Vehicle Collision Dynamics provides a unified framework and timely collection of up-to-date results on front crash, side crash and car to car crashes. The book is ideal as a reference, with an approach that's simple, clear, and easy to comprehend. As the mathematical and software-based modelling and analysis of vehicle crash scenarios have not been systematically investigated, this is an ideal source for further study. Numerous academic and industry studies have analyzed vehicle safety during physical crash scenarios, thus material responses during crashes serve as one of the most important performance indices for mechanical design problems.
In addition to mathematical methodologies, this book provides thorough coverage of computer simulations, software-based modeling, and an analysis of methods capable of providing more flexibility.
Unifies existing and emerging concepts concerning vehicle crash dynamics
Provides a series of latest results in mathematical-based modeling from front and oblique perspectives
Contains almost everything needed to capture the essence of model development and analysis for vehicle crash
Includes both numerical and simulation results given in each chapter
Presents a comprehensive, up-to-date reference that encourages further study
Structural behavior of the vehicle during the impact
Abstract
In this chapter, after a brief panoramic of the main feature of vehicle structures, focusing on crashworthiness, the phenomenological aspects of the crash are presented. The acceleration/time, velocity/time, and deformation/time curves acquired during a generic crash test are reported. The forceâdeformation characteristic curves well represent vehicle crash behavior. The main parameters influencing the forceâdeformation curves are also discussed, as the test speed, the crash configuration (offset, underride, etc.).
1.1 Crashworthiness structures and phenomenological aspects of the impact
The bodywork must offer the necessary resistance to static and dynamic stresses induced during the motion of the vehicle, to ensure an adequate flexural and torsional stiffness and to protect the occupants of the car in case of an accident.
The type of bodywork used by most of the vehicles in production is the monocoque (uni-body) of molded steel sheet (Fenton, 1999; Heisler, 2002). The bearing shell is constituted by a spatial structure composed of more subtle elements of complex shape, joined together through spot welding. These elements contribute through their stiffness to the structural behavior of the body. The floor pan is constituted by the longitudinal members, the plane sheets, the crosspieces, the wheel arches, and the eventual transmission tunnel. The side pillars and the upper pavilion are fixed on the floor pan; the pillars are named A, B, and C pillars, which define the shape of the bodywork.
In the event of a frontal or lateral collision, different structures of the monocoque are involved, as shown in Fig. 1.1.
In some vehicles, typically commercial vehicles, off-road vehicles, and some Sport Utility Vehicles (SUV) and Multi-Purpose Vehicles (MPVs), the body is made with a separate chassis, realized through longitudinal members (body on frame or ladder chassis). This type of chassis is constituted by a substantially planar structure, composed of two longitudinal elements (spars), connected by several transverse elements (crossbars), which is entrusted with the task of providing resistance to lateral forces and to conferring torsional stiffness (see Fig. 1.2).
Recently, the construction of the body concerning the âspace frameâ (SF) geometry has been widespread, particularly indicated to be made of aluminum alloys. The SF is formed by a reticular structure consisting of a network of elements connected at the ends through rigid joints, typically made by casting, to form spatial geometries. Support functions of both the power train and chassis components are assigned to this spatial cage. Moreover, structural tasks to confer adequate stiffness to the vehicle and protect passengers in case of an accident are assigned to the spatial cage (Fig. 1.3).
The core idea of crashworthiness structure design is to preset a crumple zone, which can absorb the kinetic energy of vehicles during crashes, possibly lowering the acceleration. In a frontal crash, for example, the stiffness of the front structure determines the acceleration pulse during a crash. This pulse should have a specific shape, ...