INFLUENCE OF PERIODIC PAUSES ON FATIGUE LIFE OF AN AUTOMOBILE HORN BRACKET UNDER VARIABLE AMPLITUDE LOADING
INFLUÊNCIA DE PAUSAS PERIÓDICAS SOBRE A VIDA EM FADIGA DE UM SUPORTE DE BUZINA AUTOMOTIVO SOB CARREGAMENTO DE AMPLITUDE VARIÁVEL
Clayton Mamedes Angelo, Wilson de Simone Carlos, Cláudio Geraldo Schön
Abstract
A metallic horn bracket used in a typical passenger’s car has been tested mounted in the vehicle by using two different approaches: in a proving ground (in the field) and using a road simulator (in a laboratory). The results lead to different durabilities (respectively, failure at 18% and 11% of the complete test). This difference is attributed to the presence of pauses in the field test, which are not present in the road simulator test spectrum. This hypothesis was tested by introducing artificial periodic pauses in bench tests. It is shown that the average fatigue life of the component, which is 170922 cycles in the continuous test, is increased to 239434 cycles by introducing 5 hour pauses each 100000 cycles, to 240848 cycles by using 10 hour pauses, and to 1043743 cycles by using 45 hour pauses. The results are discussed with regard to fatigue testing and durability design.
Keywords
Resumo
Um suporte de buzina metálico empregado em um carro de passageiros típico foi testado como montado na estrutura do veículo usando dois procedimentos: em uma pista de testes (no campo) e em um simulador de estradas (no laboratório). Os resultados mostram diferentes durabilidades (respectivamente falha em 18% e 11% do teste completo). Essa diferença foi atribuída à existência de pausas no teste de campo, que não são presentes no espectro do ensaio usando o simulador de estradas. A hipótese foi testada introduzindo-se pausas artificiais periódicas em testes de bancada. Observa-se que a vida média em fadiga do componente, que é de 170922 ciclos no teste contínuo, aumenta para 239343 ciclos com pausas de 5 horas a cada 100000 ciclos, para 240848 pelo uso de pausas de 10 horas e para 1043743 ciclos usando-se pausas de 45 horas. Os resultados são discutidos em função da relação entre ensaios de fadiga e a confiabilidade estrutural de componentes
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Referências
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