平纹编织复合材料层压板低速冲击损伤特性研究

发布时间：2017-12-27 21:02

本文关键词：平纹编织复合材料层压板低速冲击损伤特性研究　出处：《南昌大学》2016年硕士论文　论文类型：学位论文

【摘要】：平纹编织复合材料由于其高比强度、面内性能好等优点,在航空、航天、机械及军工领域得到了广泛应用。但和传统复合材料一样,在遭受低速冲击后,其材料内部会因为基体开裂、分层和纤维断裂等原因导致其某些性能的下降,影响结构的承载力和安全使用寿命。本文对T700SC-12k-50C/#2510平纹编织复合材料层压板的低速冲击损伤问题开展了研究:通过低速冲击试验,研究三种典型铺层层压板的低速冲击特性;采用ABAQUS有限元软件对层压板冲击过程进行模拟仿真,研究其损伤特点;通过冲击后压缩试验,研究了剩余强度与冲击能量的关系及温湿度环境的影响。(1)确定了三种典型铺层层压板的临界冲击能量,超过该能量时,正面会出现不同深度的凹坑和裂纹,背面则出现纤维断裂。凹坑深度曲线会因纤维断裂出现明显的拐点,三种层压板由于厚度和铺层的不同出现拐点时对应的冲击能量也不相同,发生拐点后,基体开裂严重。(2)引入Hashin面内损伤判据和层间cohesive单元模拟了低速冲击过程对层压板内部造成的损伤。建立了只考虑层压板面内损伤和同时考虑面内、层间损伤的两种模型,前者的纤维断裂和基体开裂损伤通常发生在受冲击的中心位置处沿板宽度?45?方向,在受损伤严重时会呈现“X”形;后者损伤区域会呈现类似双叶、花生等形状,分层损伤是由层压板的冲击背面开始并向着冲击正面发展的,正面的分层损伤面积与背面相比较小,但损伤程度深。数值模拟的损伤面积与超声C扫描得到的损伤投影面积结果基本吻合。(3)确定了冲击能量与剩余强度的关系:冲击能量越大,冲击损伤越严重,剩余强度下降得越多,层压板的承受压缩载荷的能力越差。低速冲击并不影响压缩失效的模式,出现了分层扩展、屈曲等损伤扩展现象,最终发生剪切分层失效。但是其失效特征以及失效区域不同。(4)在同一冲击能量作用下,吸湿后的试件由于脆性下降,比未吸湿的试件对冲击作用更不敏感,但层压板的剩余压缩强度会明显下降。
[Abstract]:Plain weave composites have been widely used in aviation, aerospace, mechanical and military fields because of their high specific strength and good in-plane properties. However, after being subjected to low velocity impact, the properties of the composites will decrease due to cracking, delamination and fiber breakage, which will affect the performance and safety life of the composite. The impact of the T700SC-12k-50C/#2510 plain weave composite laminates damage is studied by low velocity impact test, low impact characteristics of three typical paving laminates; using ABAQUS finite element software to simulate the impact process of laminate, study the damage characteristics; through the compression after impact test, the influence of residual strength and impact energy and the relationship between temperature and humidity environment. (1) the critical impact energy of three typical laminated laminates is determined. When the energy exceeds this energy, there will be different depths of pits and cracks, and fiber breakage will appear on the back side. The dent depth curve will have obvious inflection point due to fiber fracture. The impact energy of the three laminate plates is different when the inflection point occurs due to the thickness and ply difference. After the turning point, the matrix cracking is serious. (2) the damage criterion in the Hashin surface and the interlayer cohesive element are introduced to simulate the damage caused by the low velocity impact process to the laminates. Established only consider laminate in-plane damage and considering the in-plane and interlaminar damage of the two models, the fiber breakage and matrix cracking damage usually occurs in the width of the center position by the impact plate along the 45 direction??, in serious injury may occur when the "X" shape; the latter will damage area similarly, double peanut shape, delamination is the impact on the back of laminate and start toward the positive impact the development of delamination area and positive phase back is relatively small, but the damage degree of depth. The damage area of the numerical simulation is in agreement with the result of the damaged projection area obtained by the ultrasonic C scan. (3) the relationship between impact energy and residual strength is determined. The larger the impact energy is, the more serious the impact damage is, and the more the residual strength decreases, the worse the compressive capacity of the laminate will be. The low velocity impact does not affect the mode of the compression failure, and the damage expansion, such as delamination expansion, buckling, and so on appears, and the shear layering failure occurs eventually. But the failure characteristics and the failure area are different. (4) under the same impact energy, the fragility of specimens after moisture absorption is more insensitive to impact than UNWETTING specimens, but the residual compressive strength of laminates will decrease significantly.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB33

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