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Fig. 9. Density of the AE events versus amplitude in the stress ranges (I, II and III) for FFRE composite (unaged and after 38 days ageing at 20 °C and 40 °C): (a) synthesis according to the ageing and (b) synthesis according to the stress ranges (I, II and III).

Figure 9 Density of the AE events versus amplitude in the stress ranges (I, II and III) for FFRE composite (unaged and after 38 days ageing at 20 °C and 40 °C): (a) synthesis according to the ageing and (b) synthesis according to the stress ranges (I, II and III).

Related Figures (10)

Fig. 1. Evolution of water uptake of FFRE composite after 90% RH ageing at 20 °( and 40°C. Fig. 1 shows the percentage of water absorbed for the samples after 90% RH ageing at 20 °C and 40°C, as a function of square root of ageing time divided by thickness. The solid curves show the the- oretical water uptake behaviour predicted from Fick’s second law of diffusion. The curves were calculated by using Eq. (4) for the lin- ear part and by using Eq. (5) for the second part. Saturation weight gains and diffusion coefficients are shown in Table 1. Both curves in Fig. 1 are found to follow Fickian type behaviour. It can be seen that temperature has an influence on moisture uptake of FFRE composite. Results shown in Fig. 1 reveal that the increase of the
Fig. 1. Evolution of water uptake of FFRE composite after 90% RH ageing at 20 °( and 40°C. Fig. 1 shows the percentage of water absorbed for the samples after 90% RH ageing at 20 °C and 40°C, as a function of square root of ageing time divided by thickness. The solid curves show the the- oretical water uptake behaviour predicted from Fick’s second law of diffusion. The curves were calculated by using Eq. (4) for the lin- ear part and by using Eq. (5) for the second part. Saturation weight gains and diffusion coefficients are shown in Table 1. Both curves in Fig. 1 are found to follow Fickian type behaviour. It can be seen that temperature has an influence on moisture uptake of FFRE composite. Results shown in Fig. 1 reveal that the increase of the
Fig. 3. Stress-strain response under tension loading for FFRE composite. Diffusion kinetic parameters. Table 2
Fig. 3. Stress-strain response under tension loading for FFRE composite. Diffusion kinetic parameters. Table 2
Values of equilibrium water uptake M,, and diffusion coefficient D. Fig. 2. Diffusion case fitting plots for FFRE composite at 20 °C and 40 °C. Table 1
Values of equilibrium water uptake M,, and diffusion coefficient D. Fig. 2. Diffusion case fitting plots for FFRE composite at 20 °C and 40 °C. Table 1
Maximal strain according to the time of ageing. Table 3
Maximal strain according to the time of ageing. Table 3
Fig. 4. Evolution of mechanical properties according to ageing time: Young’s modulus (a), and tensile strength (b).
Fig. 4. Evolution of mechanical properties according to ageing time: Young’s modulus (a), and tensile strength (b).
Fig. 5. Comparison of distribution of AE signals during tensile tests on FFRE composite (unaged and after 38 days of ageing) according to: amplitudes (a) and duratio signal (b).
Fig. 5. Comparison of distribution of AE signals during tensile tests on FFRE composite (unaged and after 38 days of ageing) according to: amplitudes (a) and duratio signal (b).
Fig. 6. Pictures of FFRE composite polished with specific lubricant (a) and with water (b), perpendicularly to the fibre axis.
Fig. 6. Pictures of FFRE composite polished with specific lubricant (a) and with water (b), perpendicularly to the fibre axis.
Fig. 7. Schematic representation of individual flax-fibre (a) main walls (b) initial orientation of microfibrils inside the S2 wall (c) orientation of microfibrils inside the S2 wall (with hygrothermal ageing) under tensile loading.
Fig. 7. Schematic representation of individual flax-fibre (a) main walls (b) initial orientation of microfibrils inside the S2 wall (c) orientation of microfibrils inside the S2 wall (with hygrothermal ageing) under tensile loading.
Fig. 8. SEM pictures taken from the fracture surfaces of FFRE composite: unaged (a-b), after 38 days of ageing at 20 °C and 90% RH (c) and after 38 days of ageing at 40 °C and 90% RH (d).
Fig. 8. SEM pictures taken from the fracture surfaces of FFRE composite: unaged (a-b), after 38 days of ageing at 20 °C and 90% RH (c) and after 38 days of ageing at 40 °C and 90% RH (d).
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