What is the primary purpose of split sleeve cold expansion in aerospace applications?

The primary purpose of split sleeve cold expansion in aerospace applications is to retard the growth of cracks in fatigue critical areas. This process involves the use of a split sleeve that is placed over a drilled hole in a metal component. By expanding the hole through mechanical means, compressive residual stresses are introduced into the surrounding material.

These residual stresses play a crucial role in enhancing the material's fatigue resistance. When a component is subjected to cyclic loading, which is common in aerospace environments, the presence of compressive stresses helps to inhibit crack propagation. This process effectively improves the longevity and reliability of critical structures that are subject to fatigue failures, such as wing structures, fuselage components, and other load-bearing elements.

The other options pertain to different material properties and enhancements, but they do not directly relate to the primary mechanical advantage offered by split sleeve cold expansion. Enhancing thermal conductivity, improving corrosion resistance, or facilitating hydraulic fluid flow are not the main goals of this specific method, making them less relevant in the context of fatigue management in aerospace applications.