Forensic Biomechanics

The principle factor in the bone's resistance to fracture is its toughness, in other words, the bone's ability to resist crack propagation at multiple hierarchical levels.

“The principle factor in the bone’s resistance to fracture is its toughness, in other words, the bone’s ability to resist crack propagation at multiple hierarchical levels [6,12].”

Such injuries can cause severe bone fragmentation as a result of the instant accumulation and release of massive levels of energy.

“Such injuries can cause severe bone fragmentation as a result of the instant accumulation and release of massive levels of energy [6].”

Bone fracture patterns are attributable to the magnitude and rate of loading force, which determine the amount and rapidity of stress applied to bone before it deforms or fractures.

“In particular, bone fracture patterns are attributable to the magnitude and rate of loading force, which determine the amount and rapidity of stress applied to bone before it deforms or fractures [6].”

Bones will resist, begin to fracture, and eventually fail in accordance with the stress-strain curve.

“Bones will resist, begin to fracture, and eventually fail in accordance with the stress–strain curve [6].”

In GST, bone behaves as a brittle material when fracturing because the rate of energy transfer is too high for viscoelastic compensation.

“In GST, bone behaves as brittle material when fracturing due to the rate of energy transfer being too high for viscoelastic compensation [6].”

Unlike BFT, where elastic deformation is followed by plastic deformation and eventual bone failure, viscoelastic bone in response to the high velocity of bullets acts as a brittle material and fails upon contact.

“However, unlike BFT, where elastic deformation is followed by plastic deformation and eventual bone failure; viscoelastic bone in response to the high velocity of bullets acts as a brittle material and fails upon contact [6,8].”

The exact biomechanics behind ballistic bone trauma remain controversial as it is difficult to apply the fundamental laws of mechanics to such a transient event.

“The exact biomechanics behind ballistic bone trauma remain controversial as it is difficult to apply the fundamental laws of mechanics to such a transient event [6].”

In BFT, bone behaves as a ductile material and is elastic and flexible, allowing more energy to be transferred to the stretch mechanism, resulting in less damage compared to GST samples.

“In BFT, bone behaves as a ductile material and is elastic and flexible allowing for more energy to be transferred to the stretch mechanism, resulting in less damage compared to the GST samples [6].”

OD type 4 is an indicator of bone behaving as a brittle material, as expected with the rapid loading rate in GST cases and with the dry nature of BFT_dry experimental.

“Perhaps, OD type 4 is therefore an indicator of bone behaving as a brittle material as is expected with the rapid loading rate in the GST cases and with the dry nature of BFT_dry experimental, preventing the bone from withstanding as much strain or elastic deformation [6].”