Analytical determination of the critical impact location for wing leading edge under birdstrike

Abstract The wing leading edge is one of the aircraft structures which are vulnerable to birdstrike. Therefore, Federal Aviation Regulation has clear requirements of anti-birdstrike performance for wing leading edge. However, the impact location is not specified in aviation regulation. The forefront of the wing leading edge is selected as a critical location for the birdstrike in most researches. But the rationality of the selection is not given. This paper proposes an analytical method for determining the critical location that causes the most severe damage under impact due to birdstrike. The analysis is based on the concept of effective impact, i.e. the component of the bird velocity perpendicular to the surface of wing leading edge. A birdstrike model is established using Pam-crash and used to validate the analytical prediction. The numerical model proves its effectiveness compared to the birdstrike test. The residual compressive strength of the spar when the birdstrike is at the critical impact location determined by the proposed method is 44.5% of that at the traditional impact location. Moreover, the critical penetrating velocity of the traditional impact location is not the lowest. In other words, the traditional impact location is not the weakest. Airworthiness verification experiment of birdstrike on wing structure should pay attention to this aspect.

摘要 机翼前缘是易遭受鸟撞的飞机结构之一。联邦航空条例（Federal Aviation Regulation）对机翼前缘的抗鸟撞性能提出了明确要求，但该航空条例并未明确规定鸟撞的具体冲击位置。现有多数研究均将机翼前缘最前端选为鸟撞关键位置，却未论证该选择的合理性。本文提出一种分析方法，用于确定鸟撞冲击下造成最严重损伤的关键位置。该分析基于有效冲击的概念，即鸟体速度垂直于机翼前缘表面的分量。本文采用Pam-crash建立鸟撞数值模型，以验证该分析预测结果；通过与鸟撞试验对比，验证了该数值模型的有效性。采用本文方法确定的关键冲击位置发生鸟撞时，翼梁的剩余抗压强度仅为传统冲击位置下的44.5%。此外，传统冲击位置的临界穿透速度并非最低，即传统冲击位置并非结构最薄弱处。飞机机翼结构鸟撞的适航验证试验应重视该问题。