Radial Crack
Definition
A crack that runs outward from the point of impact, like spokes of a wheel. The 3R rule applies: Radial cracks have Ridges on the Reverse side of the force.
- Direction
- Outward from impact point
- Related rule
- 3R rule (Radial-Ridges-Reverse)
- Ridge location
- Reverse side of the force
Common questions
How does the 3R rule help determine the direction a bullet travelled through glass?+
By examining the ridge lines on a radial crack under a hand lens or stereo microscope, an examiner can tell which face is the reverse side relative to the applied force, indicating the direction the impacting object came from.
How can radial cracks be distinguished from concentric cracks at a glance?+
Radial cracks radiate outward from the impact point like spokes, while concentric cracks form roughly circular rings around it; they typically form in sequence, with radial cracks appearing first.
Related terms
- Borosilicate Glass
- Heat-resistant glass with about 80 percent SiO2 and 13 percent B2O3 (boric oxide). Low thermal expansion. Used in cookware (Borosil, Pyrex) and...
- Concentric Crack
- A crack that runs in roughly circular arcs around the point of impact, joining radial cracks. The 4C rule applies: Concentric cracks...
- Float (Pilkington) Glass
- Sheet glass manufactured on a bath of molten tin. The tin-contact face fluoresces under short-wave UV, which lets the analyst orient a...
- Laminated Glass
- Two glass sheets bonded with a polyvinyl butyral (PVB) interlayer. Cracks but does not shatter. Standard for windshields and bank counters. The...
- Soda-Lime Glass
- The commonest glass family. About 72 percent SiO2, 14 percent Na2O (from soda ash) and 10 percent CaO (from limestone), with small...
- Tempered Glass
- Glass heat-treated to introduce compressive surface stresses and tensile core stresses, producing a material four to five times stronger than annealed glass...
- Wallner Lines and Hackle Marks
- Wavy curved lines (Wallner) and step-like ridges (hackle) on a fracture surface that record the direction the crack front was moving. Used...