三维编织复合材料圆管横向冲击变形和细观结构破坏机理

发布时间：2018-05-04 20:08

本文选题：三维编织复合材料圆管 + 横向冲击　；参考：《东华大学》2017年博士论文

【摘要】：三维编织结构复合材料具有增强结构整体性,克服传统层合板复合材料易分层等缺点。三维编织复合材料圆管具有较高剪切强度和抗冲击损伤容限,在航空航天领域潜在应用包括:机身圆筒,尾翼轴,火箭尾喷管,传动轴等,在其它领域应用包括:建筑桁架,机械设备承载件,工业管道,自行车车架,各类球拍杆等。三维编织复合材料圆管在以上应用过程中不可避免受到冲击载荷作用。本文旨在研究三维编织复合材料圆管横向冲击响应,探讨编织结构参数对横向冲击性能影响。通过全尺寸细观结构模型有限元分析方法预测试样横向冲击力学性能、破坏过程、应力分布及传播,发现三维编织结构复合材料横向冲击变形和损伤的细观结构机理。论文主要内容:(1)实验方法研究三维编织复合材料圆管横向冲击性能,获得载荷-位移曲线,位移-时间曲线,能量吸收和最终破坏形态。探讨编织结构参数对三维编织复合材料圆管横向冲击力学响应的影响。编织参数包括编织角(15o、30o和45o),编织层数(2层、3层和4层)和轴纱(4向和5向)。(2)通过细观结构有限元分析方法探讨三维编织复合材料圆管横向冲击加载变形及破坏细观结构机理。分别探讨冲击气压、编织角、编织层数和轴纱对材料冲击损伤机理的影响,包括冲击变形历程,应力分布及传播和最终损伤模式。(3)对比分析实验结果和有限元模拟结果,验证细观结构有限元分析模型的有效性。包括载荷-位移曲线和损伤形态的对比。研究发现:(1)实验结果:冲击气压和编织参数对三维编织复合材料圆管横向冲击力学响应影响显著。随着冲击气压增大,各编织结构试样载荷峰值、位移和能量吸收均增加。随着编织角增大、编织层数增加或轴纱加入,冲击载荷峰值均增大,位移减少。编织角越小、编织层数越多或加入轴纱,试样比吸收能越大。三维编织复合材料圆管横向冲击后主要破坏模式包括:基体碎裂、界面开裂、纤维束断裂及纤维束内部劈裂。小冲击气压下,以纤维束间基体碎裂和界面开裂为主,随着冲击气压增大,纤维束开始断裂。不同编织参数对材料内部损伤机制影响较大。(2)有限元分析结果:应力主要集中在冲击区和握持区,三维编织结构增强体为主要承载组份。变形包括:圆管整体弯曲变形、截面扁化和冲击区局部凹陷。纱线在圆管中的空间状态是影响应力传播的重要因素。沿着圆管轴向,应力在小编织角纱线和轴纱中衰减较慢。随着编织角增大、编织层数增多或加入轴纱,三维编织复合材料圆管的整体性增强,从而提高材料抗冲击变形和损伤能力。(3)模型有效性验证:有限元分析获得的载荷-位移曲线和损伤形态与实验结果吻合良好,从而验证该全尺寸细观结构有限元模型有效性。其中有限元模拟载荷略高于实验结果,而模拟位移略低于实验结果,这是由于有限元模型中未考虑实际材料结构中存在的各类缺陷,如裂纹、孔洞和界面。上述研究主要针对三维编织复合材料圆管横向冲击响应,通过细观结构有限元数值分析法探讨材料受横向冲击加载变形和破坏的细观结构机理。该研究结果对三维编织复合材料圆管的结构设计具有指导价值,并可进一步将此研究方法应用于其它纺织复合材料结构设计的研究中。
[Abstract]:The three-dimensional braided composite material has the advantages of strengthening the integrity of the structure and overcoming the shortcomings of the traditional laminated composite materials. The three-dimensional braided composite circular tube has high shear strength and impact damage tolerance. The potential applications in the aerospace field include the fuselage cylinder, tail shaft, rocket tail nozzle, drive shaft and so on. The use includes: building truss, mechanical equipment loader, industrial pipe, bicycle frame, and all kinds of racket bars. The three-dimensional braided circular pipe is inevitably affected by the impact load during the above application. This paper aims to study the lateral impact response of the three-dimensional braided composite circular pipe, and discuss the influence of the weaving structure parameters to the lateral impact performance. The mechanical properties of transverse impact, failure process, stress distribution and propagation are predicted by the finite element analysis of the full size microstructural model. The main contents of the paper are as follows: (1) the experimental method is used to study the transverse impact of the three-dimensional braided circular tube. Performance, the load displacement curve, displacement time curve, energy absorption and final failure form are obtained. The influence of braiding structure parameters on the transverse impact mechanical response of three-dimensional braided composite circular tube is discussed. The knitting parameters include the braiding angle (15O, 30o and 45o), the number of braiding layers (2 layers, 3 layers and 4 layers) and the axis yarn (4 and 5 directions). (2) through the meso structure The influence of impact pressure, braiding angle, weave layer number and shaft yarn on the damage mechanism of material impact, including impact deformation process, stress distribution and propagation and final damage mode, are discussed respectively. The experimental results are compared and analyzed. (3) experimental results are compared and analyzed. The finite element simulation results are used to verify the effectiveness of the meso structural finite element analysis model, including the load displacement curve and the comparison of damage forms. The results are as follows: (1) the experimental results: the impact pressure and the braiding parameters have significant influence on the lateral impact mechanical response of the three-dimensional braided circular tube. With the increase of the impact pressure, the specimens of each woven structure are loaded. The peak load, displacement and energy absorption increased. With the increase of the knitting angle, the number of braiding layers increased or the axial yarn added, the peak value of the impact load increased and the displacement decreased. The smaller the weaving angle, the more the number of weave layers or the axis yarn, the larger the specimen's absorption energy. The main failure modes after the transverse impact of the three-dimensional braided composite pipe include the matrix fragmentation and the boundary. Fracture of surface, fracture of fiber bundle and internal splitting of fiber bundle. Under the small impact pressure, the matrix fragmentation and interface cracking are mainly in the fiber bundles. With the increase of the impact pressure, the fiber bundles begin to break. The different weaving parameters have great influence on the internal damage mechanism of the material. (2) the finite element analysis results are mainly concentrated in the impact zone and the holding area. The fabric reinforced body is the main bearing component. The deformation includes the whole bending deformation of the circular tube, the cross section and the partial sag in the impact zone. The space state of the yarn in the circular pipe is an important factor affecting the stress propagation. The stress is slow down in the small braided yarn and the axis yarn along the circular tube. With the increase of the knitting angle, the number of weave layers increases. Or adding shaft yarn, the integrity of the three-dimensional braided circular tube is enhanced, thus improving the impact deformation and damage ability of the material. (3) validation of the model validity: the load displacement curve and the damage form obtained by finite element analysis are in good agreement with the experimental results, thus verifying the validity of the finite element model of the full size meso structure. The simulation load is higher than the experimental results, and the simulated displacement is slightly lower than the experimental results. This is due to the various defects in the finite element model, such as cracks, holes and interfaces. The above study is mainly aimed at the transverse punching response of the three-dimensional braided composite circular pipe through the meso structure finite element numerical analysis method. The mesoscopic structure mechanism of material subjected to transverse impact loading deformation and failure is discussed. The results are of guiding value to the structure design of three-dimensional braided circular pipe, and can be further applied to the study of other textile composite structure design.

【学位授予单位】：东华大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB33

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