Evaluation of the stiffening mechanism based on micro-sized particle inclusions in laminated composites

Abstract

Rigid particles have been incorporated into laminated composites, especially to enhance their bending performance attributed to the stiffening of the matrix phase (i) and the increased interlaminar shear resistance (ii). In order to better evaluate the improvement mechanism provided by the particulate inclusions, this work investigates the incorporation of micro-sized silica on the top, bottom and both surfaces of glass fibre laminates, mitigating the interference of the interlocking effect. Three-point bending, and impact tests are performed to evaluate the hybrid glass fibre composites containing 5, 7.5 and 10 wt% of micro silica. In addition, the effect of the micro silica particles into epoxy polymers is verified under tensile, compressive and abrasion tests. A finite element model is developed to simulate the three-point bending test and to better assess the behaviour of the composite laminate. Although silica particles lead to increased compressive modulus of the epoxy polymers, their positive effect on glass fibre composites under flexural loads is more evident when placed on the bottom side of the laminates subjected to the maximum tensile stress. The incorporation of 7.5 wt% silica microparticles at the bottom surface of the laminates achieves higher flexural strength and lower impact resistance.

Assessment of damping and flexural behaviour of hybrid fibre-particulate composites

“…This behaviour can be addressed to the interlocking effect between particles and fibres. These findings confirm the results reported by Ribeiro Junior et al, 36 who obtained greater flexural strength of hybrid composites containing glass fibres and silica particles.…”

“…This comparison allows for the assessment of the model’s accuracy in capturing the behaviour of the hybrid composites under three-point bending. In the FE simulations, the elastic properties of glass and carbon plies (Table 3), as well as the damage properties (Table 4), are extracted from reputable sources such as Rahimian Koloor et al, 34 Ribeiro et al, 35 Ribeiro Junior et al, 36 while the values of fracture energies are obtained from the properties provided by Shi et al 37 By utilizing data from these sources, the model can effectively capture the mechanical response of the hybrid composites in the FE simulations.

Figure 5.Representative FE model for three-point bending analysis.

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Static, fatigue and impact behaviour of an autoclaved flax fibre reinforced composite for aerospace engineering

“…In addition, other plies under tension are closer to the neutral line, therefore reducing their stiffening effect on the overall bending modulus. A similar behaviour has been discussed by Junior et al [34] in a glass fibre composite with unbalanced beam stiffness due to the inclusion of rigid particles in the matrix phase. It is also worth of notice that the seventh ply located on the neutral line does not contribute to axial stresses through bending loads.…”

“…Table 5 shows the absolute and specific bending properties, as well as the number of plies aligned with the tensile loads located below the neutral line. The compressive loads located on the upper beam side are largely dominated by the properties of the matrix [34]. On the other hand, the presence of fibres aligned with the tensile loads on the lower beam side plays an important role in the bending behaviour of the laminates.…”