Tactical operator guidance to mitigate naval vessel structural fatigue damage

Abstract

A unique application of spectral fatigue analysis evaluates tactical operator guidance intended to mitigate fatigue crack initiation. Specifically, assessments examine the effects of reducing speed or changing heading away from head seas. The evaluation aims to determine whether fatigue damage accumulation may be mitigated by advising operators to change speed or heading. Using long-term operational history allows a focus on conditions with significant lifetime contributions to fatigue damage accumulation. Also, additional seaway exposure from changing speed or heading is considered for fixed-destination operations. Ship speed reduction effects are mixed. When in a seaway for a fixed duration, reducing speed usually lowers fatigue damage accumulation. Conversely, sailing slower increases fatigue damage accumulation while transiting to a fixed destination because of greater seaway exposure. Regardless of operation type, shifting heading farther from head seas tends to reduce fatigue damage accumulation. Tactical guidance can effectively mitigate fatigue damage, but the operation type requires consideration.