Crankshaft design and analysis - Nauticus Machinery Crankshaft Fatigue

Crankshaft analysis software for calculations of fatigue

Crankshaft design software

DNV has approved crankshaft design for decades. We have the domain knowledge and best practice expertise that has been put into development of Nauticus Machinery Crankshaft Fatigue software. This crankshaft design and analysis software module calculates the safety against fatigue based on DNV Class Guidelines 0037. It also covers the corresponding calculation method according to IACS Unified Requirements M53.

Crankshaft analysis

Crankshaft analysis of strength consists initially in determining the nominal alternating bending and nominal alternating torsional stresses which, multiplied by the appropriate stress concentration factors using the theory of constant energy of distortion (v. Mises' Criterion), result in an equivalent alternating stress (uni-axial stress). This equivalent alternating stress is then compared with the crankshaft fatigue strength of the selected material. This comparison will then show whether or not the crankshaft concerned is dimensioned adequately, according to the crankshaft analysis.

Crankshaft design is based on an evaluation of safety against crankshaft fatigue in the highly stressed areas. The crankshaft analysis is also based on the assuption that the areas exposed to highest stresses are:

  • fillet transitions between the crankpin and web as well as between the journal and web
  • outlets of crankpin bores
  • outlets of journal oil bores

These crankshaft design and analysis methods apply to engines for both main propulsion and auxiliary purpose, being designed for continous operation at the specified (nominal) rating. If frequent use of overload (in excess of nominal) rating is forseen, i.e. accumulating several millions of stress cycles, this overload should form the basis for the calculation. Further, the methods apply to solid forged or semi-built crankshafts of forged and cast steel, and with one crank throw between main bearings. Design with more than one crank throw between main bearing, fillets between offset crankpins, fully built crankshafts, or welded crankshafts will be specially considered on basis of equivalence with the 'normal' requirements.

Crankshaft Fatigue software from DNV

  • Calculation design and analysis of safety against crankshaft fatigue failure in diesel engines, and safety against slippage for semi built crankshafts
  • Fatigue check based on DNV Class Guidelines 0037
  • Corresponding calculation method according to the IACS method for crankshaft design and analysis
  • Applies to diesel engines for both main propulsion and auxiliary purpose
  • Applies to solid forged per semi built crankshafts of forged and cast steel with one crank throw between main bearings

Key benefits of the crankshaft design and analysis software module

  • Crankshaft Fatigue software calculates according to DNV Rules and IACS requirements in the same crankshaft design tool
  • Import functions for cylinder pressures or theoretical calculation method
  • Flexible input options (use pre-defined input for e.g. stress concentration factors or let the program calculate it)
  • Advanced report generator


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