Structural Assessment and Repair Feasibility of Surface Defects in Composite Sandwich Panels

Abstract:

Composite sandwich panels are extensively used in aerospace, automotive, and construction applications due to their exceptional strength-to-weight ratio and structural efficiency. However, local surface deviations, such as waviness and dents, often develop during manufacturing and operation, potentially leading to adhesion failures and delamination between the composite skin and the core. This study aims to establish acceptable defect size limits that can be corrected through technological pressing, ensuring structural integrity of composite material while minimizing the negative impact on load-bearing capacity of sandwich panels. An analytical approach was adopted to assess the stress behavior of composite skins with waviness and elliptical dent defects. The analysis was based on beam and plate theory, incorporating the effects of flexural rigidity, material anisotropy, and applied technological pressure. The Hill strength criterion was applied to define permissible defect limits, considering variations in structural criticality levels. The study determined the maximum allowable sizes for waviness and dents in composite sandwich panels, factoring in the responsibility level of the panel, expressed as the maximum stress intensity coefficient. The results show that the acceptable defect size decreases with increasing structural criticality. It was also found that forced compression of dents induces pre-stress zones within the composite skin, potentially altering its stress distribution and reducing its long-term load-bearing capacity. The proposed methodology provides a quantitative framework for evaluating acceptable defect limits, supporting manufacturing quality control and repair optimization. The results offer practical insights for enhancing the reliability and durability of composite structures, ensuring that local surface deviations remain within permissible limits without compromising structural performance.

• Periodical: Materials Science Forum (Volume 1162)
• Pages: 9-18
• DOI: https://doi.org/10.4028/p-rC1Zus
• Online since: October 2025
• Authors: Andrii Kondratiev*, Tetyana Nabokina, Oleksii Kabus, Oleksandr Ivanenko
• Keywords: Delamination, Dents, Load-Bearing Capacity, Repair, Stress Intensity, Surface Irregularities, Waviness

References

[1] P. Resende Oliveira, M. May, T. Hallak Panzera, S. Hiermaier, Bio-based/green sandwich structures: A review. Thin-Walled Struct.. 177 (2022) 109426.

DOI: 10.1016/j.tws.2022.109426

[2] G.L. Vatulia, A.O. Lovska, Ye.S. Krasnokutskyi, Research into the transverse loading of the container with sandwich-panel walls when transported by rail. IOP Conf. Ser.: Earth Environ. Sci.. 1254 (2023) 012140.

DOI: 10.1088/1755-1315/1254/1/012140

[3] A. Kondratiev, V. Píštěk, V. Gajdachuk, M. Kharchenko, T. Nabokina, P. Kučera, O. Kučera, Effect of ply orientation on the mechanical performance of carbon fibre honeycomb cores. Polymers. 15(11) (2023) 2503.

DOI: 10.3390/polym15112503

[4] Sagin, O. Kuropyatnyk, A. Sagin, I. Tkachenko, O. Fomin, V. Píštěk, P. Kučera, Ensuring the environmental friendliness of drillships during their operation in special ecological regions of Northern Europe. J. Mar. Sci. Eng.. 10 (2022) 1331.

DOI: 10.3390/jmse10091331

[5] R. Hsissou, R. Seghiri, Z. Benzekri, M. Hilali, M. Rafik, A. Elharfi, Polymer composite materials: A comprehensive review. Compos. Struct.. 262 (2021) 113640.

DOI: 10.1016/j.compstruct.2021.113640

[6] Y. Li, D. Zhang, Local stress distributions in fiber-reinforced composites with consideration of thermal stresses during the curing process. Mech. Compos. Mater.. 57(5) (2021) 675–686.

DOI: 10.1007/s11029-021-09987-6

[7] A. Kondratiev, V. Píštěk, O. Vambol, P. Kučera, Effect of heating conditions during moulding on residual stress–strain behaviour of a composite panel. Polymers. 14(9) (2022) 1660.

DOI: 10.3390/polym14091660

[8] V.S. Balakrishnan, H. Seidlitz, Potential repair techniques for automotive composites: A review, Compos. Part B: Eng.. 145 (2018) 28–38.

DOI: 10.1016/j.compositesb.2018.03.016

[9] Z.G. Wang, Z.D. Li, W. Zhou, D. Hui, On the influence of structural defects for honeycomb structure. Compos. Part B: Eng.. 142 (2018) 183–192.

[10] W. Zhou, X.-L. Ji, S. Yang, J. Liu, L.-H. Ma, Review on the performance improvements and non-destructive testing of patches repaired composites. Compos. Struct.. 263 (2021) 113659.

DOI: 10.1016/j.compstruct.2021.113659

[11] S. Kurennov, N. Smetankina, K. Barakhov, Axisymmetric stress state of adhesive joint of a circular patch with a plate weakened by a circular cut-out. Period. Polytech. Mech. Eng.. 67(1) (2023) 12–18.

DOI: 10.3311/ppme.18801

[12] S. Olhan, B. Antil, B.K. Behera, Repair technologies for structural polymeric composites: An automotive perspective. Compos. Struct.. 352 (2025) 118711.

DOI: 10.1016/j.compstruct.2024.118711

[13] E. Archer, A. McIlhagger, Repair of damaged aerospace composite structures, in: P.E. Irving, C. Soutis (Eds.), Polymer Composites in the Aerospace Industry, 2nd ed., Woodhead Publishing, Sawston, UK, 2020, рр. 441–459.

DOI: 10.1016/b978-0-08-102679-3.00015-0

[14] A. Köllner, Predicting buckling-driven delamination propagation in composite laminates: An analytical modelling approach, Compos. Struct.. 266 (2021) 113776.

DOI: 10.1016/j.compstruct.2021.113776

[15] N. Shabanijafroudi, R. Ganesan, A new methodology for buckling, postbuckling and delamination growth behavior of composite laminates with delamination. Compos. Struct.. 268 (2021) 113951.

DOI: 10.1016/j.compstruct.2021.113951

[16] D. Zebrine, E. Wadhwani, S. Nutt, Surface porosity development in tool-side facesheets of honeycomb core sandwich structures during co-cure. Adv. Manuf.-Polym. Compos. Sci.. 8 (2022) 43–55.

DOI: 10.1080/20550340.2022.2056313

[17] J.T. Siivola, S. Minakuchi, T. Mizutani, K. Kitamoto, N. Takeda, Monitoring of dimple formation in honeycomb sandwich structures using distributed fiber optic sensors. J. Sandwich Struct. Mater.. 23 (2021) 3645–3668.

DOI: 10.1177/1099636220935821

[18] S. Ručevskis, T. Rogala, A. Katunin, Monitoring of damage in composite structures using an optimized sensor network: A data-driven experimental approach. Sensors. 23(4) (2023) 2290.

DOI: 10.3390/s23042290

[19] B. Wu, M. Destrade, Wrinkling of soft magneto-active plates. Int. J. Solids Struct.. 208–209 (2021) 13–30.

DOI: 10.1016/j.ijsolstr.2020.10.020

[20] V.V. Rizov, A. Shipsha, D. Zenkert, Indentation study of foam core sandwich composite panels. Compos. Struct.. 69(1) (2005) 95–102.

DOI: 10.1016/j.compstruct.2004.05.013

[21] C.T. James, P.R. Cunningham, A. Watson, Experimental and numerical investigation of the effect of asymmetry on the residual strength of a composite sandwich panel. J. Sandwich Struct. Mater.. 17(4) (2015) 417–445.

DOI: 10.1177/1099636215577348

[22] V. Slyvyns'kyy, V. Gajdachuk, V. Kirichenko, A. Kondratiev Basic parameters' optimization concept for composite nose fairings of launchers. 62nd International Astronautical Congress, IAC 2011. Cape Town, 3–7 October 2011. Red Hook NY: Curran. 9 (2012) 5701–5710.

[23] L.M. Gavva, V.V. Firsanov, Analytical review of account methods and experimental approaches to stress-strain state investigation of structurally-anisotropic aircraft panels made from composite materials. IOP Conf. Ser. Mater. Sci. Eng.. 927 (2020) 012067.

DOI: 10.1088/1757-899x/927/1/012067

[24] Q. Guo, W. Yao, W. Li, N. Gupta, Constitutive models for the structural analysis of composite materials for the finite element analysis: A review of recent practices. Compos. Struct.. 260 (2020) 113267.

DOI: 10.1016/j.compstruct.2020.113267

[25] P. Gontarovskyi, N. Smetankina, N. Garmash, I. Melezhyk, Numerical analysis of stress-strain state of fuel tanks of launch vehicles in 3D formulation, in: M. Nechyporuk, V. Pavlikov, D. Kritskiy (Eds.), Integrated Computer Technologies in Mechanical Engineering – 2020. Springer. Cham. 188 (2021) 609–619.

DOI: 10.1007/978-3-030-66717-7_52

[26] V. Miroshnikov, O. Savin, V. Sobol, V. Nikichanov, Solving the problem of elasticity for a layer with N cylindrical embedded supports. Computation. 11(9) (2023) 172.

DOI: 10.3390/computation11090172

[27] K. Maiorova, I. Vorobiov, M. Boiko, V. Suponina, O. Komisarov, Implementation of reengineering technology to ensure the predefined geometric accuracy of a light aircraft keel. East.-Eur. J. Enterp. Technol.. 6(1) (114) (2021) 6–12.

DOI: 10.15587/1729-4061.2021.246414

[28] J.A. Mills, A.W. Hamilton, D.I. Gillespie, I. Andonovic, C. Michie, K. Burnham, C. Tachtatzis, Identifying defects in aerospace composite sandwich panels using high-definition distributed optical fibre sensors. Sensors. 20(23) (2020) 6746.

DOI: 10.3390/s20236746

[29] D.I. Gillespie, A.W. Hamilton, R.C. Atkinson, X. Bellekens, C. Michie, I. Andonovic, C. Tachtatzis, Defect detection in aerospace sandwich composite panels using conductive thermography and contact sensors. Sensors. 20(22) (2020) 6689.

DOI: 10.3390/s20226689

[30] D. Tkachenko, Y. Tsegelnyk, S. Myntiuk, V. Myntiuk, Spectral methods application in problems of the thin-walled structures deformation. J. Appl. Comput. Mech.. 8(2) (2022) 641–654.

[31] A. Szafraniec, S. Halko, O. Miroshnyk, R. Figura, A. Zharkov, O. Vershkov, Magnetic field parameters mathematical modelling of windelectric heater. Przegląd Elektrotechniczny. 97(8) (2021) 36–41.

DOI: 10.15199/48.2021.08.07

[32] V. Pasternak, A. Ruban, M. Surianinov, Y. Otrosh, A. Romin, Software modeling environment for solving problems of structurally inhomogeneous materials. Mater. Sci. Forum. 1068 (2022) 215–222.

DOI: 10.4028/p-h1c2rp

[33] V. Golovanevskiy, A. Kondratiev, Elastic properties of steel-cord rubber conveyor belt, Exp. Techn.. 45(2) (2021) 217–226.

DOI: 10.1007/s40799-021-00439-3

[34] A. Kondratiev, L. Smovziuk, M. Shevtsova, A. Tsaritsynskyi, T. Nabokina, Study of reduction of strength of composite plates with delamination, in: Advances in Mechanical and Power Engineering, CAMPE 2021, Lecture Notes in Mechanical Engineering, Springer. Cham. 2023, p.159–168.

DOI: 10.1007/978-3-031-18487-1_16

[35] V.V. Vasiliev, E.V. Morozov, Laminated composite beams and columns, in: Advanced Mechanics of Composite Materials, 3rd ed., Elsevier, Amsterdam. The Netherlands. 2013, p.435–486.

DOI: 10.1016/b978-0-08-098231-1.00008-x

[36] V.V. Vasiliev, E.V. Morozov, Failure criteria and strength of laminates, in: Advanced Mechanics of Composite Materials, 3rd ed., Elsevier, Amsterdam. The Netherlands. 2013, p.299–352.

DOI: 10.1016/b978-0-08-098231-1.00006-6

[37] V.V. Vasiliev, E.V. Morozov, Laminated composite plates, in: Advanced Mechanics of Composite Materials, 3rd ed., Elsevier, Amsterdam. The Netherlands. 2013, p.487–583.

DOI: 10.1016/b978-0-08-098231-1.00009-1

[38] A. Tiwary, R. Kumar, J.S. Chohan, A review on characteristics of composite and advanced materials used for aerospace applications. Mater. Today Proc.. 51 (1) (2022) 865–870.

DOI: 10.1016/j.matpr.2021.06.276

[39] A.V. Haidachuk, B. Wang, S.A. Bychkov, et al., Development of an integrated criterion for the rational choice of polymeric composite materials. Mater. Sci.. 55 (2020) 899–907.

DOI: 10.1007/s11003-020-00385-2