Institut für Mikrotechnik, Technische Universität Braunschweig, 38124 Braunschweig, Germany.
Institut für Mechanik und Adaptronik, Technische Universität Braunschweig, 38106 Braunschweig, Germany.
Sensors (Basel). 2021 Sep 28;21(19):6479. doi: 10.3390/s21196479.
Monitoring process parameters in the manufacture of composite structures is key to ensuring product quality and safety. Ideally, this can be done by sensors that are embedded during production and can remain as devices to monitor structural health. Extremely thin foil-based sensors weaken the finished workpiece very little. Under ideal conditions, the foil substrate bonds with the resin in the autoclaving process, as is the case when polyetherimide is used. Here, we present a temperature sensor as part of an 8 µm thick multi-sensor node foil for monitoring processing conditions during the production and structural health during the lifetime of a construction. A metallic thin film conductor was shaped in the form of a space-filling curve to suppress the influences of resistance changes due to strain, which could otherwise interfere with the measurement of the temperature. FEM simulations as well as experiments confirm that this type of sensor is completely insensitive to the direction of strain and sufficiently insensitive to the amount of strain, so that mechanical strains that can occur in the composite curing process practically do not interfere with the temperature measurement. The temperature sensor is combined with a capacitive sensor for curing monitoring based on impedance measurement and a half-bridge strain gauge sensor element. All three types are made of the same materials and are manufactured together in one process flow. This is the key to cost-effective distributed sensor arrays that can be embedded during production and remain in the workpiece, thus ensuring not only the quality of the initial product but also the operational reliability during the service life of light-weight composite constructions.
监控复合材料结构制造过程中的工艺参数对于确保产品质量和安全至关重要。理想情况下，可以通过在生产过程中嵌入的传感器来实现这一点，这些传感器可以作为监测结构健康状况的设备继续使用。极薄的基于箔片的传感器几乎不会削弱成品工件的强度。在理想条件下，箔片基底会与热压罐过程中的树脂结合，就像使用聚醚酰亚胺时那样。在这里，我们提出了一种温度传感器，它是用于监测生产过程中加工条件和结构在使用寿命期间健康状况的 8 µm 厚多传感器节点箔片中的一部分。金属薄膜导体被成形为空间填充曲线的形式，以抑制由于应变引起的电阻变化的影响，否则这些影响可能会干扰温度的测量。有限元模拟以及实验证实，这种类型的传感器对应变方向完全不敏感，并且对应变的量足够不敏感，因此复合材料固化过程中可能出现的机械应变实际上不会干扰温度测量。温度传感器与基于阻抗测量的固化监测用电容式传感器以及半桥应变计传感器元件相结合。这三种类型都由相同的材料制成，并在一个工艺流程中一起制造。这是在生产过程中可以嵌入并保留在工件中的具有成本效益的分布式传感器阵列的关键，从而不仅确保初始产品的质量，而且还确保轻量级复合材料结构在使用寿命期间的运行可靠性。
