X-cor夹层结构抗冲击性能研究

发布时间：2018-03-23 15:22

本文选题：Z-pin　切入点：X-cor夹层结构　出处：《南京航空航天大学》2017年硕士论文

【摘要】：X-cor夹层结构是由Z-pin增强泡沫制备的一种新型复合材料夹层结构,本身具有丰富的可设计性,在航空航天、航海、列车等领域有着广阔的应用前景。目前国内外对于X-cor夹层结构抗冲击性能的研究并不多。本文首先研究低速冲击实验对X-cor夹层结构的抗冲击性能的影响,探索其损伤机理、Z-pin增强机制,并研究设计参数的影响规律;接着用有限元对X-cor夹层结构低速冲击以及冲击后剩余压缩强度进行全程模拟;最后,对X-cor夹层结构设计三因素三水平正交试验进行高速冲击,分析其弹道极限和损伤面积,得到在高速冲击工况下最优化的参数设计组合。低速冲击实验中包括:1.低速落锤冲击实验,2.红外无损检测实验,3.冲击后剩余压缩强度实验(CAI)。研究四种设计参数:泡沫类型、Z-pin植入间距、Z-pin排列方向、Z-pin植入角度对X-cor夹层结构抗冲击性能的影响。实验表明:在高能量冲击下,较弱的泡沫芯材反而吸能效果更好;在低冲击能量范围内,减小Z-pin植入间距能够明显降低冲击分层损伤面积;就Z-pin排列方向而言,四向排列的Z-pin抗冲击能力略优于双向排列的Z-pin;Z-pin植入的角度为22°时X-cor夹层结构的抗冲击性能最好。应用商业有限元软件ABAQUS建立了X-cor夹层结构的低速冲击模型,引入Crushable Foam泡沫弹塑性本构模拟泡沫夹芯,采用非线性梁单元对Z-pin进行模拟,结合二维Hashin准则建立了复合材料面板粘弹性损伤本构模型。将冲击后的结果通过数值传递直接用于剩余压缩强度的计算,实现低速冲击到剩余压缩强度的全程模拟。模拟结果表明:冲击模拟得到的分层面积大小相比试验结果较为接近,误差不超过10%;在高能量冲击下,泡沫吸能在冲击能量的吸收中贡献最大;剩余压缩强度模拟中,侧压峰值力模拟值比试验值偏高。通过三因素(面板厚度、泡沫类型、Z-pin植入间距)三水平正交实验探究X-cor夹层结构在高速冲击下的最佳设计参数,分析其失效机理,结果表明:X-cor夹层结构面板的厚度对高速冲击的弹道极限的影响最大,厚度越大弹道极限越大,但不可避免的会带来重量增加;其次是Z-pin植入密度对其弹道极限的影响,Z-pin植入间距最佳设计应不大于冲击物冲头半径;增加泡沫密度对弹道极限影响较小;在三个因素中,Z-pin植入间距对X-cor夹层结构损伤面积的减小影响最大,因此综合考虑,最佳设计水平采用面板厚度2mm、泡沫类型为71IG、Z-pin植入间距为5×5mm。
[Abstract]:X-cor sandwich structure is a new type of composite sandwich structure prepared from Z-pin reinforced foam. At present, there are few researches on the impact resistance of X-cor sandwich structure in China and abroad. First of all, the impact of low speed impact test on the impact performance of X-cor sandwich structure is studied in this paper. To explore its damage mechanism and Z-pin enhancement mechanism, and to study the influence of design parameters; then to simulate the low speed impact and residual compressive strength of X-cor sandwich structure by finite element method. Finally, The design of X-cor sandwich structure with three factors and three levels of orthogonal test was carried out at high speed, and its ballistic limit and damage area were analyzed. The optimal parameter design combination under high speed impact condition is obtained. The low speed impact experiment includes 1: 1. Low speed drop hammer impact experiment 2. Infrared nondestructive testing experiment 3. The residual compression strength after impact test is studied. Four design parameters are studied. The effect of Z-pin placement angle on the impact resistance of X-cor sandwich structure under high energy impact is studied. In the low impact energy range, decreasing the spacing of Z-pin implantation can significantly reduce the impact delamination damage area. For the direction of Z-pin arrangement, The impact resistance of four-direction Z-pin is slightly better than that of bi-directional Z-pinn Z-pin implantation with 22 掳angle. The low speed impact model of X-cor sandwich structure is established by commercial finite element software ABAQUS, and the impact resistance of X-cor sandwich structure is better when the angle is 22 掳. The Crushable Foam foam elastoplastic constitutive model is introduced to simulate the foam sandwich core, and the nonlinear beam element is used to simulate the Z-pin. The viscoelastic damage constitutive model of composite panel is established by using two-dimensional Hashin criterion. The results after impact are directly used to calculate the residual compressive strength by numerical transfer. The simulation results show that the stratified area obtained by the impact simulation is close to the experimental results, and the error is not more than 10. In the simulation of residual compression strength, the simulated value of peak lateral pressure force is higher than the experimental value. The optimum design parameters of X-cor sandwich structure under high speed impact were investigated by three-level orthogonal experiment. The failure mechanism was analyzed. The results show that the thickness of the panel of the sandwich structure has the greatest influence on the ballistic limit of high velocity impact. The greater the thickness, the greater the ballistic limit, but it will inevitably bring about an increase in weight, secondly, the influence of Z-pin implantation density on its ballistic limit. The optimum design of Z-pin insertion spacing should not be greater than the impact impact radius. Increasing foam density has little effect on ballistic limit, and Z-pin implantation spacing has the greatest effect on the reduction of damage area of X-cor sandwich structure. Therefore, considering the optimum design level, the thickness of panel is 2mm, the foam type is 71IGZpin implantation distance is 5 脳 5mm.
【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】：TB33

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