PSI - Issue 71

M Mohan Kumar et al. / Procedia Structural Integrity 71 (2025) 372–379

379

7. Conclusions The structural behavior of composite panels under static tensile loading was investigated through both numerical and experimental analysis, considering undamaged, damaged, and scarf-repaired configurations. Finite Element Analysis (FEA) was carried out prior to experimental testing to assess the effect of damage and the effectiveness of the repair strategy. The introduction of a central circular hole led to a significant reduction in tensile strength, with the damaged panel exhibiting more than a 62% decrease in load-bearing capacity compared to the undamaged panel. This reduction is attributed to the stress concentration generated around the hole. In contrast, the scarf-repaired panel showed a notable recovery, regaining approximately 50% of the strength lost due to damage. This result underscores the potential of scarf repairs in partially restoring structural performance. A strong correlation was observed between the experimental and numerical results for all panel types, with discrepancies limited to within 6%, thereby validating the reliability of the finite element model. Furthermore, the repaired panel exhibited lower strain values than the damaged configuration, indicating enhanced stiffness and improved load transfer due to the presence of the bonded patch. Overall, the findings confirm that scarf repair is a viable method for restoring stiffness and partial strength in damaged composite structures, and the FEA model offers an accurate predictive tool for assessing such repairs. Acknowledgements The authors express their gratitude to the director of CSIR-National Aerospace Laboratories and the Head of the Structural Integrity Division for their guidance and support during course of the work. References Adkins, D.W. and R.B. Pipes.1989. Tensile Behavior of Bonded Scarf Joints between Composite Adherends. In Proceedings of the Fourth Japan-U.S. Conference on Composite Materials. Washington, D.C. USA. Ahn, S.H. and G.S. Springer 2000. Repair of composite laminates. Federal Aviation Administration, DOT/FAA-00/46. Andrew J. Gunnion, Israel Herszberg. 2006. Parametric study of scarf joints in composite structures. Composite Structures 75: 364 – 376. Association, S.O.A.C.M. SACMA Recommended Test Method (SRM 2R-94) for Compression after impact Properties of oriented fiber-resin composites. 1994. Baker, A.A., R.J. Chester, and G.R. Hugo. Scarf repairs to graphite/epoxy aircraft components. National Conference Publication - Institution of Engineers, Australia. Baker, A.A., R.J. Chester, G.R. Hugo, and T.C. Radtke 1995. Scarf repairs to graphite/epoxy components. AGARD, Composite Repair of Military Aircraft Structures 12. Chester, R.J., A.A. Baker, G.R. Hugo, and T.C. Radtke 1999. Scarf repairs to highly strained graphite/epoxy structure. International Journal of Adhesion and Adhesives 2-3: 161. Chun H. Wang and Andrew J. Gunnion 2009. Optimum shapes of scarf repairs. Composites: Part A 40: 1407 – 1418. Goland, M. and E. Reissner 1944, Stresses in Cemented Joints. Journal of Applied Mechanics. Harman, A 2004. Testing of thick adherend bonded scarf joint 2D test coupons. CRC-ACS TM. Hart Smith, L.J 1973. Adhesive-bonded scarf and stepped-lap joints. McDonnell-Douglas Corp, Long Beach, Calif. Myhre, S.H. and C.E. Beck.1978. Repair concepts for advanced composite structures. 1978: Structures, Structural Dynamics and Materials Conference, 19th Bethesda, Md; United States; 3-5 Apr. 1978. Pipes, R.B. and D.W. Adkins. Strength and mechanics of bonded scarf joints for repair of composite materials [Final Report, Jun. 1981 - May 1982]. Soutis, C. and F.Z. Hu. Repair Design of Composites and Efficiency of Scarf Patch Repairs. In The 11 th International Conference on Composite Materials. 1997. Melbourne, Australia: Australian Composite Structures Society, Woodhead Pty. Ltd.