Papers by Author: Yan Liang Du

Abstract: A new method of measurement of the cable force in cable-stayed bridge model test is introduced. Pressure ring sensor is used as the main component in this method and the tension of the stay cables can be measured real-time and in time. It is vertified that this method is exact and credible by model test and can be used in actual cable-stayed bridge. The static measurements for the test model are conducted. The testing results are compared with the numerical results of finite element model developed for the test model. A platform is established for the future researchs.

Abstract: In this paper, the effect of pore structure on the chloride ions ingress into concrete was investigated. The most probable diameter was measured by Mercury intrusion porosimetry (MIP) and the total porosity was measured by evaporative water method (EWM). The results indicate that the most probable diameter by MIP has better linear relationship with chloride diffusion coefficient than the total porosity by EWM, the most probable diameter has significant influence on chloride diffusivity, and the smaller most probable diameter will lead to higher chloride penetration resistance.

Abstract: Measurement of wheel/rail contact forces is of importance. Traditional methods for wheel/rail interaction force measurement all need strain gauges on wheel sets and/or rails. Because strain gauges have the performances of zero-drift, poor anti-interference property and instability of test system, they can’t meet wheel/rail force test requirements in high-speed and heavy haul railways. A new method based on PVDF piezoelectric sensing technology is presented for the test of vertical and horizontal wheel/rail force in this paper. Firstly, based on the wheel/rail interaction characteristics, the restriction condition of track and strain sensing principle of PVDF films, principle for measuring vertical and lateral wheel/rail interaction forces is proposed. Then a series of tests were carried out to compare the performance of PVDF strain sensors with the one of strain gauges. The results show that the PVDF strain sensor has better reliability in wheel/rail force monitoring. Finally numerical analysis by Finite Element Method has been carried out to verify the feasibility of the method presented in this paper.

Abstract: A two-dimensional electromechanical analysis is performed on a transversely isotropic piezoelectric material containing an elliptical hole, which is subjected to uniform compressive forces with intensity q acting on the edge of the hole and uniform electric displacement fields at infinity. Based on the impermeable electric boundary conditions, general electromechanical fields solution are obtained in the form of complex potentials.

Abstract: A two-dimensional electromechanical analysis is performed on a transversely isotropic piezoelectric material containing a line crack of length 2a, which is subjected to uniform distributed forces with intensity q along the crack faces and uniform electric displacement fields at infinity. Based on the impermeable electric boundary conditions, the closed complex form expression for the electromechanical fields are deduced in the vicinity of the crack. Taking PZT-4 ceramic into consideration, electromechanical fields under different loads are illustrated through several examples. It can be seen that electromechanical fields show 1/2 order singularity at the crack tip, and the piezoelectric effect can’t be negelected.