Kevlar Radomes Beat Glass Fiber in Simulated Hailstone Strikes on Airliner Nose Cones

When a commercial airliner punches through a towering cumulonimbus cloud, few parts of the airframe sit closer to danger than the radome, the rounded nose cone that shelters the weather radar from the elements. A new computational study from researchers at the Manipal Institute of Technology in India suggests that the material chosen for this forward-facing shield matters far more than engineers might assume, and that swapping conventional glass fiber composites for Kevlar-based laminates could deliver both better impact protection and a meaningful weight saving at the same time.

The research, published as an open-access paper in the International Journal of Aeronautical and Space Sciences, simulated a 50.8 millimeter hailstone, the classic two-inch benchmark of aviation hail threat models, slamming into a radome modeled on the Airbus A320neo at a combined velocity of roughly 240 meters per second, the speed of a typical cruise condition. The team, led by Anand Pai with co-authors including P. K. Sowmya, Khushhali Chaudhary, Suhas Yeshwant Nayak, Chandrakant R. Kini and B. Satish Shenoy, compared two industry-standard fiber-reinforced polymer systems: glass fiber-reinforced polymer, or GFRP, and Kevlar, or p-aramid, fiber-reinforced polymer, known as KFRP. The verdict was unambiguous. The KFRP radome limited peak deformation to 8.1 millimeters, an 18 percent reduction compared with the 9.88 millimeters suffered by the GFRP variant, while weighing about 19 percent less.

The stakes are far from academic. The researchers compiled a survey of documented hailstone strikes on commercial aircraft over the past decade, and the record shows a rising frequency of encounters, a trend the authors attribute to the growing incidence of severe convective weather and the continued expansion of global air traffic. Hailstones routinely strike the nose cone, fuselage, wing skins, leading edges, control surfaces, engine nacelles and fan blades. The radome is particularly exposed because of its forward-facing geometry, and the minimum skin thickness requirements imposed to protect it carry a real weight penalty, one that matters acutely for smaller jets where every kilogram affects performance and fuel burn.

Modeling a hailstone is deceptively hard. Natural hail is polycrystalline ice, a layered, anisotropic material riddled with air and water pockets, and its mechanical behavior swings dramatically with strain rate. At the high strain rates of 100 to 300 per second typical of these impacts, ice transitions from ductile to brittle failure, yet high-speed imaging shows it retains residual strength through fragmentation and axial splitting even after damage initiates. Its compressive strength and hardness can climb by more than 300 percent as temperature falls from minus 15 to minus 50 degrees Celsius. The team represented the projectile using Smoothed Particle Hydrodynamics, a mesh-free method that sidesteps the severe mesh distortion that cripples traditional Lagrangian finite element approaches during extreme deformation. The hailstone was discretized into 67,731 particles of one millimeter each, governed by a bilinear isotropic constitutive model that captures the critical moment when the ice’s deviatoric stress vanishes at the failure threshold and the projectile begins to behave like a fluid.

The radome itself was built with equal care. The 7.5 millimeter skin was assembled from thirty discrete plies of 0.25 millimeters each in a symmetric [0/90]15 stacking sequence of 2 by 2 twill weave fabric. Rather than plugging in generic material cards, the researchers derived the effective orthotropic properties through a multi-scale homogenization workflow: representative volume elements of the unidirectional yarn architecture and the bidirectional woven architecture were simulated in ANSYS Material Designer, using manufacturer data for Kevlar 2200 aramid fibers with a Young’s modulus of 108 gigapascals and EC11 204 E-glass fibers at 72.4 gigapascals, both embedded in an epoxy matrix. The resulting laminate definitions were then exported into ANSYS Explicit Dynamics, where the coupled SPH-finite element framework ran the impact scenarios over a 100 microsecond window.

The simulation reproduced a two-stage impact response well known from experimental literature on flat composite panels: a rapid loading stage in which stress and deformation climb to a peak, followed by a rebound stage as the projectile fragments and the stress decays. On the curved radome geometry, the two materials diverged after about 40 microseconds. Up to that point their deformation histories were nearly indistinguishable, but the GFRP shell then deformed more steeply toward its larger final value, while the KFRP laminate held a more stable late-stage profile. Contact stress told a complementary story. The KFRP radome reached a higher peak stress of roughly 1581 megapascals at about 60 microseconds, versus about 890 megapascals at 70 microseconds for GFRP, indicating a stiffer, more localized response that accelerates hailstone fragmentation and spreads the debris tangentially along the radome’s curvature, a phenomenon the authors call geometric shedding.

Energy accounting reinforced the picture. Both simulations began with an identical projectile kinetic energy of 1925 joules, and total energy was conserved throughout, with hourglass energy held below 2 percent of peak internal energy, satisfying standard explicit dynamics stability criteria. But the KFRP radome accumulated more internal energy and showed a sharper decay of the projectile’s kinetic energy, signatures of enhanced momentum dissipation through multi-axial matrix shearing and plastic work. In other words, the aramid architecture does not merely deflect the blow; it absorbs and dissipates the impact energy more effectively across the convex surface of the nose cone.

Perhaps the most technically interesting contribution is the ply-by-ply failure analysis. Because global mechanical metrics poorly capture the directional nature of composite damage, the team implemented a sequential explicit-to-implicit mapping: deformation states extracted at 40, 60, 80 and 100 microseconds from the explicit solver were transferred into a static implicit environment, where the anisotropic Tsai-Wu failure criterion yielded an Inverse Reserve Factor for individual plies. An IRF at or above 1.0 signals the onset of material degradation. The results exposed a fundamental difference in damage character. In the GFRP radome, elevated failure indices spread diffusely, with the rear ply reaching IRF values up to 3.30 across wide, unconfined contours, a pattern that raises the risk of widespread micro-cracking, shear failure and interlaminar delamination. The KFRP radome, by contrast, confined its most severe indices, which climbed as high as 11.79, to a narrow zone at the impact apex, while the mid-plane plies stayed comparatively protected. Damage containment, not merely damage resistance, emerged as the Kevlar laminate’s decisive advantage, preserving the load-bearing capacity of the surrounding shell and the radar instruments behind it.

To bridge the gap between idealized single impacts and operational reality, the researchers also ran a cluster scenario of five concurrent 50.8 millimeter hailstones spaced 60 millimeters apart, extending the simulation to 5 milliseconds to capture staggered strikes and shockwave interactions. The result was a wider concave indentation with surface cratering across the central radome region, a damage envelope that closely resembles photographic evidence of real hail damage on an operational Interjet A320 nose cone. That qualitative agreement, the authors argue, validates the framework’s ability to capture the momentum transfer required to produce macroscopic cratering. The team is candid about limitations: the bilinear ice model omits thermal effects and microstructural heterogeneity, and future work will add stochastic multi-impact scenarios and cohesive zone modeling to probe the interplay between intralaminar softening and delamination. Still, the message for aircraft designers is striking. A radome built from Kevlar rather than glass fiber could shed roughly 19 percent of its mass, about 114 kilograms in the modeled geometry, while deforming less, absorbing more energy and keeping damage tightly contained where it matters least to the aircraft’s survival.

Subject of Research: Computational simulation of hailstone impact response of composite aircraft radomes

Article Title: Dynamic Impact Response of Composite Aircraft Radomes Subjected to Hailstone Impact: A Computational Study

Article References: Pai, A., Sowmya, P. K., Chaudhary, K., Nayak, S. Y., Kini, C. R., & Satish Shenoy, B. (2026). Dynamic Impact Response of Composite Aircraft Radomes Subjected to Hailstone Impact: A Computational Study. International Journal of Aeronautical and Space Sciences. https://doi.org/10.1007/s42405-026-01308-2

Image Credits: AI Generated

DOI: 10.1007/s42405-026-01308-2

Keywords: aircraft radome, hailstone impact, Kevlar, GFRP, composite laminates, SPH, finite element analysis, Tsai-Wu failure criterion, aviation safety, explicit dynamics, impact damage, A320neo