摘要:
为了研究翼身融合(Blended Wing Body, BWB)新构型民机的结构坠撞响应,以美国国家航空航天局提出的拉挤杆缝合一体化(Pultruded Rod Stitched Efficient Unitized Structure, PRSEUS)结构为基础,用临界机动载荷(2.5g过载和-1.0g过载)和客舱增压载荷(2倍客舱增压载荷)共3种典型载荷工况作为评估BWB结构强度、刚度的输入条件,建立了一款450座级的BWB民机结构模型。在垂向26 ft/s-30 ft/s的坠撞工况下,进行了数值模拟研究,重点分析了客舱空间保持情况、客舱地板的加速度响应以及主要承力结构的冲击特性。结果表明:BWB机身在不同冲击速度下客舱区域均基本保持完整,主要破坏发生在客舱地板以下区域,可生存空间得到保持;翼身融合构型民机在坠撞时产生的加速度响应分布呈现由中央过道向机体侧部降低的趋势,且中央过道处的加速度峰值较高;结构吸能方面,隔框是最主要的吸能结构,其次是机身肋板,而货舱立柱未很好的压溃吸能。
Abstract:
Significant differences in structure and layout exist between the Blended Wing Body (BWB) civil aircraft and conventional cylindrical fuselage metal aircraft. As a result, the impact resistance characteristics of the non-circular fuselage structure and the injury mechanisms for occupants remain unclear. A 460-seat BWB aircraft model was developed based on the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) proposed by National Aeronautics and Space Administration (NASA). The aircraft has a wingspan of 80 meters, a range of approximately 16,000 km, a cruising Mach number of 0.85, and a cruising altitude of 11,000 meters. Three typical loading conditions—critical maneuvering loads (2.5g overload and -1.0g overload) and cabin pressurization loads (Double the cabin pressurization load)—were used as input conditions to evaluate the strength and stiffness of the BWB structure. Through iterative structural design optimization, the model was confirmed to meet the typical loading requirements and demonstrated sufficient safety margins. The model included all major structural components of the BWB configuration, such as skin, frames, stringers, cargo floor, cabin floor, support columns, and fuselage ribs. In the finite element modeling process, from the perspective of reducing the amount of calculation, the part of the crash response that had less influence was reasonably simplified, such as the outer wings and engines were simplified as concentrated mass points. The cabin seats and passengers were also modeled as concentrated masses and fixed to the seat rails. The primary structural components of the BWB aircraft model, including the skin, stringers, floor, and floor beams, were constructed from AS4 carbon fiber composite laminates and modeled using shell elements. The pultruded rods were made of AS4 carbon fiber composite and modeled using beam elements. The foam core of the frames and fuselage ribs were made of Rohacell-110-WF foam material and modeled using solid elements. The remaining structures were made of 7075 aluminum alloy and modeled using shell elements. The final model had a total mass of 162.87 tons and consisted of 2,679,991 elements. Five vertical impact velocities ranging from 26 ft/s to 30 ft/s were selected to analyze the cabin space integrity, acceleration response of the cabin floor, and the impact characteristics of the primary load-bearing structures. The results show that the cabin area of the lift-body fuselage remains largely intact under different impact velocities. The primary damage occurs below the cabin floor, with compressive damage concentrated in the lower structures of the middle and aft fuselage. The survivable space is preserved. Compared to a round-section fuselage, the deformation of BWB frames is relatively small, and the upward bulging is not significant, making it difficult to form effective plastic hinges. During the crash, the acceleration load distribution of the blended wing body-integrated aircraft shows a decreasing trend from the central aisle to the sides of the fuselage, with peak acceleration loads being higher at the central aisle. Under all five crash conditions, passenger injury levels in various cabin positions fall within the serious but acceptable and safe regions. Regarding structural energy absorption, the frames serve as the primary energy-absorbing structures, followed by the fuselage ribs. However, the cargo pillars do not effectively crush and absorb energy. For the future crashworthiness design of BWB civil aircraft, the cargo structure should be a key consideration.