An Analytical Anisotropic Model to Analyze Fiber Reinforced Polymer Bolted Flange Joints

Fiber Reinforce Plastic composite flanges have recently experienced a spectacular development in the area of pressure vessels and piping. The current procedures used for the design of these flanges are a major concern because of their inappropriateness to address the anisotropic behavior of composite materials. The current ASME code design procedure of composite flanges of section X uses the same analytical method as the one of section VIII division 2 which treat the flanges as isotropic materials such as metallic flanges. This study deals with FRP bolted flange joints integrity and bolt tightness. A new developed analytical FRP model that treats anisotropic flanges with and without a hub is presented. The model is based on the anisotropy and a flexibility analysis of all joint elements including the gasket, bolts and flanges. It is supported experimentally with tests conducted on a real NPS 3 class 150 FRP bolted flange. Furthermore, three different numerical models based on 3D anisotropic layered shell and solid element models were conducted to further compare and verify the results obtained from the new developed analytical approach. The results show that the new model has potential to be used as an alternative tool to FEM if an accurate method to analyses the stresses and deformation of problematic FRP bolted joint applications.

Experimental Studies on Damages to FRP Reinforce Bridges under the Effect of Limited Overload

On the basis of experimental studies on the bending resistance of FRP reinforce bridges under the effect of limited overload with high preloading amplitude values, the relationship between FRP amounts and ultimate loads is analyzed and influences of limited overload on flexural strength, deflection, crack width and height of bridges are fatherly studied. Thus damage effect rules of FRP reinforce bridges are concluded which provide scientific technology supports for the application of fiber reinforce plastic on bridge reinforcement.

Nonlinear Analysis of FRP SRC Concrete Beams

On the basis of the theory of FRP sheet steel reinforcing concrete beams (SRC-beams), in order to better explore the force performance of FRP (Fiber Reinforce Plastic) steel reinforcing concrete beams, this paper analyzes the stress process simulation of the beam using the computer program of nonlinear analysis. In order to validate the program of the beam section the reliability of the simulation analysis, this paper brings beam section size and its material performance parameters into program and gets different parameters on the bearing capacity of beams influence law. Research shows that when working in the stage of FRP elasticity the reinforcement of FRP layers has little influence on bend curvature figure. In the elastic-plastic stage it has larger influence and the cure increases with the increase of FRP reinforcement layer. It shows that with the increase of the section stiffness beam bending flexural capacity is also bigger.

DELAMINATION MONITORING OF QUASI-ISOTROPIC CFRP LAMINATE USING ELECTRIC POTENTIAL CHANGE METHOD

Real-time detection of delamination in carbon fiber reinforce plastic (CFRP) laminates has been requiring to maintain the structural reliability of aircraft. In this paper, electric potential change method (EPCM) was applied to monitor delaminations in quasi-isotropic CFRP laminate. As the coefficient of thermal expansion and mold shrinkage factor of carbon fiber and epoxy matrix is different, residual stress is developed in the laminate during the fabrication process of curing. The local strain variation due to delaminations was measured by EPCM utilizing the piezoresistivity of the laminate itself. Finite element simulation was performed to investigate the applicability of the method.