Title: Overcoming Attenuation: Single-Sided NDI Characterization of Distal Bondlines in Engineered Foam Core Sandwich Structures

Authors: Nathaniel Blackman

DOI:

Abstract: Foam-cored sandwich composites are increasingly adopted in aerospace and industrial applications. While these composite structures present many benefits, their use is often limited by the challenges associated with quality assurance. Specifically, verifying the integrity of the opposing (distal) skin-to-core bondline remains a significant hurdle for Non-Destructive Inspection (NDI) when access is restricted to a single side. High signal attenuation inherent in porous core materials typically obscures defects at depth, forcing operators to rely on complex, dual-sided through-transmission techniques that are often impractical for large, integrated structures. This presentation introduces a novel inspection methodology utilizing LoneStar NDE Innovations’ Orion collaborative robot inspection system. The Orion system combines ultrasonic resonance inspection methodologies with contour following capabilities and rapid no-code, noCAD part teaching to create a rapidly deployable automated inspection system. By creating Cscans using ultrasonic resonance, we will demonstrate Orion’s ability to penetrate through up to 19 mm thick ROHACELL® foam and clearly resolve disbond defects in both near and far-side bondlines from a single-sided inspection. This work, performed in partnership with Evonik, will highlight the use cases, advantages, and inspection methodologies of a popular engineering grade foam on the market, ROHACELL. We will outline the material’s structural advantages, including superior specific stiffness, durability, heat resistance, and isotropic properties which make it an ideal candidate for next-generation composite applications. By correlating flaws with subtle changes in the resonance response, an inspection technique will be shown that can identify all and discriminate between flaws in the near-side laminate skin as well as the near-side and far-side bondlines of the sandwich structure.

References: 1. 2. 3. 4. 5. 6. 7. 8. 9. Kausar, A.; Ahmad, I.; Rakha, S.A.; Eisa, M.H.; Diallo, A. State-Of-The-Art of Sandwich Composite Structures: Manufacturing—to—High Performance Applications. Journal of Composites Science 2023, 7, 102, doi:10.3390/jcs7030102. Foam Core Impresses in Aircraft Study. Reinforced Plastics 2014, 58, 31–33, doi:10.1016/S0034-3617(14)70248-6. ROHACELL® Foam For Space Applications 90245 - SAMPE Available online: https://www.nasampe.org/store/viewproduct.aspx?id=4362234 (accessed on 13 February 2026). Hsu, D.K. Nondestructive Evaluation of Sandwich Structures: A Review of Some Inspection Techniques. Jnl of Sandwich Structures & Materials 2009, 11, 275–291, doi:10.1177/1099636209105377. Nsengiyumva, W.; Zhong, S.; Lin, J.; Zhang, Q.; Zhong, J.; Huang, Y. Advances, Limitations and Prospects of Nondestructive Testing and Evaluation of Thick Composites and Sandwich Structures: A State-of-the-Art Review. Composite Structures 2021, 256, 112951, doi:10.1016/j.compstruct.2020.112951. Watkins, S.; Bittner, J. Resonance Bond Testing: Theory and Application. Materials Evaluation 2021, doi:10.32548/2021.me-04225. Culbertson, L. The Resonating Realities of Single Sided Ultrasonic Inspection of Metal Bonded Assemblies. Presented at the Airlines for America (A4A) Conference, San Francisco, 2014. Cawley, P. The Impedance Method of Non-Destructive Inspection. NDT International 1984, 17, 59–65, doi:10.1016/0308-9126(84)90045-2. Crane, R.L.; Dillingham, G. Composite Bond Inspection. J Mater Sci 2008, 43, 6682–6694, doi:10.1007/s10853-008-2690-2. 10. ISO 10218-1:2025 Available online: https://www.iso.org/standard/73933.html (accessed on 13 February 2026). 11. ANSI/RIA R15.06-2012 - Industrial Robots and Robot Systems - Safety Requirements (CONTAINS CORRIGENDUM) Available online: https://webstore.ansi.org/standards/ria/ansiriar15062012?ad_acct=0000&gad_source=1&gad _campaignid=33646344&gbraid=0AAAAAD_gXFVoTVw4LQiGrSdZboNcb3fti&gclid=Cj wKCAiAtLvMBhB_EiwA1u6_Ptaq-V93SNqIS34N5PdWT0reWZZ7ddyq8T4m7SWNIrAR75F1kOKYRoC4LsQAvD_BwE (accessed on 13 February 2026). 12. ROHACELL® HERO - Evonik Industries Available online: https://performancefoams.evonik.com/en/products-and-solutions/ROHACELL/ROHACELL-hero-170036.html (accessed on 13 February 2026).

Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 306

Pages: 15

Price: $30.00