Forensic Analysis Of Low Speed Vehicle Collisions

Abstract

A Low Speed Collision Is Defined, For The Purpose Of This Paper, As A Collision Between Two Vehicles That Produces No Permanent Damage To The Body Of The Vehicle Except To The Bumper System. The Vehicles Are Equipped With Energy Absorbing Bumpers That Are Rated To A Particular Speed. The Collisions Are, For All Intents And Purposes, In-Line In Nature (Collinear) And Without Post-Impact Rotation. This Definition, While Quite Specific, Covers A Large Number Of Collisions. They Are The Typical Stop Sign, Waiting In Traffic, Parking Lot Type Crash. In The Following Sections I Will Examine How These Vehicles Interact And Respond To Such Collisions By Applying Newtons Laws And The Data From Vehicle Crash Tests. Presented Is Methodology For Reconstructing The Pre-Impact And Post-Impact Speed Of Such Collisions Using The Following Protocol: 1. Compute The Kinetic Energy Dissipated In The Collision From The Characteristics Of The Vehicles And Their Bumpers As Revealed In Crash Tests. 2. Use Conservation Of Energy And Damage Relationships To Determine The Pre-Collision Kinetic Energy And Closing Speed Of The Two-Vehicle System. 3. Use Conservation Of Linear Momentum To Calculate The Post-Collision Speed And Delta-V Of The Two Vehicles. This Method Uses The Strict Application Of Newtons Laws And Treats Both Vehicles As A System.