目的飞机在雨中高速飞行时，机体迎风面蒙皮涂层受到雨滴冲击作用而产生损伤，出现表面开裂、剥离等典型损伤，降低结构的安全性和功能性，因此需要对蒙皮涂层的雨蚀损伤机理进行深入研究。方法利用一级轻气炮搭建的单射流试验平台和水切割装置改装的多射流试验平台模拟雨滴冲击。针对以碳纤维T300编制材料为基体，表面涂有3种同等厚度的聚氨酯涂层材料，在不同试验条件下对材料进行雨蚀试验研究。结果在617m/s冲击速度条件下，以0°、15°、30°的冲击角度以及在15°冲击角度，430、490和555m/s的冲击速度下对三种涂层材料进行单射流试验；对三种涂层材料在350、370和420m/s的冲击速度下，进行1000次冲击的多喷射流试验。结果表明：随着冲击角度和速度的变化，三种涂层材料的损伤趋势是一致的；典型损伤形貌相同，即当水锤压力低于涂层材料的屈服强度极限时，损伤区域由环形损伤包围中央未损伤区域构成；当水锤压力超过材料的屈服强度极限时，水锤压力结合侧向射流会造成1～2倍于液滴直径的损伤区域。多射流与单射流的试验结果具有相似性。结论通过对比单射流与多射流试验下涂层材料的典型损伤形貌可知，材料的雨蚀损伤机理与...

As the main component of the aircraft leading edge, the radome is often the first to be hit by raindrops and cause structural damage when passing through a rain field. Rain resistant coating is usually applied to ensure the performance protection requirements. In order to clarify the rain erosion damage mechanism of radome coating and explore the influencing factors and mechanisms of coating material damage under different jet impact conditions, impact tests were conducted on three types of skin coating samples, and the damage mode was observed through electron microscopy characterization. The experimental results show that the typical morphology of rain erosion damage is annular surface peeling damage. The damage area and volume of the three coating samples increase with the continuous increase of raindrop impact velocity. The threshold velocity for initial damage to the coating is about 360 m/s; under the influence of the velocity component, the reduction in impact angle leads to a gradual reduction in the degree of damage to the sample. ABAQUS finite element simulation software was used to establish a constitutive model for coating rain erosion simulation and obtain the propagation law of stress waves during the impact process. The simulation results show that at the 75° impact angle, the jet impacts the surface of the specimen at different velocities, and as the impact velocity increases, the Mises equivalent stress on the surface shows an increasing trend, which is one of the main factors causing damage with increasing velocity. The effectiveness, rain erosion damage mode, and influencing mechanism of the model were verified based on the test results; the dynamic failure mechanism of the sample was further studied, and the stress propagation process at different impact angles was compared, revealing the influence mechanism and damage law of the impact angle on the high-speed raindrop impact of the material. © 2025 The Author(s)

The composite skin coating structure of the front edge of the supersonic aircraft body is deformed, cracked and even stripped due to the continuous impact of raindrops. The coating material used in this paper is based on carbon fiber T300 braided material, and its surface is coated with three different types of coatings. In order to reveal the rain erosion damage mechanism of the coating structure and establish the rain erosion damage criterion, the rain erosion test of three kinds of coatings was carried out by using the multi-jet rain erosion test device and the Hydro-impact test rig "Erosion-M". In the experiment, the coating material is simulated under two different rain erosion conditions: continuous droplet impact in the same location and large range droplet impact in real rain field. The damage behavior of the surface and cross section of the coating damage under the two rain erosion conditions was characterized and analyzed by digital microscope and scanning electron microscope (SEM), and the influence mechanism of impact conditions on the rain erosion damage of the coating material was discussed. The results show that the typical damage pattern of the samples after multi-jet impact is a funnelshaped damage pattern with severe damage in the middle and small damage all around. In the properties of coating materials, surface roughness has a significant effect on the latency of rain erosion damage, and mechanical parameters such as hardness and modulus mainly affect the expansion period of rain erosion damage. Among them, coating material 2 has better resistance to rain erosion. The damage degree increases with the increase of impact velocity and decreases with the decrease of impact Angle. The influence mechanism of roughness, modulus and hardness on rain erosion damage at different damage stages and under different impact conditions was revealed.

目的 研究飞机前缘蒙皮涂层材料高动态雨滴冲击损伤机理与影响因素，明晰雨蚀损伤的主要损伤模式与机制，为飞机抗雨蚀性能研究提供数据支持与理论基础。方法 基于一级10 mm口径轻气炮平台搭建单射流冲击试验装置，以T300碳纤维复合材料为基体，表面涂敷4种规格的聚氨酯涂层，研究了涂层力学性能与冲击速度、角度等因素对涂层雨蚀损伤程度的影响规律，建立了水射流冲击复合材料涂层结构的有限元模型，进一步揭示了涂层材料的雨蚀损伤行为与损伤机理。结果 高速射流冲击涂层时，仿真与试验结果基本吻合，验证了数值仿真模型方法的合理性；由于水锤压力的作用，涂层试样的雨蚀典型损伤形貌为环形损伤包围中央未损伤区；随着冲击速度的增加，应力水平逐渐增大，在接触瞬间会导致涂层内部产生裂纹分层，甚至表面分离翘起和剥离脱落。而随着冲击角度的增加，垂直方向上速度分量减小，在水平方向上侧向射流沿冲击投影正方向与反方向的速度存在明显差异，且仿真结果中路径应力水平也不相同，最终导致损伤形貌呈现明显的不对称性。结论 水射流的冲击速度和冲击角度是影响涂层雨蚀损伤程度的主要条件因素；水锤压力、应力波传播是涂层产生剥离与内部损伤的主要微观因素；水...

As a leading edge component, the aircraft fuselage skin can suffer severe damage to its surface coating structure due to the impact erosion of raindrops when the aircraft traverses through rainy conditions. With the increasing flight speed of aircraft, stricter requirements have been put forward for the rain erosion resistance of the fuselage coating. To clarify the mechanisms and affecting factors of rain erosion damage on the leading edge skin coating of aircraft and identify the damage criteria for rain erosion impacts, a single-jet impact test setup has been established based on a first-order light gas gun platform. With T300 carbon fiber composite material as the substrate, three different types and thicknesses of polyurethane coatings are applied to the surface. The effect of coating mechanical properties, impact velocity, angle, and other factors on the degree of rain erosion damage to the coatings is examined. A finite element model of the water jet impacting the composite coating structure during the impact process is developed based on Abaqus finite element simulation software to further reveal the rain erosion behavior and damage mechanisms of the coating material. The results indicate that when the high-speed jet impacts the coating, the simulated damage outcomes are generally consistent with the experimental results, showing uneven damage distribution at different impact angles, with deformation and delamination of the coating being the primary damage modes. This validates the rationality of the numerical simulation model method. The typical morphology of rain erosion damage is characterized by a circular damage area surrounding the central undamaged area. Under more severe impact conditions, the main damage modes are circular damage after peeling of topcoat and primer. It can be seen that cracks are generated due to the impact, and the edges of the cracks are lifted and broken, mainly in the erosion pit at the impact center, accompanied by the uplift of the surrounding surface layer, resulting in internal delamination damage. As impact conditions intensify, the surface coating cracks and peels off, resulting in circular detachment. The impact velocity and angle of the water jet are the primary factors affecting the degree of rain erosion damage to the coating. By combining simulation methods, the stress propagation patterns during the impact process are obtained. An increase in impact velocity directly leads to an increase in stress levels, causing surface coating detachment and internal crack delamination under stress during the impact instant, with the surface coating separating and lifting up. An increase in the impact angle reduces the velocity component in the vertical direction. In the horizontal direction, due to the presence of the impact angle, there is a significant difference in velocity between the lateral jet along the positive and negative directions of the impact projection, leading to differences in path stress levels in the simulation results and ultimately causing the damage morphology to exhibit a clear asymmetric distribution. Water hammer pressure and stress wave propagation are the main factors causing coating detachment and internal damage, while hydraulic infiltration and lateral jet effects are among the reasons for interlayer cracking in the composite skin coating structure. © 2025 Chongqing Wujiu Periodicals Press. All rights reserved.

Water-drop erosion may seriously damage the integrity of materials in aerospace systems. Various methods—theoretical, experimental, or numerical—may be used to investigate this phenomenon. By numerical modeling, data may be obtained regarding the stress and strain and other factors, without the need for experiments, which may be expensive and difficult to reproduce. Clear results are obtained. Numerical modeling of drop–surface interaction in equipment used to study water-drop erosion provides information regarding not only a single water drop but a flux of droplets. Ansys Workbench software is used for finite-element analysis. The utility of modeling the drop–surface interaction in determining the stress–strain state and the damage zone is considered, for a single water drop and a flux. The modeling results are compared with experimental data. © Allerton Press, Inc. 2025.

Abstract: Porosity is a problem in many technologies, such as additive manufacturing and the production of polymer, carbon, ceramic, carbon–carbon, and metal–polymer composites. It is a particular concern in the production of multilayer structures by reinforcement or layer-by-layer sintering and fusion. Regardless the technology and the materials employed, cavities of practically similar size, shape, and distribution are obtained, which may significantly affect the physicomechanical properties (elastic modulus, strength, etc.). The influence of the pores’ size, shape, and distribution is most often assessed by numerical modeling using the finite-element method. In the present work, the Digimat and Ansys Workbench software generally used to determine the effective properties of materials is considered. © Allerton Press, Inc. 2025.

Abstract: An axisymmetric initial and boundary value problem regarding the impact of a liquid drop on a solid surface at constant speed is considered, for different contact angles. Mathematically, Navier–Stokes equations are used to describe the motion of each phase (liquid, air). A method of numerical solution is described, and sample calculations are presented. © 2023, Allerton Press, Inc.