Composite materials are already being used in the mass production of structural components in the automotive industry, particularly at the BMW Group. Adhesive bonding is generally considered to be the best technique for joining CFRP (carbon fiber reinforced plastic) light-weight structures. The conventional NDT (nondestructive testing) methods currently being used focus on the detection of material defects, e.g. debonding. These methods give little information about the surface properties or bond quality. A new ENDT (extended nondestructive testing) method is the BonNDTinspect system, based on a patent held by the Fraunhofer IFAM. An ultrasonic atomizer nozzle creates a water-aerosol and the small water droplets are sprayed onto the surface. Depending on the surface properties (surface energy or contamination state), the aerosol will form wide or narrow drops on the surface. We determined a test for certain contaminations, including release agents, oil, and fingerprints, the detection of which is critical to ensure the performance of adhesively joined CFRP structures. The BonNDTinspect system is an inline-capable NDT technique that is suitable for distinguishing surface states for adhesive bonding of CFRP. We verify this statement with destructive tests, including the single-lap shear test. It was found by using an extension of the evaluation criteria that it is possible to detect contamination such as water-soluble release agent, CFRP dust and fingerprints. The investigated contamination with hydraulic oil allows only a clear differentiation between cleaned and contaminated. A contamination with corundum is not detectable by the BonNDTinspect system alone.

中文翻译：

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受污染的碳纤维复合材料无损检测与BonNDTinspect表面^®系统

复合材料已经用于汽车工业，特别是宝马集团的结构部件的批量生产中。通常认为，粘接是连接CFRP（碳纤维增强塑料）轻型结构的最佳技术。当前使用的常规NDT（非破坏性测试）方法侧重于检测材料缺陷（例如脱胶）。这些方法几乎没有提供有关表面性质或粘结质量的信息。BonNDTinspect系统是一种新的ENDT（扩展无损检测）方法，该系统基于Fraunhofer IFAM拥有的专利。超声波雾化器喷嘴会产生水雾，并将细小的水滴喷洒到表面上。根据表面性质（表面能或污染状态），气溶胶将在表面形成宽或窄的液滴。我们确定了对某些污染物的测试，包括脱模剂，油和指纹，对这些污染物的检测对于确保粘结CFRP结构的性能至关重要。BonNDTinspect系统是一种可在线使用的NDT技术，适用于区分CFRP粘接的表面状态。我们通过破坏性测试（包括单圈剪切测试）验证了这一说法。通过扩展评估标准，发现可以检测到诸如水溶性脱模剂，CFRP灰尘和指纹等污染物。所调查的液压油污染仅能清楚地区分清洁后的污染物。仅BonNDTinspect系统无法检测到刚玉污染。