弹性固体残余应力场的原位声能控制机理

The residual stress will be occurred in in-service large mechanical components, including metal truss structure, hull, pressure vessels, structural parts, machine body, car body, guide rail and so on, because of the environment and conditions restrictions, it's impossible or difficult to use such the raditional methods as tempering, loading, impact vibration to relieve or change the state of the residual stress. Therefore, it is urgently necessary to propose a method to relieve or control the profile of residual stress in situ..We study the effect of high energy acoustic field and the physical mechanism of material residual stress relaxation, investigate the mechanism of high energy acoustic field wave energy to break or reconstruct binding force between lattices in material, probe the control mechanism on micro, meso, and macro state of cross-scale residual stress. It preliminarily forms that control theory of residual stress based on ultrasonic wave theory. It will provide a simple and effective method to relieve or control residual stress, and realize the control of residual stress profile for in-service mechanical components..The achievements will provide a control theory of residual stress and a simple and effective control technology, though the high energy acoustic beam and acoustic excitation mode controlling effectively, it will realize the partial quantitative focus for acoustic beam in the internal component, the control application for relieving, suppression and reconstruction of residual stress profile in situ for part of in-service mechanical components, and it will increase the overall strength, fatigue resistance and corrosion resistance for in-service mechanical components, and enhance service life, safety and reliability of component.

受现场使用环境和条件限制，服役大型金属桁架结构、船体、压力容器、结构件、机体、车体、导轨等机械构件出现残余应力时，无法或很难用回火、载荷法、冲击振动法等传统方法消除或改变残余应力状态，因此，迫切需要研究残余应力分布的在原位消除或控制方法。 .研究高能声场与材料残余应力场的作用机理，探讨高能声场波动能量松弛或重建材料晶格间约束力的物理过程，分析微观、介观和宏观跨尺度残余应力的调控原理，形成基于超声波传播和弹性能作用的残余应力调控理论，寻找一种消除和控制残余应力的简便而有效的方法，实现对在役机械构件残余应力分布的调控。.通过有效控制高能声束和声激励模式实现声束在构件内部的局部定量聚焦，实现对在役机械构件局部残余应力分布的原位消除、抑制和重建等调控作用，提高服役机械构件整体强度、抗疲劳和耐腐蚀能力，增强构件使用寿命、安全性和可靠性。

残余应力对机械构件的服役性能具有重大影响，尤其是对其强度、疲劳寿命和尺寸稳定性。为了消除大型构件表面或一定深度内的残余应力，本项目对残余应力高能超声调控理论进行了研究。从两个方面阐释了高能超声调控残余应力的机理。一是研究了高能超声对位错的微观作用，建立了高能超声对晶格位错松弛作用的数学表达式；二是分析了高能超声对材料的宏观塑性诱导效应，通过塑性诱导仿真与实验，证实了高能超声能降低材料的屈服强度，激活错排原子，加快残余应力的消减过程。. 开发与建立了残余应力超声检测与调控的软硬件系统。对声时差测量的不同算法组合进行了Matlab仿真，考虑了耦合剂薄膜厚度不均，以及被测件厚度不同带来的误差，提出了声时差优化算法。创新地将检测与调控系统结合，通过设计ZTC4钛合金的应力闭环调控实验，初步实现了残余应力检测与调控的闭环控制。.在残余应力超声调控原理基础上，采用三种典型材料，研究了各因素对不同材料应力调控的影响规律，得到最佳调控参数。同时还研究了高能超声对材料硬度、强度和金相组织的影响，验证了残余应力高能超声调控理论。. 最后，利用研发的残余应力超声检测与调控系统，开展了针对铝合金焊接与铆接件、结构钢焊接件以及非金属件的残余应力检测与调控工程应用研究。根据现场应用的经验与效果，分别制定了检测工艺规范与调控工艺规范，为大型服役构件的残余应力难以消除的问题提供了一个有效手段。