机翼复合材料结构相似缩比模型固化变形研究

发布时间：2018-05-03 11:00

本文选题：复合材料 + 缩比模型　；参考：《大连理工大学》2015年硕士论文

【摘要】：在现代飞机设计工作中,针对飞机缩比物理模型的风洞试验是一项获得飞机气动弹性特征的重要工作。风洞试验中的缩比物理模型是试验的对象,其几何外形特征,气动弹性特征都需要与飞机设计方案保持高度的相似性,从而准确反映飞机设计方案的特点。近些年来,由多相材料复合而成的复合材料,综合发挥了其各组成材料的优点,呈现出了比单一材料更具优势的性能,在航空航天等方面,得到了大量的应用。由于复合材料优异的力学性能可设计性,以复合材料结构为主体的机翼结构相似缩比模型也成为了现代飞机风洞试验研究的热点。本论文研究的树脂基复合材料,均使用热固性树脂作为材料基体,使用模塑成型工艺制造成型。其中,热固性树脂的固化是一个复杂的热学、化学和力学过程,在固化过程中材料力学性能及热物理性能发生急剧变化,而且由于树脂基体和增强纤维的热膨胀系数存在较大的差距,兼之树脂在固化工程中发生了化学收缩,以及模具与复合材料之间的剪切作用等,使得复合材料结构件内部在固化过程中有较大的固化应力,但是由于受到模具型腔的约束,使得复合材料结构内部的固化应力无法得到释放,因此在复合材料固化成型完成,脱离模具型腔之后,复合材料结构内部的固化应力会得到释放,一段时间过后,复合材料结构会出现变形的现象,影响了复合材料结构的外形精度以及相关力学性能。机翼复合材料结构相似缩比模型在固化后会产生变形等现象,影响外形精度,进一步影响模型的气动特性及风洞试验数据的可靠性。本论文首先用应变片测定了环氧树脂、单向复合材料、玻璃纤维正交复合材料与碳纤维正交复合材料等基本材料的固化残余应力及变形情况,求得了等效热膨胀系数,并且做了相应的拉伸试验,得到了需要的力学性能参数。通过建立的研究树脂基复合材料残余应力的理论模型,结合已经得到的相关参数,用理论分析的方法和大型三维软件ANSYS仿真的方法对上述层合板的固化变形进行了分析验证。考虑到传统的试验方法研究风洞试验缩比模型的固化变形将浪费很多的时间和材料,成本增加,因此采用有限元分析方法对固化变形进行分析和预测来代替反复试验。在论文的最后用ANSYS软件建立了有限元模型,对机翼复合材料结构相似缩比模型进行了固化变形预测,为后续改进工艺奠定了基础。
[Abstract]:In the design of modern aircraft, wind tunnel test for the physical model of aircraft shrinkage is an important work to obtain the Aeroelastic characteristics of aircraft. The shrinkage physical model in wind tunnel test is the object of the test. The geometric shape and Aeroelastic characteristics of the model need to keep the height similarity with the aircraft design plan so as to accurately reflect the characteristics of the aircraft design scheme. In recent years, composite materials composed of multiphase materials have brought into full play the advantages of each component material, and have shown more advantages than single materials, and have been widely used in aerospace and other fields. Because of the excellent design of mechanical properties of composite materials, the similar shrinkage model of wing structures with composite structures as the main body has become a hot spot in modern aircraft wind tunnel tests. In this paper, thermosetting resin is used as matrix and molding process is used. The curing of thermosetting resin is a complicated thermal, chemical and mechanical process. Moreover, the thermal expansion coefficient of resin matrix and reinforced fiber has a big gap, and the resin has chemical shrinkage in curing engineering, as well as the shearing effect between mould and composite material, etc. The internal solidification stress of the composite structure is larger in the curing process, but due to the constraints of the mold cavity, the curing stress in the composite structure can not be released, so the solidification molding is completed in the composite material. After leaving the mold cavity, the internal solidification stress of the composite structure will be released. After a period of time, the composite structure will appear the phenomenon of deformation, which will affect the shape accuracy and the related mechanical properties of the composite structure. The similar shrinkage ratio model of wing composite structure will produce deformation after solidification which will affect the shape accuracy and further affect the aerodynamic characteristics of the model and the reliability of wind tunnel test data. In this paper, the curing residual stress and deformation of epoxy resin, unidirectional composite, glass fiber orthogonal composite and carbon fiber orthogonal composite were measured by strain gauges, and the equivalent thermal expansion coefficient was obtained. And the corresponding tensile test was done, and the required mechanical properties were obtained. Based on the theoretical model of residual stress of resin matrix composites and the relevant parameters obtained, the solidification deformation of the laminates was analyzed and verified by the method of theoretical analysis and the simulation of large-scale three-dimensional software ANSYS. Considering that the traditional test method to study the solidification deformation of wind tunnel test shrinkage model will waste a lot of time and materials and increase the cost, the finite element analysis method is used to analyze and predict the solidified deformation instead of repeated tests. At the end of the paper, the finite element model is established by ANSYS software, and the solidification deformation prediction of the similar shrinkage model of wing composite structure is carried out, which lays a foundation for the further improvement of the technology.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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