International Research Journal of Engineering and Technology (IRJET) Volume: 12 Issue: 07 | Jul 2025
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e-ISSN: 2395-0056 p-ISSN: 2395-0072
Collision pulse modeling: Closed form solutions for sinusoids exponentiated to integer powers Jai Singh1 1Biomechanical Engineering Analysis & Research, Inc., Thousand Oaks, California, USA ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - The subject work extends the mathematical
mortality risk for the occupants of the collision partner [24]. The scientific literature contains numerous studies that have focused on the relationship between vehicular collision partner crash pulse metrics and the potential for occupant injury [8, 25-28].
framework for the well-established use of half period and quarter period sine and sine squared functions for modeling collision pulses within the contextual fields of accident reconstruction, occupant kinematics and biomechanical engineering. The topical focus of the material presented herein is the derivation of the kinematic equations (i.e. acceleration, velocity and displacement) for the cases in which either a sine or cosine function, exponentiated to an arbitrary, positive, integer value, is used as the base function for modeling a segment of the underlying acceleration. The closed form analytic solutions presented also account for non-zero valued initial acceleration offsets and for the use of partial full period responses beyond, but inclusive of, the quarter and half period responses.
Generally, the event pulses associated with actual collisions contain multiple local extrema and therefore are modeled in only an approximate sense when a single analytic closed-form modeling equation is used. The scientific literate contains a number of studies that have evaluated the utility of exactly such an approach, using simple functions, for the kinematic response due to collision loading [9, 13, 26, 28-31]. One function that has been commonly used is the sine function, raised to either the first power or raised to the second power (i.e. haversine function). If x denotes the operand of the sine or haversine function, then both functions are zero valued when x = n, where n is an integer. Both functions have peak magnitude when x = 0.5n (again, where n is an integer, but excluding zero). The sign of the peak magnitude alternates between and any successive values of n and n + 1. Both functions are oscillatory. The period of the sinusoidal waveform, T, represents the time for one full cycle of the sinusoid. The period is related to the ordinary frequency, f (measured in units of Hz, i.e. cycles per second), by T = 1/f, and to the circular frequency, (measured in units of Hz), of the sinusoid, by T = 2/. The haversine function rectifies the magnitude of the sinusoid. For modeling the entirety of an event pulse, the half period response is typically used. Figure 1 depicts both functions shown over four periods and also over one half of a period.
Key Words: Collision pulse modelling, Accelerationtime history analytic modelling, Trigonometric modelling, Sine, Cosine
1. INTRODUCTION The synonymous terms crash pulse and collision pulse, as either explicitly defined or implicitly used in the scientific literature, refer to the shape and characteristics of the acceleration or deceleration (referred herein as acceleration) experienced by an object or structure when subjected to an impact [1-7]. The characterization of the shape of the acceleration-time history along with its other characteristics can be applied to any event in which an object or structure incurs an acceleration due to the event. The term event pulse is thusly adopted to account for this extension. Contextually, the literature contains evaluations of the event pulses for motor vehicles subjected to collisions [5-7, 8-12], motor vehicle seats [13], motor vehicle occupants [14-16] and coupled analyses involving multiple structures [6, 17-23]. One of the determinable characteristics of any event pulse is the area encompassed between the abscissa and the acceleration response curve. Mathematically, this area is the first time integral of the acceleration and represents the velocity change (delta-v or v) incurred by the object or structure due to the event. Within the context of motor vehicle collisions, the velocity change incurred by a vehicular collision partner, due to an impact, represents the most important factor when it comes to predicting the
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Figure1: Four period response for a sine wave (blue) and haversine wave (orange) shown on the left and the half period responses shown on the right. The half period response of either the sine function or haversine function has certain desirable characteristics when it comes to modeling the entirety of an event pulse.
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