航天用弱刚度铝合金构件残余应力分布超声无损检测与高能声束原位调控技术

Aluminium alloy structures of weak rigidity are widely used in aerospace products. The concentration of inner residual stress, surface residual stress or welding residual stress can lead to deformation and cracking of the structures. Effective detection, elimination and homogenization of residual stress in the stress concentration area are thus of great importance for improving dimension stability and avoiding welding cracking of the structures..Nondestructive testing of the 3D residual stress distribution can be realized by using ultrasonic critical refracted longitudinal waves for the quantitative testing of structure inner residual stress and its gradient in the horizontal directions, and ultrasonic body waves for these in the vertical direction. Using the relaxation and oscillation effect of elastic wave energy for material lattices, the quantitative in-situ control of structure inner residual stress is achieved by placing the exciter at the stress concentration area, transmitting high energy acoustic waves in aluminium alloy structures and forming closed-loop feedback control with the testing information..On the basis of wave-particle duality, three scientific problems are studied, including the propagation of nonlinear ultrasonic waves in residual stress fields, the relaxation mechanism of elastic waves for material lattices and the time-varying closed-loop control theory of residual stress distribution. Based on these studies, a residual stress ultrasonic testing and regulation theory will be presented, the residual stress gradient testing and distribution array testing and control technology will be renovated, and a space technical specification will be established.

航天产品大量使用弱刚度铝合金构件，内部残余应力不平衡引起构件变形和开裂，表层方向残余应力导致弯曲变形和开裂，法向残余应力导致厚度变形，焊接残余应力导致变形和开裂，无损检测并调控残余应力集中区域而获得低应力平衡状态，可有效提高构件尺寸稳定性和避免焊接开裂。.利用超声临界折射纵波检测构件内部表层方向残余应力及其梯度、利用超声体波检测内部法向残余应力及其梯度，实现残余应力三维分布量化无损检测；把激励器放置在应力集中区域，将高能声波定向注入铝合金内部，与检测信息形成闭环反馈控制，利用弹性波能量对材料晶格的振荡和松弛作用，在构件原位完成内部残余应力的量化调控。.依据弹性波的波粒二象性属性，解决残余应力场中超声波非线性波动规律、材料晶格间约束力的弹性波松弛机理和残余应力分布的时变闭环控制理论三个科学问题，提出残余应力超声检测与调控理论、创新应力梯度分布检测和分布状态阵列调控技术，建立航天专门技术规范。

薄壁或变壁厚弱刚度构件在航空航天领域广泛应用，残余应力引起的变形、开裂、耐腐蚀能力和屈服强度及抗疲劳性能下降等问题日益突出，已经对航空航天产品的可靠性和服役安全产生了不可避免的重要影响。本项目围绕弱刚度铝合金构件开战了弱刚度铝合金构件残余应力分布状态的超声波无损检测理论、高能声束调控机理、闭环调控方法记忆残余应力检测的校准技术等四个方面的研究。本项目组研究了弱刚度各项异性材料内部不同残余应力状态下的超声传播规律解决了梯度量化的难题，针对不同加工工艺的特殊性，研究了机械加工构件内部残余应力高能声束调控规律，给出了残余应力消减和均化控制方法对加工形变的影响规律和对材料物理性能变化的规律，根据加工构件残余应力变化具有滞后的特性，进行了残余应力高能声束闭环调控系统开发，针对不同构件制造工艺的特殊性，分别形成无应力加工技术、无应力焊接技术，这些技术不改变材料组织织构状态和不降低原有材料机械性能，是一种冷态去除残余应力技术，是一种完全创新的残余应力量化调控技术。最终形成了1项国家标准、4项行业标准。根据残余应力检测原理建立超声残余应力检测不确定模型并对残余应力设备进行了绝对校准试验形成了行业校准标准1项。