Strain rate effect on composites with epoxy matrix filled by cork powder

Silva, Marco Aurélio Pinto; Santos, P.; Sousa, Nuno; Reis, P.N.B.

doi:10.1002/mdp2.47

Cited by 8 publications

(6 citation statements)

References 52 publications

(67 reference statements)

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“…Decreases of around 18% and 40.4% can be found for maximum loads and stiffness, respectively, while the displacement at maximum load increases by about 25.5%. These values are in line with others reported in the literature [31,[48][49][50], where the insertion of cork into composites decreases the bending strength and modulus, but the bending strain increases. In fact, cork deforms because the cell walls bend and buckle and can undergo large strain deformation.…”

Section: Resultssupporting

confidence: 93%

Impact Response of Composite Sandwich Cylindrical Shells

2021

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Nowadays, due to the complexity and design of many advanced structures, cylindrical shells are starting to have numerous applications. Therefore, the main goal of this work is to study the effect of thickness and the benefits of a carbon composite sandwich cylindrical shell incorporating a cork core, compared to a conventional carbon composite cylindrical shell, in terms of the static and impact performances. For this purpose, static and impact tests were carried out with the samples freely supported on curved edges, while straight edges were bi-supported. A significant effect of the thickness on static properties and impact performance was observed. Compared to thinner shells, the failure load on the static tests increased by 237.9% and stiffness by 217.2% for thicker shells, while the restored energy obtained from the impact tests abruptly increased due to the collapse that occurred for the thinner ones. Regarding the sandwich shells, the incorporation of a cork core proved to be beneficial because it promoted an increase in the restored energy of around 44.8% relative to the conventional composite shell. Finally, when a carbon skin is replaced by a Kevlar one (hybridization effect), an improvement in the restored energy of about 20.8% was found. Therefore, it is possible to conclude that numerous industrial applications can benefit from cylindrical sandwiches incorporating cork, and their hybridization with Kevlar fibres should be especially considered when they are subject to impact loads. This optimized lay-up is suggested because Kevlar fibres fail through a series of small fibril failures, while carbon fibres exhibit a brittle collapse.

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Section: Resultssupporting

confidence: 93%

Impact Response of Composite Sandwich Cylindrical Shells

2021

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“…Finally, as suggested by the literature [55][56][57], a linear model can be fitted to the data according to Equations ( 6)-( 8), with which it is possible to obtain the sensitivity to strain rate through the slope of the curves [58]. It is possible to observe that the maximum bending stress increases for all laminates with an increase in strain rate, which is in line with the literature [49,53].…”

Section: Resultssupporting

confidence: 77%

Effect of Carbon Nanofibers on the Strain Rate and Interlaminar Shear Strength of Carbon/Epoxy Composites

2023

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The static bending properties, different strain rates and interlaminar shear strength (ILSS) of carbon-fiber-reinforced polymers (CFRP) with two epoxy resins nano-enhanced with carbon nanofibers (CNFs) are studied. The effect on ILSS behavior from aggressive environments, such as hydrochloric acid (HCl), sodium hydroxide (NaOH), water and temperature, are also analyzed. The laminates with Sicomin resin and 0.75 wt.% CNFs and with Ebalta resin with 0.5 wt.% CNFs show significant improvements in terms of bending stress and bending stiffness, up to 10%. The values of ILLS increase for higher values of strain rate, and in both resins, the nano-enhanced laminates with CNFs show better results to strain-rate sensitivity. A linear relationship between the logarithm of the strain rate was determined to predict the bending stress, bending stiffness, bending strain and ILSS for all laminates. The aggressive solutions significantly affect the ILSS, and their effects are strongly dependent on the concentration. Nevertheless, the alkaline solution promotes higher decreases in ILSS and the addition of CNFs is not beneficial. Regardless of the immersion in water or exposure to high temperatures a decrease in ILSS is observed, but, in this case, CNF content reduces the degradation of the laminates.

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“…Hence, the normalised stress-strain behaviours are similar to the cases under tensile loadings, but it could have non-linear response before fracture at higher strain rates (Figure 6). For instance, according to Silva et al [14], Kevlar composites with pure resin, the maximum bending stress increases from 188.1 MPa at 1.3 × 10 −1 s −1 to 243.3 MPa at 1.3 × 10 −1 s −1 , represents an increment around 29.3%. The stress-strain curve exhibit two region-a quasi-linear region and followed by a nonlinear region.…”

Section: Flexural Strain Ratementioning

confidence: 95%

“…The crack initiation and propagation in the tensile test were found e affected by the strain rate variation. Silva et al [14] found the cork powder re Most of the studies towards the effects of strain rates in the past have been focused on synthetic fibre polymer composites [12]. While the behaviour of NFPCs under various strain rates has only been investigated recently.…”

Section: Introductionmentioning

confidence: 99%

“…The crack initiation and propagation in the tensile test were found extremely affected by the strain rate variation. Silva et al [14] found the cork powder reinforced epoxy bending stress and strain are also sensitive under a wide range of strain rates. Furthermore, Xiang et al [15] found the hemp fibre reinforced epoxy is compressive strain rates sensitive.…”

Section: Introductionmentioning

confidence: 99%

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A Review on Mechanical Properties of Natural Fibre Reinforced Polymer Composites under Various Strain Rates

et al. 2021

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With the lightning speed of technological evolution, the demand for high performance yet sustainable natural fibres reinforced polymer composites (NFPCs) are rising. Especially a mechanically competent NFPCs under various loading conditions are growing day by day. However, the polymers mechanical properties are strain-rate dependent due to their viscoelastic nature. Especially for natural fibre reinforced polymer composites (NFPCs) which the involvement of filler has caused rather complex failure mechanisms under different strain rates. Moreover, some uneven micro-sized natural fibres such as bagasse, coir and wood were found often resulting in micro-cracks and voids formation in composites. This paper provides an overview of recent research on the mechanical properties of NFPCs under various loading conditions-different form (tensile, compression, bending) and different strain rates. The literature on characterisation techniques toward different strain rates, composite failure behaviours and current challenges are summarised which have led to the notion of future study trend. The strength of NFPCs is generally found grow proportionally with the strain rate up to a certain degree depending on the fibre-matrix stress-transfer efficiency. The failure modes such as embrittlement and fibre-matrix debonding were often encountered at higher strain rates. The natural filler properties, amount, sizes and polymer matrix types are found to be few key factors affecting the performances of composites under various strain rates whereby optimally adjust these factors could maximise the fibre-matrix stress-transfer efficiency and led to performance increases under various loading strain rates.

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Strain rate effect on composites with epoxy matrix filled by cork powder

Cited by 8 publications

References 52 publications

Impact Response of Composite Sandwich Cylindrical Shells

Impact Response of Composite Sandwich Cylindrical Shells

Effect of Carbon Nanofibers on the Strain Rate and Interlaminar Shear Strength of Carbon/Epoxy Composites

A Review on Mechanical Properties of Natural Fibre Reinforced Polymer Composites under Various Strain Rates

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