Applied Mechanics and Materials Vols. 117-119

Abstract: In high strength pipeline steel rolling technology, the control of final cooling temperature of different microstructure, different microstructure of pipeline steel tensile strength, yield strength and the effects of different, thus determine its yield ratio differences. The results show that with lath bainite microstructure of the pipeline steel than with acicular ferrite microstructure of the pipeline steel with lower yield ratio, at the same time lath bainite microstructure in small dispersed precipitates in pipeline steel X80 pipeline steel to reduce the yield ratio is beneficial, for high strength pipeline steel production technology to provide the theory basis.

Abstract: This study explores a series of optical, physical and structural properties based on P₂O₅-Al₂O₃-ZnO (ZAP) with glass doped 1 mol% Tb₂O₃, which changed the composition ratio between ZnO and P2O5. The structure and optical of glasses were studies by Raman spectra and fluorescence spectra. The Raman spectra with the zinc content increases, the 650-810 cm^-1 at the P-­O­-P bond has no shift, but the intensity of the absorption peak decreased. The fluorescence intensity increases with the ZnO content increases. The glass density and refractive index also increases with the ZnO content increases.

Abstract: This paper puts forward a method to calculate the natural frequencies and the mode functions of in-plane bending vibration of the ring-beam. The combined ring-beam is separated into two independent structures—a ring and a beam. Through the continuity conditions, two independent structures are coupled. This paper gives the bending vibration mode functions of the beam and in-plane bending vibration mode functions of the ring, and analyzes the effect of the structural parameters on the natural frequencies sensitivity.

Abstract: Abstract. It is difficult to seek an optimization design for the falling object protective structure (FOPS) of wheel loader cab. Focusing on this problem, we discuss the topology optimization with SIMP theory under impact condition and the designing parameters, response function and constrain conditions are confirmed. The proposed method is applied to wheel loader cab to get a topology structure. The numerical analysis indicate that the optimized design of wheel loader cab has light weight and can provide sufficient protect for the operator.

Abstract: By building a finite element model of a special-shaped arch bridge, this paper discusses the effects of the changes of the geometric shape, and the skewed angle of the girder and arch on the dynamic characteristics. In addition, this paper analyzes the longitudinal earthquake responses using the response spectrum method. The results show that when longitudinal earthquakes occur, all geometric shapes, and skewed angles of the girder and arch exhibit different levels of effect on the horizontal and vertical deformations of the girder and the arch, the internal forces of the arch, the girder, and the cables. Among all these parts of the bridge, the arch is affected most by the aforementioned factors. Moreover, because of the unique geometric shape of the special-shaped arch bridge, the distributions of initial and completed cable forces are complex. Therefore, obtaining regular stress responses from the special-shaped arch bridge is difficult regardless of whether the bridge is in-plane or out-of-plane. Hence, the arrangement of cable forces should be specifically considered when building an analytic model of a special-shaped arch bridge.

Abstract: In this study, calcium nitrate(Ca(NO₃)₂•4H₂O) and phosphorus pentoxide(P₂O₅) were used as precursor to prepare hydroxyapatite(HA) layer by sol-gel method, followed by a dipping-coating method to coat HA layer onto Ti. Phase formation and microstructure were investigated by XRD and SEM to study the influence of atmosphere on the property of HA layer. The results revealed that there exists no large cracks in the layer which was heated in the nitrogen, leading to a good surface quality compared with the layer which was heated in the air. And there is no obvious difference in crystallinity and volume fraction of HA in the layer when adopting heat treatment in different atmospheres.

Abstract: This paper gives a detailed study of temperature distribution on Ti46Al0.5W0.5Si alloy directionally solidified by cold crucible. Based on experiment and numerical calculation, the heating process under different power was investigated, and the operating efficiency of cold crucible was roughly calculated. Further, the temperature field of Ti46Al0.5W0.5Si alloy under high power was numerically calculated, the finite element model predicted the temperature distribution at different moment. The results give a significance guide on cold crucible directional solidification.

Abstract: The main goal of present paper is to construct an efficient reduced order model (ROM) for aerodynamic system modeling. Proper Orthogonal Decomposition (POD) is presented to address the problem. First, the snapshots are collected to form the POD kernel, and then Singular Values Decomposition (SVD) is used to obtain POD modes, finally POD-ROM can be constructed by projecting full order aerodynamic system to POD modes subspace. However, the robustness of ROM constructed via conventional POD method is not guaranteed. To improve the robustness of conventional POD method, balanced truncation modification was introduced. Aero-elastic active control case was chosen for this new method validation. The results demonstrate POD method with balanced modification is efficient and accurate enough for aeroelastic system analysis.

Abstract: The influences of noise on chaotic dynamics in a vibro-impact oscillator, modeled as Duffing Van der Pol (DVP) system with unilateral rigid barrier, are investigated. An interpolation strategy is introduced to locate the impact instants, and effective numerical method is proposed to improve the computational precision in the vibro-impact oscillator. Near the boundary crisis, the phenomenon of noise-induced chaotic transition occurs. Our studies reveal that the escape of oscillator from the boundary is responsible for this chaotic transition. The increase of noise can aggravate this escape.

Abstract: In order to simulate the elastic-plastic behavior of concrete better, an effective curve fitting method is employed to find the constitutive function based on Legendre orthogonal polynomial and least square method. And a new numerical analysis program using arch-length method to deal with nonlinear problem is designed. The most important consequence is that not only the fitting function, but also its derivative function and its definite integral are recursive. The fitting curve given by new method is applied in numerical analyzing. Cube model is examined under uniaxial compressing with completely restricted boundary conditions. The results show convex deformation and the damage on oblique section clearly. Compared with those piecewise fitting functions, the Legendre orthogonal polynomial fitting function obtained can be introduced into the nonlinear harden-soften character of concrete constitute law more convenient because of its uniform function form and continuous derived feature. And the fitting idea by orthogonal base function will provide a widely road for studying the constitute law of concrete material.