# A Sensitivity Analysis of the Damage Behavior of a Leading-Edge Subject to Bird Strike
## 1 Introduction  
Damages resulting from bird strikes can seriously compromise the structural integrity of the aircraft. Therefore, large research studies can be found in the literature, focused on reducing human and air losses, developing new materials and design configurations of the parts most exposed to bird strike risks and developing bird control programs at airports to reduce the frequency of bird strikes. Therefore, stringent requirements have been selected and continuously updated by aviation safety agencies like the Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA) [1] in the certification procedures of each aircraft component. Recently, the EASA [2] proposed certification protocols providing guidance on certification aspects to be considered when using modeling and simulation techniques based on finite computational methods, and it clarifies that general compliance with structural certification specifications can be demonstrated by testing or by analyses supported by tests in case of similarities. Over the past decade, authors have studied several examples of aircraft structure topics and associated major certification specifications in the form of computational finite method techniques. Attention was paid to the certification process of some structural components of airplanes, for which a vast campaign of experimental tests was useful for the validation of the numerical models representingthe structure and the impactor [3; 4; 5]. Among the extensive literature research, different works focusing on the bird impact behavior on the windshield [6; 7], wing flap [8] and leading edge [9; 10; 11]; these results made it possible to implement different material configurations, such as composite incorporated with shape memory alloy material [12; 13] or laminated material [14; 15], by evaluating the behavior of the dynamic impact even at full scale [16], and in an attempt to improve components crashworthiness with respect to mass saving [17]. Moreover, several investigations were carried out by varying the characteristics of the volatile mass by using different projectile formulations, as smooth particle hydrodynamic (SPH) [18; 19] and Lagrangian [20; 21; 22]. In recent years, many authors have analyzed and simulated the bird-strike event against a specific part of the aircraft. [PERSON] et al. [23] provided a validated simulation methodology to support bird-strike certification of the Boeing 787 Dreamliner carbon fiber epoxy composite mobile trailing edge. [PERSON] et al. (2004) [24] performed a numerical simulation of the impact of birds against the turbofan engine intake and discussed the advantages and disadvantages of using different bird modeling techniques. [PERSON] et al. [25] investigated the impact of birds against the aluminum foam sandwich panel using the arbitrary Lagrangian-Eulerian (ALE) approach. To go beyond the state of the art, this work identifies the best compromise between weight and crashworthy design among the configurations capable of withstanding the bird strike phenomenon. This objective is achieved by using the ModeFrontier [26] code in conjunction with the FE Abaqus Explicit code [27] with a dedicated Python routine. Experimental tests have been used to verify and validate the model in order to guarantee the credibility and the acceptance of the results. Indeed, defining and creating test configurations and test articles, as well as actually running tests, can be expensive and time-consuming. Furthermore, even the test can be cumbersome; in particular, the difficulties of bird-strike tests can be related to their repeatability, to the management, and also to all the design cases to be examined and that can be manufactured. For these and other reasons, the use of numerical analyses is becoming increasingly widespread, particularly in the form of modeling and simulation techniques. This trend is further supported by the increase in computational capabilities, as well as the increased accuracy and ease of use of commercially available numerical tools.