“…Therefore, the rigidity and amplification, which are regarded as the key parameters of flexure-hinge mechanisms, are widely investigated by many researchers in recent years [19,20,21,22] . Recently, Tu and Xuan et al [23,24,25,26] developed various extensometers to monitor the creep strain of pipeline at elevated temperature, especially by magnifying mechanisms. However, according to the best knowledge of authors, very few references introduced the deformation monitoring of bolted flange joints during the assemble or operation process, especially the rotation angle of flange.…”