Debug Render

Blast Actor/BlastMeshComponent comes with debug render options in editor in order to see what is going on under the hood. Look for Blast Debug Render Mode setting under Blast/Advanced section. It allows to draw:

Support Graph

Stress Graph

*Note: Stress graphs are visible in PIE.

Chunk Centroids

Consider using wireframe mode (F1) together with it.

You can also view collision shapes by toggling Show/Collision in the usual UE4 viewport menu on the top.