Experimental investigation and uncertainty modelling of mechanical properties of a pultruded GFRP material

This paper presents a robust short-term investigation into the variability of relevant mechanical properties of a typical pultruded glass fibre-reinforced polymer (GFRP) material, manufactured by Fiberline Composites (Denmark), constituted by seven layers of E-glass fibers embedded in a polyester resin. This extensive material characterization experimental program involved testing the pultruded GFRP material in different directions and test configurations, according to standardized procedures, namely (i) longitudinal and transverse tension, (ii) longitudinal and transverse compression, (iii) in-plane shear in the xy and yx planes, (iv) interlaminar shear in the xz plane, and (v) pin-bearing in the longitudinal and transverse directions – x , y and z denote the longitudinal (or pultrusion), transverse and through-thickness directions, respectively. A total of 1053 mechanical characterization tests were performed. The paper begins with a detailed description of all the testing procedures, followed by an in-depth discussion of the results. Inferential statistical analyses and goodness-of-fitness tests were then carried out to determine the most suitable probabilistic models for each of the 17 experimentally determined mechanical properties, including their correlations. With a few exceptions, the Lognormal distribution consistently provided the best fit for most material properties. While the majority of these material properties exhibited low-to-moderate variability (coefficient of variation – CoV<10%), some displayed moderate variability (10%<CoV≤20%), and a few showed higher variability (CoV>20%). Lastly, the paper concludes with key findings, highlighting the importance of the results of this investigation towards the safe design of pultruded GFRP structures (profiles and connections).