Amif Md Admay, Jack David A
Department of Mechanical Engineering, Baylor University, Waco, TX 76706, USA.
Materials (Basel). 2024 Apr 25;17(9):2002. doi: 10.3390/ma17092002.
Carbon fiber reinforced polymer (CFRP) composites are popular materials in the aerospace and automotive industries because of their low weight, high strength, and corrosion resistance. However, wrinkles or geometric distortions in the composite layers significantly reduce their mechanical performance and structural integrity. This paper presents a method for non-destructively extracting the three-dimensional geometry, lamina by lamina, of a laminated composite. A method is introduced for fabricating consistent out-of-plane wrinkled CFRP laminate panels, simulating the in-service wrinkle observed in industries that utilize thick structure composites such as the vertical lift or wind power industries. The individual lamina geometries are extracted from the fabricated coupon with an embedded wrinkle from captured ultrasonic waveforms generated from single-element conventional ultrasonic (UT) scan data. From the extracted waveforms, a method is presented to characterize the wrinkle features within each individual lamina, specifically the spatially varying wrinkle height and intensity for the wrinkle. Parts were fabricated with visibly undetectable wrinkles using a wet layup process and a hot press for curing. Scans were performed in a conventional immersion tank scanning system, and the scan data were analyzed for wrinkle detection and characterization. Extraction of the layers was performed based on tracking the voltage peaks from A-scans in the time domain. Spatial Gaussian averaging was performed to smooth the A-scans, from which the surfaces were extracted for each individual lamina. The extracted winkle surface aligned with the anticipated wrinkle geometry, and a single parameter for quantification of the wrinkle intensity for each lamina is presented.
碳纤维增强聚合物（CFRP）复合材料因其重量轻、强度高和耐腐蚀等特性，在航空航天和汽车工业中是常用材料。然而，复合材料层中的褶皱或几何变形会显著降低其机械性能和结构完整性。本文提出了一种逐层无损提取层压复合材料三维几何形状的方法。介绍了一种制造平面外褶皱一致的CFRP层压板的方法，以模拟在垂直升降或风力发电等使用厚结构复合材料的行业中观察到的实际使用中的褶皱。通过从单元素传统超声（UT）扫描数据生成的捕获超声波形中，从带有嵌入式褶皱的制造试样中提取各个层的几何形状。从提取的波形中，提出了一种表征每个单独层内褶皱特征的方法，特别是褶皱在空间上变化的高度和强度。使用湿法铺层工艺和热压固化制造出具有肉眼不可见褶皱的部件。在传统的浸入式槽扫描系统中进行扫描，并对扫描数据进行分析以检测和表征褶皱。基于在时域中跟踪A扫描的电压峰值来进行层的提取。进行空间高斯平均以平滑A扫描，从中提取每个单独层的表面。提取的褶皱表面与预期的褶皱几何形状对齐，并给出了用于量化每个层褶皱强度的单个参数。
