Thermo-mechanical fatigue design of automotive heat exchangers

Abstract

Automotive heat exchangers are manufactured using brazed thin aluminium tubes and are submitted to pressure pulses, thermal shocks and corrosion. Thermal shocks induce low cycle thermo-mechanical fatigue that leads to failure after several thousand cycles. We propose a thermo-mechanical fatigue design approach for automotive heat exchangers based on the experimental identification of the thermal history during the thermal shock by infrared thermography, the identification of the cyclic elasto-plastic behaviour of the brazed aluminium tubes and the development of a multiaxial lifetime criteria. A finite element simulation of the cyclic thermo-mechanical response in the critical area of the heat exchanger and the use of a multiaxial energy based lifetime criteria lead to the prediction of the heat exchanger’s life.