Progressive failure analysis of composite cuff connections for pultruded fiber reinforced plastic box sections

Abstract

In this thesis, cuff connections for pultruded fiber reinforced plastic box sections are investigated by Finite Element Method. Prediction of fiber and matrix damage of models was based on Hashina??s failure criterion and delamination was investigated using the equation proposed by Ochoa and Engblom. By employing the degradation factors after the elements met failure criterion, nonlinear failure analysis was carried out to study the connection performance after damage. The models were first verified by comparing three models with referenced experimental results. It was found that the stiffness, strength and failure modes agreed very well with the referenced results. Finite element models were then generated to investigate the performance of other cuff connections and possible optimization for designing this type of connection. The parameters investigated include cuff wall thickness, dimensions of rounded fillets at cuff corners, cuff-beam length and adhesive thickness above and below PFRP box beam flange. It was found that cuff connection with larger wall thickness and/or rounded fillets improved the stiffness and strength of the connection. For models with strong cuff, de-bonding might lead to connection failure if the cuff-beam length was less than half of beam depth. The analysis results showed that adhesive thickness has marginal effect on the connection strength and stiffness.