Moslem Shahverdi

Mode I fatigue and fracture behavior of adhesively-bonded pultruded glass fiber-reinforced polymer (GFRP) composite joints

The fatigue/fracture behavior of adhesively-bonded pultruded glass fiber-reinforced polymer (GFRP) joints is significantly affected by the loading ratio. This effect is analyzed in this chapter through a complete fatigue/fracture database, derived during recent years, and correlated with the exhibited failure processes of the examined joints. A phenomenologically based criterion is then used for the simulation of the exhibited behavior and the prediction of the fatigue/fracture behavior of the examined joints under different loading conditions. It is shown in this chapter that, upon accurate estimation of the model parameters, it is possible to reliably predict fatigue crack growth curves for several unknown loading conditions, thereby assisting the development of methodologies for the fatigue life prediction of joints under realistic loading conditions.

Analytical model of asymmetrical mixed-mode bending test of adhesively bonded GFRP joint

This paper presents new analytical model of asymmetric mixed-mode bending (MMB) specimen of adhesively bonded pultruded GFRP joints. An easily applicable relationship for the calculation of the strain energy release rate of the asymmetric MMB specimens is proposed based on the beam theory. The model is capable to analyze stacking sequence as well as various crack propagation paths. In the paper the effect of the various fiber bridging length and different crack propagation paths is analyzed analytically and supported by experimental results. The methodology and results presented in this paper could be utilized for the design of both joint geometry and lay-up of the laminates constituting the joint or for the prediction of the fracture behavior of such structures.

Mixed-mode fatigue and fracture behavior of adhesively-bonded composite joints

The mixed-mode fatigue and fracture behaviors of adhesively-bonded pultruded glass fiber-reinforced polymer joints are presented in this chapter. These behaviors are based on experimental investigations using asymmetric mixed-mode bending specimens. In such specimens, the crack propagated along paths outside the symmetry plane, and therefore mode partitioning could not be performed in the standardized way as for symmetric specimens. Existing techniques for the characterization of the mixed-mode fracture behavior of adhesively-bonded joints, the partitioning of the fracture mode components, and the modeling of the fiber bridging that affects the total fracture energy are presented in this chapter.

Simulating the effect of fiber bridging and asymmetry on the fracture behavior of adhesively-bonded composite joints

The fracture behavior of adhesively-bonded pultruded double cantilever beam specimens is studied in this chapter. The crack propagates along paths away from the symmetry plane and is accompanied by fiber bridging. Finite element models are developed to quantify the effects of asymmetry and fiber bridging on the fracture energy. The virtual crack closure technique can be used for calculation of the fracture components at the crack tip and an exponential traction–separation cohesive law can be applied to simulate the fiber-bridging zone. The cohesive zone model developed in this chapter can be used for simulating progressive crack propagation in other joint configurations composed of the same adherends and adhesive.