The Physics Eliminates the Vandalism

A window failure produced an unusual pattern of very long thin curved glass fragments. A simple virtually intuitive physics experiment explains the cause of the failure. If one were to grip a sheet of paper on either edge with the right and left hands and pull outward the paper will rip or fail from top to bottom or vice versa. Two pieces of the original sheet result, the failure line being at right angles to the direction of the applied force. (ie the force was horizontally outward and the tear was vertically up or down)

The glass fragments being virtually all long and thin resulted from the application of force from the edges of the glass pane. Pushing the edges inward forced the glass pane to bulge out of the plane of the sheet and when the glass failed it broke into long thin curved shards.

Although the suggestion had been made that the destruction of the glass had been vandalism, the failure mode and additional investigation demonstrated a substantial compression deformation of the metal mounting frame. Metals are noted for their ductility or flexibility but glass has virtually none.