China will further reduce the cost of smart bolts

The China Academy of Engineering Physics has brought smart bolts that can detect preload. Fasteners such as bolts have a yield point, which is related to the state of machine operation, the reliability of buildings and even the safety of people's lives and property for precision instruments, aircraft and important buildings. Therefore, in aviation, aerospace, radar, heavy industry and other fields, bolts that can detect preload are gradually popularized.

China relies on imports to use smart bolts, and the price of a single bolt can reach $300. The cost of bolts is very low. What is expensive is the above sensor and supporting test system. At present, the bolts with pre-tightening force indication on the market mainly include discoloration, rotating head, detection ring and pointer measurement ring. Different from the patch technology used by some peers, the research team of Chengdu Science and Technology Development Center of the Chinese Academy of Sciences has developed a thin film piezoelectric transducer sensor for measuring the pre-tightening force, which uses material technology to "grow" the sensing part directly in situ on the surface of the bolt.

The sensor measures the length change of the screw when the bolt is fastened by emitting ultrasonic wave, and calculates the bolt pre-tightening force by comparing the parameters such as the change of sound velocity under different stress states. High-end equipment such as airplanes and spacecraft often vibrates during operation, which is easy to cause the patch on the bolt to fall off. The sensing part made by the China Institute of Engineering Physics is integrated with the bolt, which can effectively avoid this peeling problem.