非均质壳体流体压力成形机理与缺陷控制方法

Facing the urgent requirements in integrally forming of the new generation rockets tank dome with diameter of 3350mm, and the fundamental problems in manufacturing of inhomogeneous welded sheets, the forming properties of AA2219 welded blanks will be characterized to establish the inhomogeneous plastic constitutive model. The plastic deformation behavior and instable mechanism of inhomogeneous shell under loading of fluid pressure will be revealed. In addition, the microstructure evolution and damage formation mechanism under a whole process of welding-forming-heat treatment will be deeply discussed. The collaborative control methods for controlling the plastic instability as well as the geometrical and mechanical formation of a inhomogeneous shell will be proposed. These theories and methods discovered can be applied as a theoretical foundation for the hydroforming of propellant tank dome, and is positive to overcome the technical problems of wrinkling co-existed with cracking, uneven wall thickness and poor consistency of microstructure and mechanical performance.

针对新一代运载火箭贮箱箱底（直径3.35m）整体成形制造的迫切需求，突破2219铝合金非均质拼焊板流体压力成形的关键科学问题。建立铝合金拼焊板非均质塑性本构模型，揭示流体载荷作用下非均质薄壳复杂变形行为与失稳机理，阐明焊接-成形-热处理全流程制造微观组织演变规律和缺陷形成机制，提出非均质壳体塑性失稳抑制和组织性能控制方法，解决起皱与开裂并存、变形不均和组织性能一致性差的难题，为新一代运载火箭整体贮箱箱底流体压力成形制造提供理论基础。

面向大型运载火箭为提高可靠性和运载效能对整体结构箱底的迫切需求，以及大尺寸、高性能铝合金板难于制备，导致大型铝合金拼焊壳体整体成形存在起皱与开裂、变形不均和组织性能差的技术挑战，提出大尺寸铝合金拼焊板流体压力成形技术。针对非均质曲面壳体整体成形塑性失稳机制和缺陷控制的关键科学问题，揭示了双向应力下拼焊板开裂机制和热处理对接头成形性能的影响规律，建立了铝合金拼焊板热处理和成形匹配的工艺路线，提高了拼焊板均匀变形能力，实现了大尺寸2219铝合金拼焊板组织性能均匀性调控和高性能制备。发明了薄壁曲面件双向加压流体压力成形新技术，提出了控制预胀形状调控变形均匀性方法，实现了坯料变形区应力状态精确调控，解决了超大、超薄曲面件整体成形起皱和开裂并存的国际性难题。揭示了变形区失稳机理，建立了薄壳起皱压力和破裂压力理论模型，提出了流体压力非线性加载与缺陷控制方法，建立了流体压力加载工艺窗口，解决了大流量、非线性流体压力-位移实时闭环精确控制和成形缺陷控制的难题，突破了薄壁曲面件整体成形厚径比<3‰的传统技术极限。在国际上首次采用与构件等厚度拼焊薄板直接成形出3m级整体箱底构件，实现了整体箱底构件形状和性能一体化控制，发明的非均质薄壁壳体双向可控加压流体压力成形新方法颠覆了传统技术路线，为大尺寸整体薄壁曲面构件流体压力成形制造提供理论基础。研究成果在火箭、飞机、高铁、汽车等量大面广的各类曲面构件制造中具有广阔的应用前景。