Statistical analysis of dimensional deviations and geometrical imperfections of pultruded GFRP open-section profiles

This study presents a statistical analysis of the geometrical variability measured in glass-fibre reinforced polymer (GFRP) open-section profiles from the process-induced deformations of pultrusion. This study offers insights into the variability of geometric parameters, critical for reliability assessments and for establishing partial factors for design. Prior research has often provided limited data on geometric measurements, with some studies employing questionable measurement methodologies. Leveraging accurate measurement technology, specifically a 3D coordinate measurement machine (CMM), the authors analysed twenty-one pultruded-GFRP (pGFRP) specimens, each measuring 1.5 m in length. These specimens represented seven distinct open cross-section geometries, spanning four typological shapes: I-, W-, C-, and L-sections. The methodology employed in this analysis involved the evaluation of two groups of variables: dimensional deviation and geometrical imperfection. The measured data is compared against manufacturing tolerances outlined in the current standards, including EN 13706–2, ASTM D3917, and GB/T 31539. The statistical analysis includes correlation matrix analysis, box plots, mode shape assessment, probability distribution function fitting, and goodness-of-fit evaluation. It is shown that Lognormal and Normal distributions effectively capture most of the variability observed in geometrical variables within pGFRP open-section profiles. Moreover, this study underscores discrepancies between existing manufacturing standards and our findings, pointing out to a need for their revision. Furthermore, it emphasizes the importance of establishing standardized procedures for quantifying geometric imperfections in pGFRP composites to enhance computational simulations and design procedures.