复合材料折叠夹芯结构制备及力学性能研究

发布时间：2018-06-29 19:45

本文选题：复合材料折叠夹芯层 + DSC分析　；参考：《大连理工大学》2015年硕士论文

【摘要】：作为新型的夹芯结构,复合材料折叠夹层结构具有比强度高,比刚度大和良好的吸能性等特点,有望取代传统蜂窝夹层结构作为航空航天器的主承力结构材料。本文的目的是通过实验手段探索一种简单可行的复合材料折叠夹芯结构芯材制备方法,从而实现芯材制备批量化、标准化和高效率生产,使得该结构在工程应用中占有一席之地。并找到不同材质以及结构、尺寸对其压缩性能的影响规律,为该类结构材料的理论研究与实际应用提供可靠的依据。针对这一目标,选取热压工艺作为制备手段。本次研究从复合材料的固化动力学出发,选择C-03P-200碳纤维和Kevlar-49两种不同性质的平纹编织预浸料作为研究对象。基于热压过程温度、时间、压力三要素,本文对工艺参数进行了优化选取。首先通过对两种预浸料进行5℃、10℃、15℃.20℃的非等温DSC扫描热分析,然后通过外推法确定预浸料最佳的凝胶温度、热压固化温度和后处理温度。在此基础上,对材料进行了DSC等温(凝胶温度、固化温度)扫描热分析,然后以固化动力学的基本原理为依据,确定了预浸料固化度随时间的变化曲线,并结合凝胶试验结果,初步确定了固化各阶段所需要的时间。设计并制造了一套热压模具,对折叠芯子进行了制备,并以芯材的抗压强度、质量、生产效率为目标,利用正交试验、极差分析法,分别对固化工艺各阶段的保温时间和工艺压力进行了优化选取。在压缩性能试验中,分别对不同厚度的芯子、不同约束条件下的夹芯结构、不同材料组合形式多层折叠夹芯结构进行了静态的压缩试验。首先,通过改变芯壁的厚度,研究了芯子随相对密度变化的压缩力-位移变化规律及变形失效形式。最后对折叠夹芯结构、多层结构的折叠夹芯结构进行静态压缩试验,得到了折叠夹芯结构在静态压缩载荷作用下的力-位移变化曲线、破坏模式,进而对其力学特性及吸能特性进行了评估研究。为了探究不同几何尺寸的折叠夹芯结构在压缩载荷下的力学性能和吸能特性变化规律,利用ANSYS/ADPL进行数值化建模,使用LS/dyna有限元软件,采用Chang-Chang和Tsai-Wu失效准则分别对碳纤维和凯夫拉复合材料折叠夹芯结构进行准静态数值模拟研究,经过与试验对比分析其可靠性。最后对芯材长度折叠半角、宽度折叠半角,芯子高度、折叠边长和厚度对整个结构承受峰值压力、吸能特性的影响规律进行了讨论。
[Abstract]:As a new type of sandwich structure, the folded sandwich structure has the characteristics of high specific strength, large specific stiffness and good energy absorption. It is expected to replace the traditional honeycomb sandwich structure as the main bearing structural material of the aerospace vehicle. The purpose of this paper is to explore a simple and feasible composite sandwich core structure core through experimental methods. The preparation method of material has made the preparation of the core material batch, standardization and high efficiency production, which makes the structure occupy a place in the engineering application, and finds the influence law of different material and structure and size on its compression performance. It provides a reliable basis for the theoretical research and practical application of this kind of structure material. The hot pressing process is used as a preparation method. From the curing kinetics of the composite material, two kinds of plain weave prepreg with different properties of C-03P-200 carbon fiber and Kevlar-49 are selected as the research object. Based on the temperature, time, and pressure three factors of the hot pressing process, the process parameters are optimized. First of all, two kinds of preconditioning are adopted. The dipping was analyzed by non isothermal DSC scanning thermal analysis at 5, 10 and 15.20 C. Then the optimum gel temperature, hot pressing temperature and post treatment temperature were determined by extrapolation. On this basis, the DSC isothermal (gel temperature, curing temperature) scanning thermal analysis was carried out on the basis of the basic principle of curing kinetics. The change curve of the curing degree of prepreg with time is determined, and the time required for each stage is preliminarily determined with the result of gel test. A set of hot pressing die is designed and manufactured, the folding core is prepared, and the compression strength, quality and production efficiency of the core material are taken as the target, and the orthogonal test and the difference analysis method are used to separate the solid. In the compression performance test, the static compression test is carried out on the core of different thickness, the sandwich structure under the different constraint conditions and the multi-layer folding sandwich structure with different material combinations. First, the core is studied by changing the thickness of the core wall. In the end, the static compression test is carried out on the folded sandwich structure and the folded sandwich structure of multilayer structure. The force displacement curve and the failure mode of the folded sandwich structure under the static compression load are obtained, and then the mechanical properties and energy absorption characteristics of the folded sandwich structure are also carried out. In order to investigate the mechanical properties of the folded sandwich structures with different geometric sizes under the compression load and the change of the energy absorption characteristics, the numerical modeling was carried out by ANSYS/ADPL. The LS/dyna finite element software was used to use the Chang-Chang and Tsai-Wu failure criteria to carry out the folding sandwich structure of carbon fiber and Kevlar composite materials respectively. The reliability of the quasi-static numerical simulation is compared with the test. Finally, the influence law of the peak pressure on the whole structure and the energy absorption characteristic of the whole structure is discussed by the length folded half angle of the core, the width of the folded half angle, the height of the core, the fold length and the thickness.
【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】：TB33

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