1. Glass Fracture

2. What causes glass to break?
Force – such as a bullet, vehicle or rock
fractures will help determine the side of impact
Heat
Varies because the fractures are wave-shaped and irregular; no ridge lines

3. Glass Vocabulary
Side of compression – Compression means squeezed; this is the same side the force is exerted on
Side of tension – tension is where something is stretched; this is the side of glass opposite the force
Radial fractures – spider web from point of impact.
Concentric fractures – broken circles formed around the point of impact

4. Radial and Concentric Fractures
This is the side opposite of the force. You can see how the glass is stretched. This stretching causes the concentric fractures.
Force exerted from this side. You can see that the glass is compressed on the side of the force.

5. Formation of Fractures
Radial fractures occur first on side OPPOSITE the force.
Concentric fractures occur second on SAME side as force.

6. ROT CSC Radial Opposite Tension Concentric Same Compression Which side
(fracture) (impact side) (stress)
Concentric Same Compression
Which side
Breaks FIRST?

7. Difference between ridge lines on radial and concentric fractures
In radial fractures, you’ll see the perpendicular lines on the side opposite the force or point of impact
In concentric fractures, you’ll see the perpendicular lines on the same side of the force or point of impact
Ridge lines