1.      Experimental and numerical study of thin-walled cylinder energy absorber for the protection of graphite in nuclear reactor

In this study, several crashworthiness parameters of a circular, thin tube energy-absorbing structure, which is used in a high-temperature, gas-cooled reactor (HTR), are studied experimentally and numerically at various tube thicknesses, temperatures and impact velocities. The average crushing force is fundamentally dependent on strain hardening, strain rate hardening, and, particularly, temperature softening of the material. The peak forces during buckling are significantly affected by the localstrain rate in the material and exhibit a decreasing trend in sequentially formed folds. Additionally, the stress concentration at the edge of the backplate graphite contact surface is evaluated in detail to ensure the structural security of the energy absorber.

Fig. 1Comparison of buckling modes and shapes of the plastic hinge. (a) Buckling modes, (b) 1st fold, (c) 2nd fold, (d) 3rd fold.

Fig. 2Transient crushing force-displacement curve