冲击位置对复合材料加筋板冲击后压缩行为影响试验

Experimental study on the influence of impact positions on compression-after-impact behavior of composite stiffened panels

  • 摘要: 对低速冲击 (LVI)载荷下不同冲击位置对T型复合材料加筋板损伤容限的影响进行了试验研究。选取了2个典型冲击位置,即:两筋间蒙皮和筋条长桁边缘,引入目视可检冲击损伤(VID)。借助目视及无损检测手段观察到不同冲击位置处的损伤存在显著差异。相比于蒙皮冲击,长桁边缘冲击处的损伤形式更复杂,表现为:纤维断裂、基体开裂、分层、层剥离及界面脱粘。分别对完好、蒙皮冲击和长桁冲击试件进行冲击后压缩试验(CAI)。结果表明:蒙皮冲击件与完好件失效过程极为相似,由于试验夹具刀口的存在,限制了加筋板的变形,诱发了损伤起始,导致最终的结构破坏;而长桁冲击件展示出截然不同的失效机制,损伤从冲击位置沿试件横向扩展,促使结构整体失效的提前发生,显著降低了加筋板的剩余压缩强度。此外,引入数字图像相关技术(DIC)对压缩过程中试件的变形进行监测,并与传统的接触式测量结果进行对比,验证了该测试方法应用于材料力学性能测试的可行性与优越性。

     

    Abstract: The effect of impact positions on the damage tolerance of T-stiffened composite panels was investigated by experimental methods. Low velocity impact (LVI) was carried out at two typical locations, namely the center of skin between two stiffeners and the stiffener flange tip of the panels, to introduce visible impact damage (VID). With the help of visual inspection and nondestructive detection, obvious differences in damage morphology from different impact positions were observed. Compared with the skin impact, the damage types induced by the flange tip impact were more complicated, including fiber fracture, matrix cracks, delamination, ply splitting and interface debonding. Compression-after-impact (CAI) tests were performed on the intact, skin-impacted and flange-impacted stiffened panels respectively. The experimental results show that the deformation of skin-impacted panels is restricted due to blade supports, inducing the damage initiation and causing ultimate destruction, which is extremely similar to intact panels. For the flange tip impact, whilst, damage propagation is along the transverse direction from the impact location, which is entirely different from skin impact in the damage scenario, promoting the structural failure and reducing significantly the residual compressive strength. Additionally, the digital image correlation (DIC) was used to monitor the deformation of the specimens during compression and compared with the results of contact measurement, which verified the feasibility and superiority of the test method applied to the mechanical properties of materials.

     

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