双向梯形夹芯板对压成形的数值模拟研究

发布时间：2018-04-24 13:37

本文选题：夹芯板 + 双向梯形　；参考：《吉林大学》2017年硕士论文

【摘要】：夹芯板作为重要的轻量化材料,由于具有高比强度、高比刚度、优良的抗冲击性能等优点,被广泛地应用于航天、航空、交通运输、建筑等许多领域,近年来,对夹芯板曲面有很大需求。目前,夹芯复合板曲面主要通过真空胶接固化法制备,力学性能受限于胶粘剂,容易发生脱胶和老化,使其应用范围受到限制。从现有公开的文献来看,尚未出现有夹芯板直接曲面成形的研究,因此对夹芯板开展成形方面的研究具有重要的现实意义。双向梯形夹芯板是一种新型复合板,采用双向皆有梯形凸凹波纹的铝合金板作为夹芯,克服了传统复合板夹芯不连续的问题,使得夹芯板获得更好的抵抗不同方向变形的承载能力。本文以双向梯形夹芯板为研究对象,主要通过数值模拟的方法,对夹芯板对压成形曲面过程中的变形特点、规律以及主要缺陷形式等方面进行了研究,主要内容如下:1.建立了双向梯形夹芯板对压成形数值模拟的有限元模型,对上、下面板及夹芯的变形和应力分布进行分析,发现焊接区的应力和应变均小于悬空区,胞元的变形主要集中在过渡曲面区域。对比分析了正交两个方向上梯形台斜面与顶面间夹角在不同半径的球面成形过程中的变化值差异,说明了夹芯的各向异性。2.分析了夹芯板曲面成形的主要成形缺陷。通过观察不同曲率半径成形件的形貌特征,发现夹芯板柱面成形过程中的成形缺陷主要有凹陷、局部直面效应以及折皱三种形式,夹芯板球面的成形缺陷主要有起皱、局部直面效应以及夹芯侧壁屈曲三种形式。3.分析了截面参数对柱面成形结果的影响。分析了上面板的失稳凹陷,探讨上面板厚度和夹芯高度对成形质量的影响;分析了下面板的光顺性,探究下面板厚度对悬空区直面效应的影响;分析了夹芯板柱面的应变分布,研究焊接区在弯曲方向上的长度对上面板起皱的影响。4.进行双向梯形夹芯板柱面对压成形实验,检验成形效果,并验证数值模拟的可靠性。运用三维扫描仪PRO CMM对实验件进行测量,并进行曲面和截面进行误差分析,均表明夹芯板具有较高的成形精度。
[Abstract]:As an important lightweight material, sandwich panel has been widely used in many fields such as aerospace, aviation, transportation, construction and so on, because of its advantages of high specific strength, high specific stiffness, excellent impact resistance, etc. In recent years, sandwich panels have been widely used in many fields, such as aerospace, aviation, transportation, construction and so on. There is a great demand for sandwich panel surfaces. At present, the surface of sandwich composite plate is mainly prepared by vacuum bonding curing method. The mechanical properties are limited by adhesive, and it is easy to take place degumming and aging, which limits its application scope. According to the published literatures, there has not been any research on the direct surface forming of sandwich panels, so it is of great practical significance to study the forming of sandwich panels. Two-way trapezoidal sandwich board is a new type of composite board. The aluminum alloy plate with trapezoid convex and concave ripples is used as the sandwich core, which overcomes the problem of discontinuity of sandwich core in traditional composite plate. The sandwich panel has better bearing capacity to resist deformation in different directions. In this paper, the bidirectional trapezoidal sandwich plate is taken as the research object. The deformation characteristics, rules and main defect forms of the sandwich panel in the process of forming the curved surface are studied by means of numerical simulation. The main contents are as follows: 1. A finite element model for numerical simulation of bidirectional trapezoidal sandwich panels is established. The deformation and stress distribution of upper and lower plates and sandwich cores are analyzed. It is found that the stress and strain in the welding area are smaller than those in the suspended zone. The cell deformation is mainly concentrated in the transition surface region. The difference of the angle between the inclined plane and the top plane of the trapezoid platform in two orthogonal directions in the process of spherical forming with different radii is analyzed, and the anisotropy of the sandwich core is explained. The main forming defects of sandwich panel surface forming are analyzed. By observing the shape characteristics of different curvature radius forming parts, it is found that there are three kinds of forming defects in the forming process of sandwich plate cylinder, such as depression, local straight surface effect and wrinkle, and the forming defects of sandwich plate spherical surface are mainly wrinkled. Local straight face effect and buckling of core lateral wall. The influence of section parameters on the results of cylindrical forming was analyzed. The influence of the thickness of the upper panel and the height of the sandwich core on the forming quality is analyzed, the fairing of the lower panel is analyzed, the influence of the thickness of the lower panel on the straight face effect in the suspended area is explored, and the strain distribution of the cylindrical surface of the sandwich panel is analyzed. The effect of the length of welding zone in bending direction on the wrinkling of the upper panel was studied. The forming effect and reliability of numerical simulation were verified by the experiments of face forming of two way trapezoidal sandwich plate columns. The 3D scanner PRO CMM is used to measure the experimental part, and the error analysis of curved surface and section shows that the sandwich plate has high forming accuracy.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG306

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