Jerry S Ogden, PhD, PE
Over 25 years of industry experience in Civil, Mechanical and Traffic Engineering, specializing in Engineering Forensics and Collision Analysis. Fellow, Diplomate and a member of the Board of Directors for the National Academy of Forensic Engineers, Diplomate of the International Board of Forensic Engineering Sciences, Licensed Professional Engineer in multiple jurisdictions.
Phone: (303) 795-1515
Address: PO Box 621519
Littleton, Colorado 80162
Phone: (303) 795-1515
Address: PO Box 621519
Littleton, Colorado 80162
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This paper presents the application of the Generalized Deformation and Total Velocity Change Analysis to real-world collision events (G-DaTADeltaV System of Equations) as developed by this author. The focus of this paper addresses the relative precision and accuracy of the G-DaTADeltaV System of Equations for determining the total velocity change for oblique and/or offset vehicle-to-vehicle collisions involving light trucks and sport utility vehicles, which are largely under-represented with modern vehicle A and B stiffness values for side and rear surfaces. The previous paper presented by this author to the Academy addressed the relative accuracy and precision of the G-DaTADeltaV System of Equations as they relate to a first validation using the RICSAC-staged collision database1 As a secondary and more comprehensive validation process, the G-DaTADeltaV System of Equations will be applied to real-world collision data obtained through the National Automotive Sampling System (NASS), which provides the National Highway Traffic Safety Administration (NHTSA) with a comprehensive compilation of real-world collision events representing a broad-based collection of collision configurations from across the country. This data represents a reusable source of information that was collected using standardized field techniques implemented by NASS-trained field technicians. Through using a "core set of crash data components," NASS has demonstrated its utility and applicability to a vast array of statistical and analytical studies regarding traffic safety and vehicle collision dynamics.
The primary goal of this research is to develop an accurate, reliable and broadly applicable deformation analysis method that requires the structural stiffness coefficients for only one collision involved vehicle. The developed methodology expands the application of deformation analysis to include unconventional vehicles and other objects and surfaces not supported by the current structural stiffness coefficient database. The G-DaTAV™ System of Equations incorporates linear and rotational effects, as well as impact restitution resulting from conservative forces acting during a given collision impulse. Additionally, the G-DaTAV™ System of Equations accounts for tire-ground forces and inter-vehicular friction, non-conservative force contributions acting on the collision system that are commonly present during offset and oblique non-central collision configurations.
Correlation and descriptive statistics, as well as the raw analysis results, indicate a highly reliable and significantly improved degree of precision and accuracy achieved through the application of the G-DaTADeltaV™ System of Equations when determining vehicular total velocity changes for oblique and offset non-central impacts.
marks, speeds from scrapes or gouges, speed from rider ejection, speed from linear momentum, or
sometimes speed from witness observations. Oftentimes, the data necessary for analysis is either misunderstood
or misinterpreted. This paper tests the applicability of using rotational mechanics and specific
models for motorcycle front fork deformation and vehicle deformation when determining motorcycle
impact velocity. Additionally, the results of these methods are statistically tested for significance and
reliability against independent motorcycle impact test data. NAFE Journal June 2012
Conference Presentations
This paper presents the application of the Generalized Deformation and Total Velocity Change Analysis to real-world collision events (G-DaTADeltaV System of Equations) as developed by this author. The focus of this paper addresses the relative precision and accuracy of the G-DaTADeltaV System of Equations for determining the total velocity change for oblique and/or offset vehicle-to-vehicle collisions involving light trucks and sport utility vehicles, which are largely under-represented with modern vehicle A and B stiffness values for side and rear surfaces. The previous paper presented by this author to the Academy addressed the relative accuracy and precision of the G-DaTADeltaV System of Equations as they relate to a first validation using the RICSAC-staged collision database1 As a secondary and more comprehensive validation process, the G-DaTADeltaV System of Equations will be applied to real-world collision data obtained through the National Automotive Sampling System (NASS), which provides the National Highway Traffic Safety Administration (NHTSA) with a comprehensive compilation of real-world collision events representing a broad-based collection of collision configurations from across the country. This data represents a reusable source of information that was collected using standardized field techniques implemented by NASS-trained field technicians. Through using a "core set of crash data components," NASS has demonstrated its utility and applicability to a vast array of statistical and analytical studies regarding traffic safety and vehicle collision dynamics.
The primary goal of this research is to develop an accurate, reliable and broadly applicable deformation analysis method that requires the structural stiffness coefficients for only one collision involved vehicle. The developed methodology expands the application of deformation analysis to include unconventional vehicles and other objects and surfaces not supported by the current structural stiffness coefficient database. The G-DaTAV™ System of Equations incorporates linear and rotational effects, as well as impact restitution resulting from conservative forces acting during a given collision impulse. Additionally, the G-DaTAV™ System of Equations accounts for tire-ground forces and inter-vehicular friction, non-conservative force contributions acting on the collision system that are commonly present during offset and oblique non-central collision configurations.
Correlation and descriptive statistics, as well as the raw analysis results, indicate a highly reliable and significantly improved degree of precision and accuracy achieved through the application of the G-DaTADeltaV™ System of Equations when determining vehicular total velocity changes for oblique and offset non-central impacts.
marks, speeds from scrapes or gouges, speed from rider ejection, speed from linear momentum, or
sometimes speed from witness observations. Oftentimes, the data necessary for analysis is either misunderstood
or misinterpreted. This paper tests the applicability of using rotational mechanics and specific
models for motorcycle front fork deformation and vehicle deformation when determining motorcycle
impact velocity. Additionally, the results of these methods are statistically tested for significance and
reliability against independent motorcycle impact test data. NAFE Journal June 2012