Fragmentation model for the tensile response of unidirectional composites based on the critical number of fiber breaks and the correction of the fiber-matrix interfacial strength.

Abstract

A fragmentation model based on global load sharing (GLS) theory is developed to obtain stress-strain curves that describe the mechanical behavior of unidirectional composites. The model is named + * because it is based on the Critical Number of Breaks model (CNB) and on the correction of the fiber matrix interfacial strength, *. Model allows both obtaining the ultimate tensile strength of CFRP and GFRP composites, and correcting the vs curve to match its peak point with the predicted strength, which is more accurate than the one obtained by previous GLS-based models. Our model is used to classify the mechanical response of the material according to the energetic contributions of two phenomena up to the failure: intact fibers (IF) and fragmentation (FM). Additionally, the influence of fiber content, , on the tensile strength, , failure strain, , and total strain energy, , is analyzed by means of novel mechanical-performance maps obtained by the model. The maps show a dissimilar behavior of , and with between GFRP and CFRP composites. The low influence of on the percent energetic contributions of IF and FM zones, as well as the larger energetic contribution of the FM zone, are common conclusions that can be addressed for both kinds of composites.

Fragmentation model for tensile behavior of intermingled hybrid composites and optimal mixing ratio

“…For the last fiber mixing ratio, α=0.75 (Figure 6h), ultimate tensile strength of CNB+τ* model is in the range of the other two models (FEM and FPM), but the ultimate strain is overpredicted. The CNB+τ* model was previously validated in [36] with experimental results for non-hybrid composites. In total, 25 experimental works were considered, obtaining an average relative difference of 5.01%.…”

“…Given the advantage of GLS-based models to provide fast results, a model to accurately predict the ultimate tensile strength of unidirectional composites within a GLS framework, named CNB+τ* model, was previously developed [35], [36]. According to that model, the failure of the composite occurs when a critical density of fiber breaks, depending entirely on the constituent properties, is reached; when such happens, the fiber breaks interaction becomes significant to create 'avalanches events' of broken fibers that bring about the failure.…”

“…• (1 − ), respectively, the critical number of breaks per unit length �Λ C �, ultimate tensile strength � + * � and corrected fiber-matrix interfacial strength ( * ) for each sub-composite are computed using the CNB+τ* model [36]. Thereupon, the final mechanical response of the hybrid composite can be obtained for any value of α as it was described in section 3.3.…”

“…Other approaches have focused on the local fiber arrangement, where the proportion, as well as the thickness of the constituents, plays an important role in obtaining a pseudo-ductile response [9], [11], [12], [32]- [34]. In previous works [35], [36], we developed a Global Load Sharing (GLS)-based model, named CNB+τ* model, to obtain the stress-strain curves of glass and carbon unidirectional composites considering the critical number of fiber breaks and the correction of the fiber-matrix interfacial strength. The accuracy of CNB+τ* model was assessed by comparing the ultimate tensile strengths with the experimental ones reported in the literature.…”

Structure Property Investigation of Glass-Carbon Prepreg Waste-Polymer Hybrid Composites Degradation in Water Condition

“…However, GF-PP had the lowest GF content in comparison to CPW-PP and GF-CPW-PP. Previous studies reported that [30][31][32][33] composite failure mechanisms may be represented as follows: when there is no load disruption by the reinforcement break under mechanical testing, the load is uniformly distributed among the fibres next to the break fibre resulting in a degree of concentrated stress developing on those fibres and damaging the surrounding matrix. Therefore, the presence of intense moisture increased vulnerability and decreased the tensile strength of the composites.…”