## 1 Introduction  
The problem of damage repair of aviation weapon equipment on the battlefield has a long history. According to statistics, the number of battle-damaged aircraft is much greater than the number of battle-destroyed aircraft. Hence, rapid repair of battle-damaged aircraft can have a significant impact on the war situation by increasing operational intensity and ensuring sustained combat capability. Indeed, rapid repair of battle-damaged aircraft has attracted great attention as it is the most effective way to restore aircraft combat effectiveness [1]. The battle damage mode of aircraft is to study all possible conditions and combinations of threat sources causing battle damage. The battle damage simulation based on rapid repair is different from weapon effectiveness analysis, and the combat effectiveness and survivability analysis of aircraft. The purpose is to provide guidance on rapid repair techniques and to provide an aid for the analysis of rapid repair resource requirements, usually focusing on the analysis and research of battle damage of aircraft structures. The combat aircraft is the main target of all types of air defense weapons. Currently, carbon fiber composites have been widely applied in advanced fighters, especially in wing panels, vertical fins, fuselage skins, and rudders [2]. Carbon fiber laminates are the most important aerospace composite structure. The damage of a composite structure under the impact of combat fragments is different from that of a metallic structure, and its damage mechanism is more complex than that of metallic material. On one hand, the reinforced fiber limits the expansion of damage under the composite structure's own load, and on the other hand, the damage modes (such as the delamination of composite laminate structures) are not found in aerospace metal structures. The impact of the combat fragments on the composite laminate is a complex process of impact load evolution with time, structural deformation and damage extension. The impact damage of composite laminate is closely related to the laminate material's properties, lamination method, processing technology and the fragment's velocity, shape and quality. The damage mode and damage range of the laminate are different in different impact conditions. The possible damage mechanisms include fiber shear fracture, fiber tensile failure, matrix cracking, fiber matrix interface delamination and degumming. The damage mechanism and damage mode of a composite structure in a series of velocity ranges were investigated by numerical simulation and experiments. [PERSON] et al. conducted a hyper-speed impact test on CFRP/Al honeycomb composites and obtained the dynamic response of the structure with different thickness combinations [3]. [PERSON] et al. conducted a hyper-speed impact test and impact damage test analysis to solve the protection effect problem of a spatial debris soft protection structure composed of a soft protection screen made of multilayer soft composites [4]. [PERSON] et al. conducted a CFRP-Al/HC sandwich panel hyper-speed impact behavior analysis based on the finite element method. [PERSON] et al. conducted ballistic tests on braided T300 carbon fiber/epoxy composite flat-plate specimens and 3D X-ray computer tomography (CT) was used to image and visualize the resultant damage inside the samples. Modern aircraft are mostly multilayered thin-walled structures. Aircraft skin will often encounter penetrating damage under the action of high-velocity fragments, which has considerable penetration capabilities after penetrating the outer skin, and the secondary penetration of fragments will cause damage to the internal structure. The damage mode is closely related to the fragment's incident direction, incident velocity, and strike position [5]. The damage mode of aircraft composite/metal connecting structures under high-velocity impact has been little studied.