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Fatigue is modeled as a smooth of the normalized input u which is indicating the current workload with regard to capital equipment or workers. The current workload will be normalized by dividing the input u by a constant or a variable reference workload (referenceWorkload or u_ref, respectively). The timeToGetFatigued describes the time constant for the smooth and indicates the lag between beginning to work at an excessive level and the onset of the full effect on productivity (or quality).

Janoscheks growth curve is used to model the nonlinear effect of a prolonged work intensity. It describes a negatively sloping s-shaped curve that will pass through the reference point (1,1). The upper bound of the effect (effectMax) must be given slightly above 1.0 as the curve will collapse in all other cases. If the effect is to be clipped at 1.0 then the parameter clipEffect should be set to true.

Notes

• The workload (and its reference value) will typically be some rate (e.g., hours worked per month, output per hour etc.).
  
  
• Jim Hines [6, p. 82] uses overtime as the main driver of fatigue. See also on his Molecules of Structure website (→Effect of Fatigue).


• The parameter init in the Advanced tab allows to select →InitializationOptions:
  
  • FixedValue (default) will use the parameter initialFatigue to determine the initial output of the smoothed, normalized workload.
  
  
  • SteadyState will set the initialFatigue to the normalized workload at the start of the simulation.
  
  
  • Free there will be no initial equation and thus the solver is free to find an initial value for fatigue using initialFatigue as an initial guess.

See also

SmoothN, JanoschekNegative