Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Similarity-Based Models for Testing Vehicle Roofs Against Crushing During Impact Events
Submission Author:
João Marcos Hilário Júnior , DF , Brazil
Co-Authors:
João Marcos Hilário Júnior, Paulo Guilherme Marques Flavio, Alessandro Oliveira, RITA DE SILVA
Presenter: João Marcos Hilário Júnior
doi://10.26678/ABCM.COBEM2021.COB2021-1696
Abstract
A vehicle rollover is one type of automotive accident that causes about 25% of deaths in crashes of cars and 59% in SUVs. The excessive crushing of the vehicle’s roof is the reason that leads these accidents to cause severe and fatal injuries caused by excessive intrusion into the occupant’s compartment (safety cell). One approach to mitigate such a structural failure is to increase the structural performance of the vehicle’s roof. However, to investigate the structural strength of vehicular roofs, we can carry out experimental tests or numerical simulations. This performance can be analyzed by a complementary test proposed by the international standard FMVSS 216a - Roof Crush Resistance Test that evaluates rollover crashworthiness for passenger vehicles. This quasi-static test helps to determine the force required to push a metal plate into the roof at a constant velocity rate. It requires a reaction force equal to 3 times the vehicle's weight to be reached within 5 inches (127 mm) of plate displacement. The present work carried out finite element numerical simulations of two vehicular roofs applying some of the boundary conditions previewed in such an experimental test. In the numerical analysis, only the roof was tested, contrary to the standard that considers the whole vehicle in the test platform. One vehicle roof was designed based on the Similitude Theory using the Buckingham π theorem and, it was called the ‘Model.’ The other, known as ‘Prototype,’ had the actual dimensions of the SUV Ford Explorer 2003. The samples were made in metallic tubes obtained from the regular stock of commercial product suppliers. The structural layout is a cage. The Model was built on a scale of 1:0.453 considering the available commercial thicknesses of tubes; it was the restrictive factor. The main objective of this work was to evaluate the numerical response of the Prototype through the Model’s behavior under crushing phenomena. The structural response of interest was the force x displacement in column A. The FE analysis carried out on the Model and Prototype demonstrates geometric and kinematic similarities between them, as previewed in the π values. The findings show that it is possible to carry out roof crush testing in the reduced Model and predict the Prototypes' structural behavior. Such an approach reduces costs inherent to the manufacturing process and operational difficulties related to the vehicle roof's physical installation.
Keywords
similarity theory, vehicle roof, Finite Element Method, FMVSS 216a, roof crush
