Method for in-situ measurement of near-consolidation zone temperature profiles for laser-based Automated Fiber Placement (InSiTe)

基于激光的自动纤维放置（AFP）能够使用热塑性基质材料原位生产纤维复合结构，从而消除了对高能耗高压灭菌工艺的需要。此外，进一步的优势来自改进的可回收性以及联锁连接技术。挑战在于实现与高压灭菌工艺相当的机械性能。接合强度是通过热-机械过程控制来设定的，这是理想的基于接合区热-机械条件的知识。然后可以使用已知的模型来预测层间强度，从而可以最大限度地减少耗时和成本高的测试方法，并在必要时提高测试过程中的质量。这里的一个问题是连接区域温度历史的过程测量。而接合区前后的温度可以用红外热像仪记录下来，例如，实际接合区被固结辊覆盖。插入到层压板中的热电偶或光纤传感器只能选择性地测量温度，并且专门用于模型验证，尽管它们也充当干扰点，因此高估或低估了温度。因此，目前还没有方法可以获得连续AFP过程中连接区域内温度历史的经验知识。为此，我们在前期工作中设计了一种新的测量方法，即在固结辊上安装光纤瑞利传感器。这创造了一个应变敏感的外壳表面，与连接区连续接触，从而能够检测热机械条件。因此，本项目的目的是探索嵌入在AFP典型的形状自适应固结辊中的瑞利传感器的热机械灵敏度，从而实现基于激光AFP的温度传感测量方法。为此，将进行纤维嵌入的实验研究以及由此产生的热灵敏度和机械灵敏度。研究结果将用于补偿机械和热扰动，使剩余的应变是热应变。在进一步的研究中，将开发一种基于模型的方法，通过将热应变与温度曲线相关联来校准敏感固结辊。将扰动补偿与基于模型的校准相结合，可以在基于连续辊的制造过程中进行温度检测，例如基于激光的AFP。

Laser-based Automated Fiber Placement (AFP) enables the in-situ production of fiber composite structures using thermoplastic matrix materials, thus eliminating the need for an energy-intensive autoclave process. In addition, further advantages arise from improved recyclability as well as interlocking joining techniques. The challenge is to achieve mechanical properties equivalent to the autoclave process. The joint strength is set by thermal-mechanical process control, which is ideally based on knowledge of the thermal-mechanical conditions in the joining zone. Known models can then be used to predict the interlaminar strengths, so that time-consuming and cost-intensive test methods can be minimized and, if necessary, quality can be improved during the process. One problem here is the in-process measurement of the temperature history in the joining zone. While the temperature before and after the joining zone can be recorded by IR thermography, for example, the actual joining zone is covered by the consolidation roller. Thermocouples or fiber optic sensors inserted into the laminate measure the temperature only selectively and are used exclusively for model validation, although they also act as interference points and therefore overestimate or underestimate the temperature. Accordingly, no method currently exists to obtain empirical knowledge about the temperature history within the joining zone in the continuous AFP process. For this reason, a new measuring method was designed in our own preliminary work, in which the consolidation roller is equipped with fiber-optic Rayleigh sensors. This creates a strain-sensitive shell surface that is in continuous contact with the joining zone and thus enables the detection of thermal-mechanical conditions.Therefore, the aim of this project is to explore the thermal-mechanical sensitivity of Rayleigh sensors embedded in a shape-adaptive consolidation roller typical for AFP, thus enabling the measurement method for temperature sensing in laser-based AFP. To this end, experimental studies of fiber embedding and the resulting thermal and mechanical sensitivities will be conducted. The findings will be used to compensate for mechanical as well as thermal disturbances so that the remaining strains are thermal strains. In further investigations, a model-based method for calibrating the sensitive consolidation roll will be developed by correlating the thermal strains with the temperature curves. Combining the disturbance compensation with the model-based calibration will enable temperature detection in a continuous roller-based manufacturing process, such as laser-based AFP.