Applied Mechanics and Materials Vols. 166-169

Abstract: Polyester textile is widely adopted in ordinary engineering applications where mechanical properties like high strength and relatively good plasticity are demanded at the same time. Though there has been some research on the change to its mechanical behavior in corrosive environments to study the effects of corrosion, for example, the ultraviolet (UV) light, the influence of corrosive media like ozone gas (O3) on its mechanical properties is rarely explored up to now. Here fabric made of polyester fibers is chosen to study the possible influence of ozone gas with extremely high concentration in the tensile strength as well as the failure behavior of this material. The aim of this research is at extending or expanding the application of polyester fabric to wider engineering areas through the study of the influence of extreme environment conditions in the mechanical properties of polyester fabric and the failure mechanism as well.

Abstract: A class of backward doubly stochastic differential equations are studied. We obtain a comparison theorem of these multi-dimensional backward doubly stochastic differential equations.

Abstract: Prestressed concrete cylinder pipe(PCCP) has been applied to oil, water conservancy and hydropower engineering and other fields as a kind of high quality composite pipe. Because of its complicated structure and work condition, mechanical behavior of PCCP is not uniform. In this paper, the mechanical model is established in PCCP working stage based on the elastic plane strain theory of axisymmetric multilayer cylinders and the mechanism of the ring-like strands action. Then the design method of prestressing is put forward according to the aim at the crack control. The stress is analyzed with finite-element analysis in the condition of different pressure, and also the method is amended compared with the finite-element analysis. It is indicated that the design method of prestressing is reasonable compared with specification of both domestic and international.

Abstract: A coupled elastoplastic damage model is proposed for the description of anisotropic concrete under compression-dominated stresses. The model is applied to typical concrete in various loading conditions. Damage evolution law and plastic damage coupling are described by using the framework of irreversible thermodynamics.

Abstract: Due to the independence of physical domain and the mathematical cover system, the numerical manifold method (NMM) can efficiently simulate crack propagation without remeshing. At the same time, the polygonal elements are also very attractive due to their great flexibility in meshing and high efficiency in materials modeling. In the present paper, the NMM is applied to solve 2-D crack propagation problems on polygonal elements. Our numerical results show that the proposed method can well capture the crack growth trajectory compared with the reference solution

Abstract: The Camassa-Holm and Degasperis-Procesi equation describing unidirectional nonlinear dispersive waves in shallow water is reconsidered by using an auxiliary elliptic equation method. Detailed analysis of evolution solutions of the equation is presented. Some entirely new periodic-soliton solutions, include Jacobi elliptic function solutions, hyperbolic solutions and trigonal solutions, are obtained. The employed auxiliary elliptic equation method is powerful and can be also applied to solve other nonlinear differential equations. This method adds a new route to explore evolution solutions of nonlinear differential equation.

Abstract: In order to research the interface bond-slip behaviors of recycled aggregate concrete-filled square steel tube (RACFSST), ten specimens using waste concrete were designed for launch test. The three changing parameters were concrete strength grade, embedded length and recycled coarse aggregate replacement rate. The load–slip curves of square steel tubes and recycled aggregate concrete were obtained, and starting bond strength and ultimate bond strength influenced by each changing parameter were analyzed. The results show that the replacement rate had a slight influence on the starting bond strength and ultimate bond strength, while the embedded length had the opposite effect. The shorter embedded length specimens had larger bond strength. The concrete strength had a relatively large influence on them.

Abstract: Partial interaction between two different materials of composite beam is consequent from longitudinal slip and transverse uplift effects at interfacial surface. The behaviour has yielded higher order differential equation as compared to beam that interacts fully. In this paper, a meshless approach for the analysis of composite beam with partial interaction by Element Free Galerkin (EFG) method is formulated and investigated. Discretized solely by nodes, the Moving Least Square (MLS) method is adopted for the EFG shape functions formulation and the variational approach is chosen in developing its Galerkin weak form. The weak form essential boundary conditions are enforced by Lagrange multiplier, where comparable results are obtained between developed EFG code and established analytical solutions. In addition, influence of various weight functions on shape function smoothness of EFG code is explored.

Abstract: In this paper, an integrated approach is presented to localize and assess the severity of damage in composite plate. Modal analysis was performed to obtain the mode shapes from both experimental and finite element analysis results. The mode shapes were then used to calculate an improved damage indicator function to localize damaged area. The presented method takes the change rates according to certain diagonal elements of the damaged structure flexibility matrix as identification indicator. The localization property of the indicator with respect to the damage factors makes it easy to identify the damage of multi-span beam and plate structures. An inverse optimization procedure is employed to minimize a no-linear error function between the analytical and measured modal parameters. The main problem is the multiplicity of parameter estimation solutions arising from using spatially sparse and noised-polluted data. A variable-weight optimization is used based on the alterability of the error function composition. Some examples have been utilized to numerically demonstrate the effectiveness of the present identification approach.

Abstract: Comparisons of AR model and wavelet analysis model are presented. Similarities and differences between the two models are firstly indicated with respect to its mathematic expression and physical meaning. Furthermore, range of frequency domain characterized by samples, length of samples and algorithms of models, accuracy and efficiency are also discussed. This can be used as reference to choose model reasonably in the application of wind field simulation.