decreased with increasing CaF₂ content, and its electrical conductivity increased with increasing CaF₂ content and temperature. The liquidus temperature is 1468°C when the content of CaF₂ is 20%. Its phase composition are composed of CaAl₂O₄、Ca₂Al₃O₆F、Ca₂AlF₇ andAlF₃. When the content of CaF₂ is 10%, there are lots of CaAl₂O₄. The content of CaAl₂O₄ decreased with increasing CaF₂, but the content of Ca₂Al₃O₆F and Ca₂AlF₇ increased.

Abstract: Due to the virtue in energy consumption, response time and work reliability, the magneto-rheological (MR) damper is a new promising devices for vibration control, in which the controller input expected control force and piston velocity to justify MR damper input voltage, so that desired damper force is achieved. It follows that the functional relationship between input voltage, expected control force and piston velocity is important for MR damper application. In this paper, a novel simplified and high-precision inverse dynamics model is derived based on MR damper Bouc-Wen phenomenological model, by which the input voltage of MR damper is calculated by means of expected control force and piston velocity. To verify the validity of this proposed inverse dynamics model, two numerical simulations of MR damper force following tests are introduced in the latter of this paper.

Abstract: A fluid-solid interaction FEM of entire hydraulic mount of vehicular engine are presented. The dynamic response of the hydraulic mount is simulated. By means of the simulated result of the mount transient response in time domain, the dynamic performance and transmissibility of the hydraulic mounts are calculated. the ALE method transforming reference frames is used to resolve the problem the reference frame of hydro-dynamical questions is different from the reference frame of structural questions.

Abstract: A numerical simulation model which describes the ice-cone interaction process is presented. The model is based on the field observation which was made on the prototype platform named JZ20-2 MUQ. The dynamic numerical simulations are performed by using the LS-DYNA program and the present model. The failure evolutionary processes are analyzed between ice and conical shaped structure according to the stress distributions in the ice sheet. The distributions of the ice energy and contact force during the ice-cone interaction are also presented. The numerical results indicate that the present model and the modeling method are validated and reliable in describing the dynamic processes of the ice-cone interactions. Furthermore, the results could also provide the references for the ice resistant design of conical structure.

Abstract: Many RC frame structures were severely damaged or collapsed in some layer. The phenomenon was significantly different from the expected failure mode in seismic design code. This paper comprehensively sums up the earthquake characteristics of masonry infilled RC frame structures. Based on an investigation of a masonry infilled RC frame structure damaged in the earthquake area, conduct the research on frail-layer caused by infill walls uneven decorated. On the hypothesis of keeping the main load-bearing component invariant, two models were considered, i. e. frame with floor slab, and frame with both floor slab and infill wall. Furthermore, divide them into groups of the bottom, the middle and the top frail-layer to discuss by changing the arrange of infill wall. Time history analyses using three-dimensional sophisticated finite element method were conducted. The major findings are: 1)infill walls may significantly alter the failure mechanism of the RC frames. 2)controlling the initial interlayers lateral stiffness ratio in a reasonable range is an effective method to avoid frail-layer damage. These findings suggest that the effects of infill wall should be considered in seismic design, keep the initial interlayers lateral stiffness ratio less than the paper suggested, and the structural elasto-plastic analysis model should take slabs and infill walls into account.

Abstract: The stability of a supported cylinder subjected to axial flow is studied numerically. The dynamics of the cylinder is investigated with the numerical method applying the new nonlinear model in witch the nonlinear terms considered are the quadratic viscous force and the structural nonlinear force induced by the lateral motions of the cylinder. Using three-mode discretized equation, numerical simulations are carried out for the dynamical behavior of the cylinder. Some integration terms that appear in the discretization of the equation and can not be expressed in an analytical form are calculated using a numerical method. The results of numerical analysis show that at certain value of flow velocity the system loses stability by divergence and at a higher velocity the flutter around the zero equilibrium may occur. There is some region in witch three different motions (configurations) can take place at the same parameter values.

Abstract: In penetration problems, the heterogeneity of the concrete would affect the ballistic responses. The presented paper studied the influence by numerical method. During the analysis, the concrete was defined as “numerical concrete”, which was composed with different size aggregates randomly included in the mortar. In the numerical concrete, the ITZ (interfacial transition zone) was replaced with the connected strength (tensile strength and shear strength). Based on the validation of the mesh, the ballistic responses were studied. From the study, it was concluded that: the randomly-distributed aggregates affected the stress symmetry which changed the missile trace, which couldn’t be alternated by concrete in the homogeneous model, and that the residual velocity of the missile decreased with the increase of the connected strength of the interfaces.

Abstract: Based on the principles of heat transfer, finite difference method was adopted to develop program of calculating thermal crown of single-stand irreversible foil mill. The temperature distribution and thermal crown of roll were calculated for one rolling schedule. The temperature of each layer calculated was analyzed. The computed and measured surface temperature was compared, which shows good consistence with each other. The law of thermal crown changes with time conformed to practical account.