ABSTRACT
Reconstructionists use crash test results to evaluate the nature and severity of crashes experienced by vehicles involved in field (that is, real-world) accidents. It is important, therefore, to have an understanding of how crash tests are conducted, what data are collected and why, and how to interpret the results. Chapter 12 provides basic information in that regard. It introduces the concept of the crush zone that deliberately deforms and absorbs energy, while other parts of the vehicle remain as little deformed as possible. These regions vary according to the type of collision (front as compared to rear, for example). Such considerations guide the placement of accelerometers and other transducers (that may measure force, velocity, and displacement, for example). It is very important to be cognizant of sign conventions and coordinate systems, particularly when are two crash partners. Misunderstandings may lead to bizarre interpretations.
Data from crash tests by the National Highway Traffic Safety Administration (NHTSA), being publicly funded, are in the public domain. Chapter 12 discusses how to find and access crash test reports and crash test data through the NHTSA crash test database. The filtering that the NHTSA utilizes in the data plots presented in its reports is described. The discussion builds on material presented in Chapter 11.
It is generally the case that crash test data plots are no longer included in NHTSA reports. Instead, the user must download digitized data, which are not filtered. For proper analysis, interpretation, and description, the data must be filtered by the user. Chapter 12 presents a description of how the NHTSA filter algorithm works, along with the BASIC source code for the NHTSA filter routine. However, the NHTSA has produced a suite of computer programs called the Signal Analysis Software. These are very useful, contain various classes of second-order Butterworth filters, and may be downloaded and used free of cost.
