The valves of an internal combustion engine play an essential role in the automobiles and their surroundings significantly affect their thermo-mechanical behavior. The work aims to assess numerically the effect of the real thermo-mechanical boundary conditions on the valves by considering the actual complex surrounding. For this purpose, we have subdivided the valve into seven adequate zones. We have evaluated the average values of the transient heat transfer coefficient, the adiabatic wall temperature and the mechanical load at each subdivision are during the opening and the closing periods. A transient Finite Element Model under ANSYS APDL software is developed and simulations are carried out until reaching the steady state. The temperature distribution and the thermal stresses at each valve position is obtained and then analyzed. The main findings show that the stress intensity distribution is developed in the zones labelled stem guide port and seat local of large temperature gradients, which causes high thermal stresses responsible of cracks or thermal fatigue damage. In addition, knowing the temperature map, the thermal gradient and stress under actual conditions will surely help manufacturers to better design exhaust valve, avoid early failure and enhance the durability of valves.

内燃机的气门在汽车中起着至关重要的作用，其周围环境会显着影响它们的热机械性能。该工作旨在通过考虑实际复杂的环境，以数值方式评估真实热机械边界条件对阀门的影响。为此，我们将阀门细分为七个足够的区域。我们已经评估了每个细分的瞬态传热系数、绝热壁温和机械载荷在开启和关闭期间的平均值。建立ANSYS APDL软件下的瞬态有限元模型并进行仿真直至达到稳态。获得并分析每个阀门位置的温度分布和热应力。主要发现表明，应力强度分布在标记为阀杆导向端口和大温度梯度的阀座局部区域中发展，这会导致导致裂纹或热疲劳损坏的高热应力。此外，了解温度图、实际条件下的热梯度和应力，必将有助于制造商更好地设计排气阀，避免早期失效并提高阀门的耐用性。