Finite element prediction of resin pocket geometry around embedded optical fiber sensors in prepreg composites

Abstract

This work presents a finite element technique allowing for the accurate prediction of resin pocket geometries surrounding optical fiber sensors in UD prepreg composites. The F.E. implementation solely relies on material models and element formulations readily available in all commercial F.E. codes, rather than requiring specialized user developed element and material formulations. In addition, only a minimal amount of straight-forward experimental characterization is required to determine the necessary material parameters in the model. The F.E. results are validated with microscopic images of several layups with embedded optical fiber samples of different diameters. Very good correspondence is found between F.E. results and microscopic cross-sections, showing the usefulness and applicability of the method to random lay-ups and optical fiber dimensions.

Prediction of resin pocket geometry around rigid fiber inclusion in composite laminate by hot-pressing of prepregs

“…It is well known that the bending stiffness of uncured laminate is much lower because of the sliding between adjacent fibers, which was also pointed out by Lammens et al. 26 Dickey et al. extended the method of Case and Carman to account for the resin pocket geometry in a nonsymmetric laminate about the optical fiber, 27 and they developed an analytical tool to generate the resin pocket geometry along a curve optical fiber path.…”

The study of internal structure of woven glass and carbon fiber reinforced composite materials with embedded fiber-optic sensors

“…Among other factors are the mechanical properties of the composite material, the layer's thickness, the number and stacking sequence of the layers, the size of the optical fiber, curing pressure and etc. In the study [9] an approach to determine the shape of a resin pocket, based on numerical finite element modeling of the pressing process in a plane-strain formulation of the theory of elasticity, is considered. Verification of the obtained numerical results with real cross-sectional images of polymer composite material (PCM) samples with embedded optical fiber showed the reliability of this method for determining the shape of the resin pocket.…”

Mode I interlaminar fracture toughness of carbon‐epoxy coupons with embedded ceramic sensors

“…[4][5][6][7][8][9]11] Nonetheless, the designers still view the sensor as an implanted flaw which could be the initiation site for delamination growth, having a higher chance to cause deterioration of the properties of the parent material. [12,[14][15][16] These perturbations are a big unknown as they could have an influence on the mechanical properties and crack initiation of the parent structure due to the sensor's presence. [14] In all of them, the sensor creates geometric and material discontinuities inside the composite structure.…”

“…Because the sensor embedding is conceived in the structure itself, it causes small perturbations on the sensor's neighborhood such as resin pockets or plies misalignments . These perturbations are a big unknown as they could have an influence on the mechanical properties and crack initiation of the parent structure due to the sensor's presence.…”