Issue 53

A. Desai et alii, Frattura ed Integrità Strutturale, 53 (2020) 426-433; DOI: 10.3221/IGF-ESIS.53.33 431 Fig. 5 shows K IC vs. s/d for various fiber-oriented laminates. Critical Stress Intensity factors are increasing from pure Mode-II to pure Mode-I. Fig. 6 shows K IIC vs. s/d for various fiber-oriented laminates. Critical Stress Intensity factors are decreasing from pure Mode-II to pure Mode-I. Also, we can observe (0/90)° fiber oriented laminate is dominant compared to other fiber oriented laminate. Critical stress intensity factor is considered as fracture toughness. The failure under Mixed mode loading i.e. variation of K IIC vs. K IC is depicted in Fig. 7. This nature of variation of K IIC vs. K IC is in good agreement with the results shown by our earlier experimental work under Mixed mode loading [10]. Fracture toughness value of (0/90)° fiber oriented laminates are highest among other fiber oriented laminates. Also, (0/90)° fiber orientation fabrication is simple compared to (0/45)° fiber orientation. Hence (0/90)° fiber oriented laminates can be preferred for industrial purpose. Fig. 8 shows K eff vs . s/d for various fiber-oriented laminates. This figure indicates that, the effective stress intensity factor in Mode-I is more than that of Mode-II which indicates specimen fails earlier in Mode-I compared to Mode-II and Mixed modes.. Also, nature of variation of K eff vs . s/d is similar to earlier researchers [2]. Fig. 9 shows fracture behavior of laminates at different loading positions from s/d=0 to 1. From Fig. 9 we can see that, for s/d=0, fracture takes in pure Mode-II. For s/d=1, fracture takes place in pure Mode-I. For s/d=0.2, 0.4, 0.6 and 0.8 fracture takes place in Mixed mode. As we have conducted experimentation on specimen using crack perpendicular to fiber direction, the nature of failure will be translaminar. After the experiment crack tip is examined through optical microscope having 100X magnification which reveals fiber breakage as is shown in Fig. 10. Figure 5: K IC vs. s/d Figure 6: K IIC vs . s/d fiber Figure 7: K IIC vs. K IC Figure 8: K eff vs. s/d