Mechanical response of anchored FRP bonded joints: A nonlinear analytical approach (original) (raw)
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Axial/Bending Coupled Analysis for FRP Adhesive Lap Joints
Mechanics of Advanced Materials and Structures, 2010
ABSTRACT In this paper a finite element analysis of the behavior of adhesive joints between FRP (fiber-reinforced polymers) adherents is presented. In particular, double-lap joints, in the case of both normal and shear/flexure stresses, are considered. The problem is nonlinear due to the mathematical formulation of the cohesive laws introduced to model the interfacial interactions. On the contrary, the adherents are supposed to be linear elastic up to failure.The common approach of analyzing shear/flexure behavior separately from extensional behavior, as well as disregarding the mutual effects between the normal and tangential stresses acting at the joint interfaces, has been updated. The paper takes into account the coupling effects between shear/flexure and extensional equilibrium problems. As highlighted in literature, only a coupled analysis can be considered correct when the mechanical characteristics of the adherents are quite different, as usually occurs in practice. Furthermore it also has been assumed that the adherents are shear deformable.The numerical results obtained by such an approach are presented, discussed and compared with others available in literature.
Strength assessment of adhesive-bonded joints
Computational Materials Science, 2008
This paper deals with non-linear analyses of adhesively bonded joints under tensile lap shear loading. 3D FEM models are taken into account. The effect of the number of elements through the adhesive layer thickness is considered. Tensile true stress-true strain curves are used as models of the adherend and adhesive materials. The single lap joints are tested to validated the numerical analyses. Comparison between one-step and two-step loading is considered. In the two-step loading, a uniform displacement in the transversal direction in the one grip region is applied, followed by a tensile loading. The uniaxial load is applied gradually until the joint fails due to large plastic deformation. Non-linear analyses and laboratory tests were performed for two different adhesive thickness (0.2 and 0.03 mm). The results of laboratory tests are complied with the results of finite element simulations. The authors offer method which will be used to modelling the steel-composite bonded structure subjected to multiaxial loads.
Mechanical behaviour of FRP adhesive joints: A theoretical model
Composites Part B: Engineering, 2009
ABSTRACT In this paper a mathematical model for studying the equilibrium problem of adhesive joints between FRP adherents is presented. In particular, double and single-lap joints, both in the case of normal and shear/flexure stresses are considered. The problem is non linear due to the cohesive constitutive law adopted for modeling the interface. On the contrary, the adherents are supposed to be indefinitely linear elastic.The possibility to uncouple the problem of shear/flexure from the extensional one, as well as disregard the mutual effects between the normal and tangential stresses acting at the joint interfaces is also assumed. As highlighted in literature, this hypothesis allows results which are sufficiently correct from a technical perspective when the mechanical characteristics of the adherents are almost the same, as supposed in the present paper. Within such a framework it is possible to trace back the examined equilibrium problems to those of simpler auxiliary structural schemes. A simple and efficient iterative procedure for solving the aforementioned problems is also proposed.
Ultimate behaviour of adhesively bonded FRP lap joints
2009
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Composite Structures, 2015
Nowadays fiber reinforced polymer (FRP) composites play an important role in the strengthening of structures. Different methods can be used to apply these materials: the externally bonded reinforcement (EBR), and the near surface mounted (NSM) using strips and NSM rods. There are only a few studies comparing these methods or presenting an efficient model to simulate these strengthening techniques. This study looks mainly at the analysis of the interface between FRP-to-parent material bonded joints. The paper examines, through a new discrete model based on axial and shear springs, the performance of FRP-to-parent material bonded joints for EBR or NSM techniques using strips or composite rods. In order to implement the model a routine in MATLAB was developed and several bond-slip curves were assumed. The results revealed that load-slip curves or bond stresses, strains or slippages along the bonded length obtained from several bond-slip curves are similar to the analytical and other numerical solutions found in literature. In what concerns the adhesion between two different materials, and assuming the same bond characteristics for the three fiber strengthening techniques, the NSM system using FRP strips had the highest maximum load transmitted to the FRP strip combined with the lowest effective bond length. The results obtained from the proposed model were also very accurate with that obtained from an analytical solution found in literature that simulates the debonding phenomenon of FRP-to-concrete interfaces between to adjacent cracks.