Title: Characterization of Composite Materials Using Atomic Force Microscopy and Finite Element Simulation for Industrial Application

Authors: William Bruner, Maximillian Westby, Masoud Yekani Fard

DOI:

Abstract: Scanning probe microscopy (SPM) is increasingly used to characterize the nanoscale mechanical behavior of polymer composites for aerospace and advanced manufacturing applications. By indenting the surface with a probe and measuring cantilever deflection, SPM provides stiffness and deformation data that can be used to infer local material properties. However, in heterogeneous composite systems, the measured stiffness is not a direct material property but rather reflects a convolution of multiple physical mechanisms. While several of these effects have been studied individually, their combined influence on the SPM signal has not been systematically quantified. In this work, a finite element framework is used to measure the effects of confinement, strain hardening, and damage on SPM stiffness measurements. The slope of the unloading segment of the force–displacement response is used as the numerical analog of the SPM stiffness signal. The results show that confinement strongly increases the apparent stiffness when a reinforcing element is present, strain hardening alters the unloading response in a non-intuitive manner, and damage reduces the measured stiffness. Together, these findings demonstrate that multiple interacting mechanisms govern SPM measurements in composite systems and must be accounted for to obtain reliable nano and micro-scale mechanical data.

References: [1] Binnig, Gerd, Quate, Calvin Forrest, and Gerber, Christoph. “Atomic Force Microscope.” Physical Review Letters 56 (1986): 930-933. https://doi.org/10.1103/PhysRevLett.56.930. [2] García, R. J., Proksch, R., Kocun, M., Polívka, L., and Bennewitz, R. “Nanomechanical mapping of soft materials with the atomic force microscope: methods, theory and applications.” Chemical Society Reviews, 49(2020): 5850–5884. DOI: 10.1039/D0CS00318B. [3] Payam, A.F. and Passian A., “Imaging beyond the surface region: probing hidden materials via atomic force microscopy”, Sci Rev Adv. 9 (26)(2023):1-18. DOI: 10.1126/sciadv.adg8292 [4] Wang, D., and Russell, T. P. “Advances in atomic force microscopy for probing polymer structure and properties.” Macromolecules, 51(1)(2018): 3–24. DOI: 10.1021/acs.macromol.7b01459 [5] Zhou, X., Fu, J., Li, Y., Li, F. “Nanomechanical mapping of glass fiber reinforced polymer composites using atomic force acoustic microscopy”, Journal of Applied Polymer Science 131 (2014). https://doi.org/10.1002/app.39800 [6] Shen, Z., Dong, R., Li, J., Su, Y., and Long, X. “Determination of gradient residual stress for elastoplastic materials by nanoindentation,” Journal of Manufacturing Processes 109 (2024): 359–366.https://doi.org/10.1016/j.jmapro.2023.10.030 [7] C. Chu, H. Ge, N. Gu, K. Zhang, C. Jin, “Interfacial microstructure and mechanical properties of carbon fiber composite modified with carbon dots,” Composites Science and Technology 184 (2019). https://doi.org/10.1016/j.compscitech.2019.107856 [8] Yekani Fard, Masoud, and Pensky, Alex. “Stochastic multiscale multimode interlaminar fracture toughness of buckypaper nanocomposites.” International Journal of Mechanical Sciences 237 (2023). https://doi.org/10.1016/j.ijmecsci.2022.107798 [9] Yekani Fard, Masoud and Raji, Brian. “Statistical analysis of peak force atomic force microscopy data for the interphase thickness and modulus in carbon fiber-reinforced epoxy resin composites exposed to different heat and humidity levels.” Journal of Aerospace Engineering 34(5) (2021). https://doi.org/10.1061/(ASCE)AS.1943-5525.0001311 [10] Yekani Fard, Masoud, and Norkus, Tyler. “Introducing a nano-scale surface morphology parameter affecting fracture properties of CNT nanocomposites.” Composites Communications 48 (2024). https://doi.org/10.1016/j.coco.2024.101931 [11] Yekani Fard, Masoud and Raji, Brian. “Effects of long-term exposure to heat and humidity on submicron scale properties in composite materials.” Proceedings of AIAA Science and Technology Forum and Exposition. Virtual, Online, January 11-15 & 19-21, 2021. https://doi.org/10.2514/6.2021-0065 [12] Yekani Fard, M., Raji, B., & Pankretz, H. “Correlation of nanoscale interface debonding and multimode fracture in polymer carbon composites with long-term hygrothermal effects.” Mechanics of Materials 150 (2020). DOI: 10.1016/j.mechmat.2020.103601. [13] Wang, Guorui, Dai, Zhaohe, Liu Luqi, Hu, Hai, Dai, Qing, and Zhang, Zhong. “Tuning the Interfacial Mechanical Behaviors of Monolayer Graphene/PMMA Nanocomposites.” ACS Applied Materials & Interfaces 8 (2016): 22554-22562. DOI: 10.1021/acsami.6b03069. [14] Yekani Fard, Masoud. “Carbon nanotube network and interphase in buckypaper nanocomposites using atomic force microscopy.” International Journal of Mechanical Sciences 212 (2021). https://doi.org/10.1016/j.ijmecsci.2021.106811 [15] Yekani Fard, Masoud. “Interphase of Single and Double CNT Networks with Surrounding Polymer in Atomic Force Microscopy.” Proceedings of AIAA Science and Technology Forum and Exposition. Virtual, Online, January 23-27, 2023. https://arc.aiaa.org/doi/abs/10.2514/6.2023-2231. [16] Yekani Fard, M., Norkus, T., and Westby, M. “Weibull Analysis of Multiscale Properties of Nanoparticle Bundles in Nanomembrane.” Proceedings of AIAA SciTech Forum 2025. DOI: 10.2514/6.2025-0137. [17] Zhang, Min, Li, Yang, Kolluru, Pavan V., and Brinson, L. Catherine. “Determination of Mechanical Properties of Polymer Interphase Using Combined Atomic Force Microscope (AFM) Experiments and Finite Element Simulations.” Macromolecules 51 (20) (2018): 8229-8240. https://doi.org/10.1021/acs.macromol.8b01427. [18] Song, J., Kahraman, R., Collinson, D. W., Xia, W., Brinson, L. C., and Keten, S. “Temperature effects on the nanoindentation characterization of stiffness gradients in confined polymers.” Soft Matter 15(3): 359–370. DOI: 10.1039/C8SM01539B [19] Saito, Io, Sheridan, Richard J., Zauscher, Stefan, and Brinson, L. Catherine. “Pushing AFM to the Boundaries: Interphase Mechanical Property Measurements near a Rigid Body.” Macromolecules 58 (2) (2024): 980-988. https://doi.org/10.1021/acs.macromol.4c01993. [20] Collinson, D.W., Eaton, M.D, Shull, K.R., and Brinson, L.C. “Deconvolution of Stress Interaction Effects from Atomic Force Spectroscopy Data across Polymer-Particle Interfaces.” Macromolecules 52 (22) (2019): 8940-8955 DOI: 10.1021/acs.macromol.9b01378 [21] Ohashi, T., Sato, T., Nakajima, T., Junkong, P., & Ikeda, Y. “Necessity of two-dimensional visualization of validity in the nanomechanical mapping of atomic force microscopy for sulphur cross-linked rubber.” RSC Advances 8 (2018): 32930–32941. DOI: 10.1039/C8RA06669H. [22] Hasan, M. M., Johnson, C. L., & Dunn, A. C., “Soft Contact Mechanics with GradientStiffness Surfaces,” Langmuir, 38(31)(2022): 9454–9465. DOI: 10.1021/acs.langmuir.2c00296. [23] Wang, G., Najafi, F., Ho, K., Hamidinejad, M., Cui, T., Walker, G. C.; Singh, C. V., Filleter, T. “Mechanical size effect of freestanding nanoconfined polymer films.” Macromolecules, 55(2022): 1248–1259. https://doi.org/10.1021/acs.macromol.1c02270 [24] Zak, S., Trost, C. O. W., Kreiml, P., & Cordill, M. J., “Accurate measurement of thin film mechanical properties using nanoindentation,” Journal of Materials Research 37 (7)(2022): 1373–1387. https://doi.org/10.1557/s43578-022-00541-1. [25] Westby, M., Raji, B., Wilbur, J. D., & Yekani Fard, M.. “Deconvolution of atomic force microscopy data from the effects of destructive indentation in heterogeneous polymer composite systems.” Proceedings of AIAA Scitech Forum and Exposition, (2025) DOI: 10.2514/6.2025-0764. [26] Church, J. J., Raji, B., Wilbur, J. D., & Yekani Fard, M. “Effect of embedment depth of hard inclusions on force–displacement curves through AFM and FEA. Proceedings of AIAA Scitech Forum and Exposition. January 6-10, 2025. DOI: 10.2514/6.2025-2642. [27] Norkus, T., and Yekani Fard, M. “Modeling of nanoscale characteristics of carbon nanotube nanocomposites through experimental and statistical methods.” Proceedings of ASME International Mechanical Engineering Congress and Exposition. January 23, 2025. https://doi.org/10.1115/IMECE2024-144779 [28] Westby, M., Yekani Fard, M., Norkus, T., & Boutin, W. “Deconvolution of Atomic Force Microscopy Data From the Effects of Destructive Indentation in Soft Material Systems.” Proceedings of ASME International Mechanical Engineering Congress and Exposition (IMECE 2024). DOI: 10.1115/IMECE2024-144462. [29] Spitzig, W. A. and Richmond, W. F. “Effect of hydrostatic pressure on the deformation behavior of polyethylene and polycarbonate in tension and compression.” Polymer Engineering & Science 19 (16) (1979): 1238-1244. https://doi.org/10.1002/pen.760191602. [30] Westby, Maximillian, Bruner, William and Yekani Fard, Masoud. "Interfacial Debonding of Embedded Particles in Nanocomposite Systems Using Atomic Force Microscopy and Finite Element," Proceedings of AIAA SCITECH 2026 Forum. January 2026. DOI: 10.2514/6.2026-0575 [31] Doerner, M.F., Nix, W.D. “A method for interpreting the data from depth-sensing indentation instruments”. Journal of Materials Research 1: 601–609 (1986). https://doi.org/10.1557/JMR.1986.0601

Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 58

Pages: 13

Price: $26.00