Under which conditions do slip critical joints perform exceptionally well?

Slip critical joints are designed to transfer loads through friction between the faying (touching) surfaces of the connected elements, rather than relying on the shear strength of the bolts themselves. For these joints to perform exceptionally well, the surfaces must be clean and adequately prepared, which allows for maximum frictional resistance.

When the faying surfaces are clean of any contaminants like dirt, oil, or rust, and are properly prepared—often including processes such as grinding or blasting to achieve the appropriate roughness—they can achieve a higher clamping force, leading to an effective transfer of loads without slip occurring. This preparation enhances the friction that is critical to the joint's performance, particularly under dynamic loads where any slip could compromise structural integrity.

While rough surfaces can also contribute positively, the most critical factor is cleanliness and adequate preparation, as this ensures that the surfaces can engage properly and maintain the needed friction over time.