Collapse of channel section composite profile subjected to bending Part II: Failure analysis

The paper presents the failure analysis of thin-walled channel section composite beams made of GFRP laminate. Six arrangements of layers were analysed. Two scenarios were investigated in the performed tests: pure bending and bending with torsion. In order to characterise the process of failure, the following techniques were used: ultrasonic non-destructive testing, computed microtomography and scanning electron microscopy. The conducted failure analysis based on macro and microscopic tests allow to identify the location, geometry and the character of the failure areas. Furthermore, occurrence of characteristic forms and mechanisms of failure was revealed. Based on the conducted analyses it was concluded that the failure of reinforcing fibres, as a result of compressive and shearing stresses, is a major/dominant form of failure for most of the studied configurations. Detailed analysis of the failure areas allowed to determine the influence of orientation and position of particular layers on the character of damage of the tested beams. The type and distribution of the observed forms of failure indicate that the character of degradation of particular layers with different orientations remains heterogeneous to a large extent.