This paper proposes a novel non-contact approach to characterise the high-temperature nonlinear coefficient of thermal expansion (CTE) based on the digital image correlation (DIC) and the induction heating technique (IHT). Through IHT, the test samples can be heated up to high-temperature rapidly and realise ideal isothermal cooling after heating, which is fully verified by the numerical models and the experiments. Then the digital images at different temperatures are recorded by a CCD camera and subsequently analysed by the DIC method to obtain the strain at various temperature. Based on the strain curve and temperature curve, the nonlinear CTE can be computed. Furthermore, the CTE of Alloy 330 at the temperature range of 500–1100 K is measured through the proposed method. Compared with the literature results, the relative error is no more than 6%, which means the approach has high accuracy. In addition, the method is efficient in nonlinear CTE characterisation, and the entire test time of Alloy 330 in this paper is no more than 5 min.

本文提出了一种新颖的非接触式方法，该方法基于数​​字图像相关性（DIC）和感应加热技术（IHT）来表征高温非线性热膨胀系数（CTE）。通过IHT，可以将试样快速加热到高温，并在加热后实现理想的等温冷却，这在数值模型和实验中得到了充分验证。然后，通过CCD摄像机记录不同温度下的数字图像，然后通过DIC方法进行分析以获得不同温度下的应变。根据应变曲线和温度曲线，可以计算出非线性CTE。此外，通过提出的方法测量了合金330在500–1100 K温度范围内的CTE。与文献结果相比，相对误差不超过6％，说明该方法具有较高的准确性。另外，该方法在非线性CTE表征中非常有效，本文中的Alloy 330的整个测试时间不超过5分钟。