PSI - Issue 71

Deepak Kumar et al. / Procedia Structural Integrity 71 (2025) 380–387

382

3. Low velocity impact analysis of unidirectional hybrid (flax/sisal/carbon) composite The material properties taken for carbon-epoxy (T700CG/M21 epoxy) lamina are referred from Zhou et al. (2020). The unidirectional pre-peg has the following mechanical properties as mentioned in Table 1 .

Table 1: T700CG/M21 epoxy mechanical properties.

Carbon/epoxy composite lamina properties

Density

1600 kg/m 3

E 1 = 130000 MPa; E 2 = E 3 = 7700 MPa G 12 = G 13 = 4800 MPa; G 23 = 3800 MPa 12 = 13 = 0.33; 23 = 0.35 X T = 2080 MPa; Y T = Z T = 60 MPa X C = 1250 MPa; Y C = Z C = 140 MPa S 12 = S 23 = S 13 = 110 MPa G ft = 133000 N/m; G fc = 40000 N/m G mt =600 N/m; G mc =2100 N/m

Stiffness properties

Strength properties

Fracture energy

Interface properties

Elastic modulus Strength properties Fracture energy Relevant coefficient η

E n = E s = E t = 5000 MPa/mm

N = S = T = 30MPa n = 600 N/m; G c G c

s = 2100 N/m

1.45

Artificial damping coefficient Critical mode energy release rate

0.000001

G 1C = G 2C = 280 J/m

2 ; G

3C = 790 J/m 2

The impactor mechanical properties are taken from ANSYS ® material library as mentioned in Table 2. The material properties taken for sisal-epoxy lamina as referred from Mahesh et al. (2021) are mentioned in Table 3. The material properties taken for flax-epoxy lamina as referred from Hadj-Djilani et al. (2024) are mentioned in Table 4.

Table 2: Impactor properties.

Stainless Steel

Density

7750 kg/m 3 193000 MPa

Young’s modulus Poisson’s ratio Yield strength

0.31

For the purpose of hybridization

of studying the effect

210 MPa

on the impact properties of composite laminates, six laminate configurations cases are considered in the present work i.e., a) CCCC laminate configuration in which all the plies in the stacking belongs to carbon-epoxy (T700/M21) b) CFFC laminate configuration in which all the flax-epoxy plies are sandwiched in between carbon-epoxy plies c) CSSC laminate configuration i.e., sisal-epoxy plies are sandwiched in between carbon-epoxy plies

Table 3: Sisal-epoxy mechanical properties.

Sisal-epoxy composite lamina properties

Density

1310 kg/m 3

Stiffness properties

E 1 =456 MPa; E 2 = E 3 =180 MPa G 12 = G 13 =G 23 =208 MPa 12 = 0.27; 23 = 13 =0.04 X T =102 MPa; Y T = Z T =1.3 MPa X C =11.5 MPa; Y C = Z C =20.1 MPa S 12 = S 23 =7 MPa; S 13 =7 MPa Max normal traction=10 6 MPa

Strength properties

Interface properties

d) CFSC laminate configuration has both flax-epoxy and sisal-epoxy plies sandwiched between carbon-epoxy plies e) FFFF laminate configuration in which all the plies in the stacking sequence belongs to flax-epoxy f) SSSS laminate configuration in which all the plies in the stacking sequence belongs to sisal-epoxy The stacking sequence taken for all cases is described in details in Table 5.