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Nauticus Shaft Fatigue Tool

Nauticus Machinery Knowledge Centre Help library Tools and Calculations Shaft Fatigue Tool

Module Description

The Nauticus Shaft Fatigue module provides advanced fatigue life assessment for propulsion shafts in marine applications. It evaluates the shaft dimensions and load-carrying capacity under various load conditions, ensuring compliance with classification society rules and industry standards.

This module supports:

  • Main Class Fatigue Analysis – Evaluates fatigue strength under free water operational conditions.
  • Ice-Class Fatigue Analysis – Assesses fatigue strength under ice-loading conditions according to the ice class requirements.

Key Features

  • Shaft dimension evaluation based on DNV Rules Pt.4 Ch.4 Sec.1.
  • Calculates allowable torsional vibration stress levels based on low cycle, high cycle and transient fatigue
  • Load-carrying capacity assessment using methodologies defined in DNV Class Guidelines-0038.
  • Detailed sectional input analysis for precise modeling of critical shaft sections and stress hotspots.
  • Notch factor consideration to evaluate stress concentrations due to shaft geometry and surface roughness.
  • Ice load and torque calculation to determine maximum ice torque amplitudes and blade failure load.
  • Total load cycles calculation based on propeller and ice class notation
  • Ice-Class compliance verification using Finnish-Swedish Ice Class Rules, IACS Polar Ice Class Rules and DNV Class Guidelines-0041 to assess shaft strength under ice-induced loads.

Workflow

  1. Model Setup by defining common data, including shaft type, power, speed, material properties and ice class notation.
  2. Ice-class data specification for ice-classed projects, including design torque and blade failure load definitions.
  3. Load case definition by selecting the calculation method and identifying critical shaft section.
  4. Sectional data input including the bending moments, shaft diameters, surface roughness and notch type.
  5. Perform calculation to obtain the main class results (and ice class results if relevant).
  6. Result evaluation and compliance check by comparing results against the criterions.
  7. Optimization by adjusting notch geometries and design parameters to improve fatigue life
  8. Generate compliance reports with stress analysis results and regulatory verifications.