How can internal stress concentration in profile cross-section design be minimized as much as possible?

① When unequal wall thicknesses are unavoidable, a gradual transition should be provided at the junctions of different wall thicknesses to avoid abrupt changes in thickness, as shown in the figure;  

② Wall thickness should be designed as thin as possible while still meeting strength requirements;  

③Due to functional and mechanical performance requirements of the cross-section, the design thickness of internal ribs and reinforcing ribs is generally recommended to be 30% to 50% less than that of the outer wall. This helps prevent relatively low heat transfer efficiency and significant differences in cooling efficiency—caused by the fact that internal ribs and reinforcing ribs are often located within cavities—resulting in high internal stresses.