Strength prediction of a joint composed of a pultruded FRP tube bonded to an FRP lamella

Adhesively bonded connections involving pultruded FRP typically fail in a brittle manner, making their analysis a case study for the application of statistical size effects. For brittle materials, in which failure is often caused by a single critical defect, statistically based size effects on strength are adequately explained by probabilistic theories such as the Weibull strength theory. A previously implemented probabilistic dimensioning method for adhesively bonded balanced joints is extended to a complex joint involving a tube and a lamella, both made of pultruded FRP. Instead of the previously used 2d approach the extension requires a 3d formulation. The entire joint is idealized as being constituted by n elements; its survival depends on the simultaneous survival of all elements. By the means of a 3d FEA, failure triggering stress components in all n elements were determined; a probability of failure is associated to each element using the corresponding combination stresses combined into an appropriate failure criterion, hence defining a theoretical joint strength.