Eventos Anais de eventos
CONEM 2022
XI Congresso Nacional de Engenharia Mecânica - CONEM 2022
EFEITO DA DENSIDADE DE MALHA NA ENERGIA DE HOURGLASS EM SIMULAÇÕES MULTI-IMPACTO
Submission Author:
Pedro Gabriel Oliveira da Silva dos Santos , DF
Co-Authors:
Pedro Gabriel Oliveira da Silva dos Santos, Klyssmann Henrique Ferreira de Oliveira, RITA DE SILVA, Alessandro Oliveira
Presenter: Pedro Gabriel Oliveira da Silva dos Santos
doi://10.26678/ABCM.CONEM2022.CON22-0657
Abstract
Given the increase in the use of vehicle armor in Brazil, it urges the development of reliable numerical models that can reproduce the impact phenomenon. The investigation of the protection efficiency is justified due to the severe consequences that a failure can cause. In Brazil, vehicle shielding is regulated by NBR 15000 and NEB E-316. The first provides that the armor must withstand five impacts at the highest level of protection allowed to civilians. Thus, the present work uses the finite element method to numerically examine the effect of the change in mesh density on the hourglass energy when simulating the multi-impact of projectiles on a rectangular metal plate. Hourglass energy consists of energy added to numerical calculations to prevent elements from deforming in a way incompatible with the actual phenomenon. It represents a way to evaluate the quality of the numerical study. The material selected for the projectiles was brass, and 304L steel for the plate, mainly applied for this purpose. In this study, projectiles were characterized as rigid bodies. Five different mesh densities were simulated, varying the size of the elements between 5 mm and 0.4 mm on the plate. The initial velocity of each projectile was 426 m/s, and the plate was fixed in its four lateral faces. The numerical analyzes used the explicit integration methodology and were performed using Ansys – Explicit Dynamics, version 18.1. As a result, the residual velocity of each of the projectiles, the maximum displacement of the plate, and the history of the system's kinetic, internal, and hourglass energy were obtained as a function of the number of simulations cycles. At the end of the five simulations, the ratio between the hourglass energy and the internal energy was reduced from 97.05% to 17.76%.
Keywords
densidade de malha, energia de hourglass, impacto balístico, proteção balística
