Wind turbine blade certification requires static and fatigue testing at a large‐scale facility similar to the Wind Technology Testing Center (WTTC) located in Charlestown, Massachusetts. Usually, these tests are conducted by using wire‐based sensors such as strain gages, accelerometers, and string potentiometers. These systems are expensive, require a time‐consuming installation (e.g., up to 3 weeks and $35 k–$50 k for a strain gage system on a 55‐m‐long blade), are difficult to deploy on large‐sized structures, require additional instrumentations (e.g., power amplifiers and data acquisition systems), and produce results only at a handful of a discrete number of measurement points. In this study, a multicamera measurement system is implemented and experimentally evaluated to obtain full‐field displacement and strain over a ~12‐m‐long portion of a ~60‐m utility‐scale wind turbine blade. The proposed system has the potential to streamline the certification process by reducing the blade's preparation and sensor installation cost and time to a few hundreds of dollars (for painting equipment) and a few days for preparing the surface of the blade for the test. Furthermore, operational modal analysis was used in conjunction with the multicamera system to estimate the natural frequencies and mode shapes of the wind turbine blade. The obtained results have shown that the proposed approach can detect in‐plane displacement as low as 0.2 mm, mechanical strain with an error below 3% when compared with measurement performed using strain gages, and the first five natural frequencies with an error below 2% when compared with data recorded using traditional wire‐based accelerometers. This paper presents these results and provides a summary of the strengths and weaknesses of the proposed optical measurement approach in the context of streamlining the blade certification/testing process and performing vision‐based structural dynamic measurements on large‐scale structures.

中文翻译：

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多摄像机测量系统，用于评估公用事业规模的风力涡轮机叶片的动态响应

风力涡轮机叶片认证要求在大型设施中进行静态和疲劳测试，类似于位于马萨诸塞州查尔斯敦的风力技术测试中心（WTTC）。通常，这些测试是通过使用基于线的传感器（例如应变计，加速计和弦电位计）进行的。这些系统价格昂贵，需要耗时的安装（例如，对于55米长的刀片上的应变计系统，最多需要3周的时间，并且需要花费$ 35 k– $ 50 k），难以部署在大型结构上，需要其他仪器（例如，功率放大器和数据采集系统），并且仅在少数几个离散的测量点上产生结果。在这个研究中，实施了多摄像机测量系统并进行了实验评估，以获取约60 m公用事业规模风力涡轮机叶片的约12 m长部分的全场位移和应变。拟议的系统有可能通过将刀片的准备和传感器安装成本以及时间减少到几百美元（对于涂装设备）和几天的时间来准备用于测试的刀片表面，从而简化认证过程。此外，运行模态分析与多摄像机系统结合使用，可以估算风力涡轮机叶片的固有频率和模式形状。所得结果表明，与使用应变计进行的测量相比，该方法可以检测到平面内位移低至0.2 mm，机械应变，且误差低于3％，与使用传统的基于线的加速度计记录的数据相比，前五个固有频率的误差低于2％。本文介绍了这些结果，并在简化叶片认证/测试过程以及对大型结构执行基于视觉的结构动态测量的背景下，总结了所提出的光学测量方法的优缺点。