Papers by Author: Zhen Qing Wang

Abstract: Fiber impregnation has been the main obstacle for thermoplastic matrix with high viscosity. This problem could be surmounted by adapting low viscous polymeric precursors Woven basalt fabric reinforced poly (butylenes terephthalate) composites were produced via in-situ polymerization at T=210°C. Before polymerization, catalyst was introduced to the reinforcement surface with different concentration. DSC is used to determine the polymerization and crystallization. SEM is used to detect whether the catalyst existed on surface. Both flexural and short-beam shear test are employed to study the corresponding mechanical properties.

Abstract: The stress and strain field near the tip of Mode I growing crack in materials under creep conditions is examined. The case of the effective stress equal to zero is considered. The asymptotic equations for the crack of the crack tip field are derived and solved numerically. It is concluded that the rates of stress and strain posses the r^δ-1 singularity near the tip crack, and the stresses remain finite at the crack tip.

Abstract: Shear connectors are usually used to connect two different structural materials and to transfer longitudinal shear forces across the materials interface in composite structures. This paper presents an experimental study on the behavior of shear connectors in UHPFRC-NSC composite structure. A new experimental installation (The NSC block is laid on the supporting deck, and the higher UHPFRC block is cantilever, meanwhile the top side of the NSC block is constrained.) is applied. A modified formula that it is proposed to calculate the load carrying capacity of shear connector is given. The experimental results are in good agreement with the calculated results.

Abstract: Based on Zwick/Roell,this paper had carried on flexural experiments of epoxy resin filled with nano-silica particles, obtaining related mechanical properties.Microstructures of nanocomposites were analyzed by scanning electron microscopy (SEM) in the meanwhile. The flexural experiments revealed that nano- silica particles strengthened epoxy resin very well, and flexural modulus of modified matrices rised due to rigid silica particles, compared with pure epoxy matrices. Flexural strengths of epoxies modified by silica nanoparticles improved significantly.

Abstract: This paper presents compressive and tensile constitutive law of UHPFRC used in numerical simulation. UHPFRC exhibits different constitutive law from normal and high strength concrete. A multi-directional fixed crack criterion that considers tensile strain hardening is defined to describe tensile behavior, and Drucker-Prager criterion with an associate d flow rule is adopted in the compressive region. The comparison of numerical results with experimental results indicates a good agreement.

Abstract: After boundary conditions of member and thermal parameters of materials are determined, ANSYS software is utilized to analyze the maximum temperature distribution in the member under different fire duration. The equivalent cross-section economization method is given to calculate residual bearing capacity of RC member after exposure to high temperature, here, strength of reinforcement is considered as invariant, and the original section area is regarded as reduced. The numerical results are in good agreement with the experiment results of other reference, so appliance of the method is proved, Based on these, some parameters have significant influences on reduced coefficient of residual bearing capacity, such as sectional dimension, fire duration time, strength of reinforcement and concrete，ratio of reinforcement，thickness of fire-protection layer, which are analyzed and theory basis is supplied on safe monitor, repair and reinforcement of RC member after exposure to high temperature.

Abstract: In this paper, the influence of geometrical parameters on failure load of bolted single-lap composite joint was investigated. The composite laminate was manufactured from HTA/6376, a high-strength carbon fiber–epoxy material currently used in primary structures in the European aircraft industry. Two geometrical parameters which were plate width-to-hole diameter ratio (W/D), and the edge-to-hole diameter ratio (E/D) were analyzed. To avoid modeling each ply of the laminates discretely, the laminates were modeled using equivalent linear elastic properties. the failure analysis was modeled by Extend Finite Element Method (XFEM) in ABAQUS. Maximum principal stress criterion (Maxps) was used to determine the failure load.

Abstract: Shape memory alloy (SMA) reinforced composites have been widely used in aerospace engineering fields. In this paper, four basic assumptions were presented to simply the research model based on the Eshelby’s equivalent inclusion method and Mori-Tanaka scheme. Based on the three-phase equivalent system and two-step equivalent process, the effective elastic modulus and thermal expansion coefficient of unidirectional random distribution short SMA fiber reinforced composites were derived. The tensile mechanical properties of composites with fiber volume fraction (15%), size (L=3, D=1; L=5, D=1), and number (N= 30, 50), were simulated using software ANSYS12.0, and discussed the failure mode of the composites.

Abstract: Composite materials have excellent mechanical properties and can be mechanically tailor designed, so the composite materials are widely used in civil engineering and structural system such as aerospace and shipbuilding industry. Numerous studies show that the damage of joints is main reason which results in composite structure failure. In this paper, extended finite element method (XFEM) is applied to investigate the failure load prediction of bolted single-lap composite joint. The influences of geometric parameter: edge-to-diameter (E/D) on failure load is investigated.

Abstract: Construction control is the key technique for cable dome. During the actual engineering, however, it is difficult to ensure no difference between the real prestress distribution and the designed value due to existed construction errors. The practical problem for cable dome construction is to determine how much is allowable errors limit. To solve the problem, sensitivity analysis of manufacture errors of bearing and cable length are carried out in this paper. The random errors are simulated by Monte Carlo method. In a numerical model of cable dome with the diameter of 62m, the sensitivity of effect of bearing and cable length manufacture errors on structural performance is analyzed. Numerical results show that the manufacture errors of radial bearing, hoop cable 2, ridge cable 3, diagonal cable 3 and hoop cable 1 should be strictly controlled. Besides, the maximum allowable errors are proposed referring to the domestic existing specifications.