超声波喷丸加筋板成形工艺研究
发布时间：2018-08-07 13:09
【摘要】：加筋板是工程领域常见的轻量化结构,既能减轻结构自重又能满足结构强度和刚度要求,被广泛运用于航空航天等工业领域。目前采用机械喷丸工艺对加筋板进行成形时,存在带筋板区域弯曲变形量不足的问题,亟需开展加筋板新型喷丸成形工艺研究。超声波喷丸技术作为一种新型喷丸工艺,可以获得比传统机械喷丸更大更深的残余压应力场,能大幅提高加筋板喷丸成形弯曲变形量,同时表面质量和成形后综合性能也优于传统机械喷丸,为加筋板提供了一种成形新途径。本文运用超声波喷丸成形工艺,以加筋板为研究对象,在超声波喷丸板件成形理论分析的基础之上,对超声波喷丸加筋板成形的成形量、成形特性以及表面性能进行了研究,并结合数值分析方法对超声波喷丸加筋板成形过程进行了模拟,主要研究工作如下:1.理论分析了超声波喷丸的成形过程。基于Hertz碰撞理论,研究了超声波喷丸过程中板件的变形情况和受力情况,探讨了弹塑性变形前后凹坑直径、凹坑深度和冲击力的大小以及回弹后残余应力沿深度方向的分布关系,分析了残余压应力场的产生过程以及板件弯曲变形和残余应力场的关系,推导了板件成形曲率半径与残余压应力的计算公式。2.对无筋壁板进行了超声波喷丸成形试验,分析了不同喷丸轨迹对无筋壁板曲率半径的影响,研究发现采用展向喷丸轨迹可以在提高壁板弦向变形程度的同时降低展向变形程度,有利于改善壁板球面变形趋势。基于展向喷丸轨迹,对加筋板进行了超声波喷丸成形试验,对影响加筋板成形曲率半径的主要喷丸工艺参数进行了研究,分析了加筋板基本弯曲变形规律。结果表明:在展向喷丸轨迹下,加筋板展向与弦向曲率半径的比值基本在11倍以上,此时加筋板展向变形很小可忽略不计,加筋板近似呈现弦向单曲率变形趋势。同时,还获得了加筋板较优成形工艺参数。3.对超声波喷丸后加筋板试件的表面性能进行了研究,分析了不同喷丸工艺参数对试件表面形貌、表面粗糙度、显微硬度以及残余应力场的影响。结果表明,与未喷丸试件相比,超声波喷丸后,成形件的表面粗糙度有所增加、表面硬度得到增大、并在材料表层产生了呈“√”状分布的有益残余压应力场,这表明了超声波喷丸成形技术是集塑性成形和冲击强化为一体的新工艺。同时,还获得了加筋板较优表面性能参数。4.通过动态仿真与静态仿真相结合的方法,建立了超声波喷丸加筋板成形数值分析模型,利用有限元分析方法,研究了不同喷丸工艺参数对加筋板成形曲率半径以及残余应力场的影响,并将数值分析结果和试验结果进行比较,二者的数据误差很小,验证了有限元模型的可靠性,为研制开发大变形机翼壁板的超声波喷丸成形工艺提供理论及数据参考。
[Abstract]:Stiffened plate is a common lightweight structure in engineering field. It can not only reduce the structural weight but also meet the requirements of structural strength and stiffness. It is widely used in aerospace and other industrial fields. In the process of mechanical shot peening, there is a problem of insufficient bending deformation in the stiffened plate area, so it is urgent to study the new shot peening process of stiffened plate. As a new type of shot peening technology, ultrasonic shot peening technology can obtain a larger and deeper residual compressive stress field than traditional mechanical shot peening, and can greatly increase the bending deformation of shot peening of stiffened plate. At the same time, the surface quality and the comprehensive properties after forming are better than those of traditional mechanical shot peening, which provides a new way for forming stiffened plate. Based on the theoretical analysis of ultrasonic shot peening plate forming, the forming quantity, forming characteristics and surface properties of ultrasonic shot peening plate are studied in this paper. Combined with numerical analysis method, the forming process of ultrasonic shot peening stiffened plate is simulated. The main research work is as follows: 1. The forming process of ultrasonic shot peening is analyzed theoretically. Based on Hertz collision theory, the deformation and stress of plate during ultrasonic shot peening are studied, and the diameter of crater before and after elastoplastic deformation is discussed. The relationship between the depth of the pit and the impact force and the distribution of the residual stress along the depth after springback is analyzed. The process of producing the residual compressive stress field and the relationship between the bending deformation and the residual stress field of the plate are analyzed. The formula of curvature radius and residual compressive stress of sheet metal forming is derived. The ultrasonic shot peening test was carried out on the unstiffened wall plate, and the influence of different shot peening locus on the curvature radius of the unstiffened wall plate was analyzed. It was found that the spanned shot peening trajectory could increase the chordal deformation degree of the wall plate and reduce the spreading deformation degree at the same time. It is beneficial to improve the deformation trend of wall surface. Based on the trajectory of spanned shot peening, the ultrasonic shot peening test of stiffened plate was carried out. The main parameters affecting the curvature radius of stiffened plate were studied, and the basic bending deformation law of stiffened plate was analyzed. The results show that under the trajectory of shot peening, the ratio of spanned and chordal curvature radius of stiffened plate is above 11 times, at this time, the span deformation of stiffened plate can be neglected, and the stiffened plate approximately shows the tendency of chordal single curvature rate deformation. At the same time, the optimum forming process parameters of stiffened plate are obtained. The surface properties of stiffened plate after ultrasonic shot peening were studied. The effects of different parameters of shot peening on the surface morphology, surface roughness, microhardness and residual stress field were analyzed. The results show that after ultrasonic peening, the surface roughness and hardness of the formed parts are increased, and the beneficial residual compressive stress field is produced in the surface layer of the material. This indicates that ultrasonic shot peening is a new technology which integrates plastic forming and impact strengthening. At the same time, the optimum surface performance parameters of stiffened plate. By combining dynamic simulation with static simulation, the numerical analysis model of ultrasonic shot peening plate forming is established, and the finite element analysis method is used. The effects of different parameters of shot peening on the curvature radius and residual stress field of stiffened plate are studied. The numerical analysis results are compared with the experimental results. The data error between them is very small, which verifies the reliability of the finite element model. It provides a theoretical and data reference for the research and development of ultrasonic shot peening process for large deformed wing panels.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG668
本文编号：2170121
[Abstract]:Stiffened plate is a common lightweight structure in engineering field. It can not only reduce the structural weight but also meet the requirements of structural strength and stiffness. It is widely used in aerospace and other industrial fields. In the process of mechanical shot peening, there is a problem of insufficient bending deformation in the stiffened plate area, so it is urgent to study the new shot peening process of stiffened plate. As a new type of shot peening technology, ultrasonic shot peening technology can obtain a larger and deeper residual compressive stress field than traditional mechanical shot peening, and can greatly increase the bending deformation of shot peening of stiffened plate. At the same time, the surface quality and the comprehensive properties after forming are better than those of traditional mechanical shot peening, which provides a new way for forming stiffened plate. Based on the theoretical analysis of ultrasonic shot peening plate forming, the forming quantity, forming characteristics and surface properties of ultrasonic shot peening plate are studied in this paper. Combined with numerical analysis method, the forming process of ultrasonic shot peening stiffened plate is simulated. The main research work is as follows: 1. The forming process of ultrasonic shot peening is analyzed theoretically. Based on Hertz collision theory, the deformation and stress of plate during ultrasonic shot peening are studied, and the diameter of crater before and after elastoplastic deformation is discussed. The relationship between the depth of the pit and the impact force and the distribution of the residual stress along the depth after springback is analyzed. The process of producing the residual compressive stress field and the relationship between the bending deformation and the residual stress field of the plate are analyzed. The formula of curvature radius and residual compressive stress of sheet metal forming is derived. The ultrasonic shot peening test was carried out on the unstiffened wall plate, and the influence of different shot peening locus on the curvature radius of the unstiffened wall plate was analyzed. It was found that the spanned shot peening trajectory could increase the chordal deformation degree of the wall plate and reduce the spreading deformation degree at the same time. It is beneficial to improve the deformation trend of wall surface. Based on the trajectory of spanned shot peening, the ultrasonic shot peening test of stiffened plate was carried out. The main parameters affecting the curvature radius of stiffened plate were studied, and the basic bending deformation law of stiffened plate was analyzed. The results show that under the trajectory of shot peening, the ratio of spanned and chordal curvature radius of stiffened plate is above 11 times, at this time, the span deformation of stiffened plate can be neglected, and the stiffened plate approximately shows the tendency of chordal single curvature rate deformation. At the same time, the optimum forming process parameters of stiffened plate are obtained. The surface properties of stiffened plate after ultrasonic shot peening were studied. The effects of different parameters of shot peening on the surface morphology, surface roughness, microhardness and residual stress field were analyzed. The results show that after ultrasonic peening, the surface roughness and hardness of the formed parts are increased, and the beneficial residual compressive stress field is produced in the surface layer of the material. This indicates that ultrasonic shot peening is a new technology which integrates plastic forming and impact strengthening. At the same time, the optimum surface performance parameters of stiffened plate. By combining dynamic simulation with static simulation, the numerical analysis model of ultrasonic shot peening plate forming is established, and the finite element analysis method is used. The effects of different parameters of shot peening on the curvature radius and residual stress field of stiffened plate are studied. The numerical analysis results are compared with the experimental results. The data error between them is very small, which verifies the reliability of the finite element model. It provides a theoretical and data reference for the research and development of ultrasonic shot peening process for large deformed wing panels.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG668
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