Low-velocity Impact Characterization of Glass,Carbon and Kevlar Composites Using Repeated Drop Tests

Abstract

Low-velocity (≅ 1.2-2.4 m/s) repeated drop weight impact tests were carried out on advanced composites (glass, carbon, kevlar in epoxy matrix - LY 556, HT 972) using an instrumented impact test machine (DYNATUP 8250). The incident energies ranged from 3.5 to 15 J (constant impactor mass 5.42 kg). Number of drops to failure (N_f) data were obtained for the above with simultaneous recording of the load-time and energy-time traces. The extent of impact damage for glass and kevlar composites was interpreted using final delamination area maps (tracings).

Results for all the three composites showed that with an increase in drop numbers, the peak load (P_L) steadily decreased while the total energy (E_t) increased, until failure. Also, as the incident energy (E_in) was varied in arithmetic progression, the number of drops to failure (N_f) varied in harmonic progression. Finally it was concluded that repeated drop tests with final delamination area maps assist in understanding the impact damage tolerance of polymer composites.

Keywords

impact damage tolerance arithmetic progression harmonic progression Ein — Nf plots repeated drops final delamination area maps

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References

1. Choi, Hyung Yon and Chang, Fu-Kuo (1992). A model for predicting damage in graphite/epoxy laminated composites resulting from low-velocity point impact , Journal of Composite Materials, 26(14): 2134-2169 .

2. Lin, H.J. and Lee, Y.J. (Nov 1990). Impact-induced fracture in laminated plates and shells , Journal of Composite Materials, 24: 1179-1199 .

3. Liu, Dahsin (July 1988). Impact-induced Delamination - A View of Bending Stiffness Mismatching , Journal of Composite Materials, 22: 674-692 .

4. Finn, Scott, R. and Springer, George, S. (1993). Delaminations in Composite Plates Under Transverse Static or Impact Loads - A Model , Composite Structures, 23: 177-190 .

5. Kumar, Prashant and Rai, Badri . (1991). Impact Damage on Single Interface GFRP Laminates - An Experimental Study , Composite Structures, 18: 1-10 .

6. Naik, N.K. and Chandrashekhar, Y. (1998). Damage in Laminated Composites due to Low Velocity Impact , Journal of Reinforced Plastics and Composites, 17(14): 1232-1263 .

7. Ying, Yan (1998). Analysis of Impact Threshold Energy for Carbon Fibre and Fabric Reinforced Composites , Journal of Reinforced Plastics and Composites, 17(12): 1056-1075 .

8. Rydin, R.W. , Bushman, M.B. and Karbhari, V.M. (Feb 1995). The Influence of Velocity in Low-velocity Impact Testing of Composites using the Drop Weight Impact Tower , Journal of Reinforced Plastics and Composites, 14: 113-127 .

9. Delfosse, Daniel and Poursartip, Anoush (1997). Energy Based Approach to Impact Damage in CFRP Laminates , Composites Part A, 28A(7-12): 647-655 .

10.

10. Cantwell, W.J. and Morton, J. (Sep 1991). The Impact Resistance of Composite Materials - A Review , Composites, 22(5): 341-362 .

11.

11. Richardson, M.O.W. and Wisheart, M.J. (1996). Review of Low-velocity Impact Properties of Composite Materials , Composites Part A, 27A: 1123-1131 .

12.

12. Hodgkinson, J.M. (2000). Mechanical Testing of Advanced Fibre Composites, p. 362, Woodhead Publishing Limited .

13.

13. Wyrick, D.A. and Adams, D.F. (Jan 1988). Damage Sustained by a Carbon/epoxy Composite Material Subjected to Repeated Impact , Composites, 19(1): 19-27 .

14.

14. Khan, Bijoysri, Rao, R.M.V.G.K. and Venkataraman, N. (Nov 1995). Low-velocity Impact Fatigue Studies on Glass Epoxy Composite Laminates with Varied Material and Test Parameters - Effect of Incident Energy and Fibre Volume Fraction , Journal of Reinforced Plastics and Composites, 14: 1150-1159 .