复合材料泡沫夹芯结构抗冲击性能研究

发布时间：2018-02-11 23:17

本文关键词： 复合材料泡沫夹芯结构层间增韧准静态压痕低速冲击　出处：《武汉理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：复合材料夹芯结构具有轻质高强的特点,广泛应用于航空航天,交通运输,体育生活多个领域。夹芯结构形式多样,可以根据使用要求设计不同种类的夹芯结构,如高强度,高模量结构,抗冲击结构,防护结构等。对于复合材料夹芯结构,经常受到外来物体冲击或者爆炸冲击等,因此对于扩展复合材料夹芯结构的应用范围,对其抗冲击性能的研究显得尤为重要。目前复合材料夹芯结构主要研究领域是结构的Z向强度以及冲击后的抗压缩强度。从吸能角度来研究提高夹芯结构抗冲击性能研究较少,因此本文立足于提高夹芯结构吸能能力,从而提高复合材料夹芯结构抗冲击性能。本文试验中主要通过测试真空辅助树脂灌注(VARI)工艺制备的方格布添加与不添加表面毡层合板的力学性能,检验层间添加表面毡能否实现层间增韧效果。同时对不同蒙皮材料,即方格布、单向布、三轴向布以及蒙皮材料间添加表面毡的夹芯结构进行准静态压痕力(QSI)试验以及落锤式低速冲击(LVI)试验,检验结构的吸能效率,并对QSI试验替代LVI试验表征夹芯结构抗冲击性进行了讨论。通过对试验数据的分析,我们可以得到以下结论:(1)方格布层间添加表面毡,实现了短纤维层间增韧效果,提高了结构吸能能力。并且由于表面毡对纤维曲率的限制,降低了纤维与树脂之间的拉压应力,降低了结构破坏程度。(2)蒙皮材料的不同对夹芯结构准静态压痕力(QSI)试验结果有很大影响:层间添加表面毡能提高夹芯结构的吸能效率;正交铺层试样中,方格布铺层具有最佳吸能效率,采用方格布与单向布混合的准各向同性铺层(其中方格布铺设于最外层)是准各向同性铺层中吸能效率最佳的铺层。(3)夹芯结构蒙皮材料的不同对落锤式低速冲击(LVI)试验结果有较大影响:层间增韧能避免结构在单一层间发生剧烈破坏,提高结构的损伤阻抗,并且相同厚度的蒙皮,采用层间增韧技术能够提高结构的最大接触载荷以及吸能效率;夹芯结构蒙皮厚度增大对冲击最大接触载荷没有影响,反而会降低结构的吸能效率;铺层角度对不同破坏模式的试样产生不同的作用,方格布以局部纤维断裂为主,铺层角度对结构的吸能效率影响较低,单向布失效模式以分层破坏为主,夹角越小分层面积越小,导致结构吸能效率降低。方格布准各向同性铺层试样具有最佳的吸能效率。(4)夹芯结构LVI与QSI试验破坏机理不同,因此选用QSI预测夹芯结构抗冲击性能具有一定的局限性。
[Abstract]:The composite sandwich structure has the characteristics of light weight and high strength, and is widely used in many fields of aerospace, transportation, sports and life. The sandwich structure has various forms and can be used to design different kinds of sandwich structures, such as high strength. High modulus structures, shock resistant structures, protective structures, etc. For composite sandwich structures, they are often subjected to external impact or explosion shock, so they are used to expand the application of composite sandwich structures. It is very important to study the impact resistance of the sandwich structure. At present, the main research field of the sandwich structure is the Z-direction strength and the compressive strength after impact. There is little research on improving the impact resistance of the sandwich structure from the angle of energy absorption. Therefore, this paper is based on improving the energy absorption ability of the sandwich structure. In order to improve the impact resistance of the sandwich structure of composite materials, the mechanical properties of the square cloth made by vacuum assisted resin perfusion (VARI) process and the non-added surface felt laminates were tested in this paper. Test the effect of interlayer toughening by adding surface felt between layers. At the same time, for different skin materials, that is, square cloth, unidirectional cloth, Quasi static indentation QSI test and falling weight low speed impact LVI test were carried out to test the energy absorption efficiency of the sandwich structure with triaxial cloth and surface felt between the triaxial cloth and the skin material. The impact resistance of sandwich structure characterized by QSI test instead of LVI test is discussed. Through the analysis of test data, we can get the following conclusion: 1) adding surface felt between grid layers, and realizing the toughening effect between short fiber layers. The energy absorption ability of the structure is improved, and the tension and compression stress between the fiber and the resin is reduced because of the limitation of the curvature of the fiber on the surface felt. The results of quasi static indentation test of sandwich structure are greatly affected by the different skin materials: the addition of surface felt between layers can improve the energy absorption efficiency of sandwich structure, and in the orthogonal laminated sample, The square cloth layer has the best energy absorption efficiency, Quasi isotropic laminates with square and unidirectional fabrics (where the grid cloth is laid on the outermost layer) is the best energy absorption layer in the quasi isotropic layer. The different impact of the sandwich structure skin materials on the falling hammer low speed impact. The results of LVI) test have great influence: interlaminar toughening can avoid the severe destruction of the structure in a single layer. The maximum contact load and energy absorption efficiency of the structure can be improved by using interlaminar toughening technology with the same thickness of the skin, and the thickness of the sandwich structure has no effect on the maximum impact contact load. On the contrary, the energy absorption efficiency of the structure will be reduced, and the lamination angle will have different effects on the specimens with different failure modes. The local fiber fracture is dominant in the square grid, and the effect of the laying angle on the energy absorption efficiency of the structure is low. The failure mode of unidirectional cloth is mainly delamination failure, and the smaller the angle is, the smaller the delamination area is, the lower the energy absorption efficiency of the structure is, the better the energy absorption efficiency is. The failure mechanism of the sandwich structure LVI is different from that of the QSI test. Therefore, it is limited to choose QSI to predict the impact resistance of sandwich structure.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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