Study on the 30 MN force calibration system in tension with failure protection

Abstract

The maximum risk in the calibration of tension force in the meganewton range comes from failure of the transducer. The impact caused either by the yield fracture or by the unforeseen brittle fracture can lead personal injury or equipment failure. In this work the deformation and energy effect of the 30 MN transducer upon fracture was evaluated. A new tension force calibration system with a failure protection function witch is consisted of micro-displacement monitoring devices and thin shell structure was built. The thin shell structure is made of stainless steel with multiple arrays honeycomb bulges that will produce large deformation to absorb energy upon impact. The dual ball nuts structure conforming to the Annex A.4 of ISO 376 requirements is applicable for this system, and the coaxial can be guaranteed in calibration. Measurements were performed at the 60 MN build-up machine (BM) in FJIM. It is shown that the system has sufficient stiffness with a 30 MN force, and the participation of the tension system did not influence the measurements in BM. Displacement at 0.02 mm level can be monitored in real time and deformation curve to warn yield failure proactively, and the passive protection structure absorbed energy in an unexpected brittle fracture at nearly 18 MN and protected the BM and personnel safety.