Experiment Study on Collision of Graphite Dowel-Brick Structures

Graphite bricks have important applications in high temperature gas-cooled reactors (HTGRs), the core of HTGR is a pile-up of graphite bricks. So the vibrations and collisions between graphite bricks caused by external excitation have an important influence on structural stability of the core. The locations of bricks are fixed by various kinds of keys and dowels. The collision experiment, with tracks and small railcars as experimental devices and measurement system using optical method, was aimed at studying non-central collisions between two bricks. The passive one of the two bricks was equipped with a key or a dowel. Experiment’s results revealed how the coefficient of restitution and the contact time would change within the range of velocities of the active specimen. It was showed that the contact time would increase with the rise of initial velocity while the coefficient of restitution would rise up firstly and then decrease later in the same process. Besides, qualitative influence caused by different sizes of keys and dowels was briefly discussed, and material properties of graphite was not the dominate factor in the collision of dowel-brick structures experiment, while the velocity of active specimen just before collision and the fact that the collision is non-central have more significant effects on the collision results.