Proactive regulation of axial crushing behavior of thin-walled circular tube by gradient grooves

摘要

The progressive buckling behavior of a gradient grooved tube (GGT) designed for high temperature gas cooled reactor (HTR) is systematically studied in this paper. Based on the plastic hinge formation process, a sectionalized theoretical model is established to predict the quadratic upward trend of crushing force of GGT. The ordered and stable energy absorbing process of GGT is examined by low-speed axial impact using drop hammer test machine. The effect of proactive regulation parameters, including non dimensional groove width W/(h(0)+h), groove depth h(0)/h and half wavelength (H+W-h)/root Dh on buckling modes and force-displacement curve is determined by experiments and FE simulation. The non-dimensional groove width W/(h+h(0)) is determined as pi/2 according to the geometry coordination of bending grooves. The non-dimensional groove depth h(0)/h influences local buckling behavior and the critical value 0.6 for regular bending has been determined by numerical simulation. The quadratic trend force-displacement curves of GGT can be actively controlled by (H+W-h)/root Dh within a certain range less than 1.2. Free-fall impact experiments show that GGT has a better stability than perfect tube when used as an energy absorber to protect the graphite in HTR from slender control rod impact. (C) 2016 Elsevier Ltd. All rights reserved.