Multi-physics modeling of LED-based luminaires under temperature and humidity environment

The purpose of this work is to conduct the multi-physics simulation analysis of LED-based luminaires under certain temperature and humidity environment, and to find out the vulnerable spot of the luminaire. The coupled modeling of LED luminaire during step stress accelerated test (SSAT) is simulated by ANSYS. Five types of modeling, i.e. thermal and thermo-mechanical modeling, moisture diffusion and hygro-mechanical modeling, and thermo-mechanical-moisture modeling, at various temperature level of temperature 45°C, 85°C and 95°C, and 60% relative humidity are performed by multi-physics approach which using finite element method combined with additional user subroutines. Then, the effect of thermal expansion, hygroscopic swelling and delamination on the luminaire is predicted. Finally, SSAT is carried out to accelerate aging of LED bulbs, and the failure modes are found out. It is shown that the simulation results agree with vulnerable spot well from the test, which indicates that the multi-physics approach can be used for simulating the condition of LED-based luminaire in real and predicting the failure modes.