Crushable Spacer Geometry for Predictable Bolted Joint Failure

The patent applies preliminary action by incorporating weakening features (such as notches, grooves, or reduced thickness sections) into the spacer wall before the spacer is installed. These pre-defined weak points are strategically placed to ensure that when excessive load occurs, the spacer will fail at these predetermined locations rather than undergoing extensive elastic deflection and yielding. This pre-prepared failure path eliminates the inconsistent failure timing observed in uniform spacers, as all spacers with identical weakening features will fail at approximately the same load level.

The patent applies parameter changes by modifying the wall thickness parameter of the spacer. Instead of using uniform wall thickness throughout, the spacer incorporates sections with reduced thickness (t1) compared to the main body thickness (t2). This parameter variation creates controlled weak points that significantly reduce the load required to initiate failure at those specific locations, thereby shortening the deflection period before failure and ensuring consistent failure timing across multiple spacers subjected to overload.

The patent applies preliminary action by pre-defining failure locations through weakening features in the spacer wall. This ensures that under excessive load, the spacer will fail in a controlled manner at these predetermined weak points rather than transferring unpredictable extreme forces to surrounding components. The weakening features act as sacrificial elements that absorb the excessive energy, protecting the main structural components from unpredictable failure modes.

The patent applies the blessing in disguise principle by intentionally creating weak points (harmful features) in the spacer wall that reduce its overall strength. However, this apparent weakness becomes beneficial under excessive load conditions, as these weak points ensure controlled, predictable failure that protects surrounding components. The harmful feature (reduced wall thickness) transforms into a protective mechanism that prevents more serious damage to critical engine components.