Environmental Engineering Reference
In-Depth Information
5.10.5
Optimizing Overall Durability Performance
Wind. turbines. are. designed. to. cover. a. 20-year. lifetime. with. low. operat-
ing. and. maintenance. costs,. and. to. withstand. the. high. variability. of. wind.
forces.. To. meet. these. targets,. engineering. teams. apply. durability. analysis.
using. loads. measured. through. testing. or. obtained. from. dynamic. simula-
tion..The.critical.loads.acting.on.a.wind.turbine.are.mainly.due.to.luctua-
tions.in.speed.and.direction.of.the.wind.and.by.the.starting.and.stopping.
of.the.system..The.number.of.load.cases.typically.varies.between.50.and.500.
and.last.up.to.10.minutes.each.
LMS Virtual.Lab. Durability. provides. the. batch. capability. to. eficiently.
analyze. the. different. load. cases. independently. or. on. remote. CPUs. with.
advanced.monitoring.capabilities.and.e-mail.notiications.at.the.end.of.the.
job.. Starting. from. the. external. loads,. Virtual.Lab. computes. internal. loads.
acting.on.the.components,.such.as.the.rotor.hub.(Figure 5.14)..A.global.load.
spectrum. formulated. from. individual. events. is. then. used. to. simulate. 20.
years.of.use.
Traditionally,. only. the. static. loads. and. a. maximum. stress. criterion. are.
applied,. not. taking. into. account. the. unpredictable. random. forces,. or. the.
interrelationships.of.multiaxial.forces..This.oversimpliication.leads.to.inac-
curate,. fatigue-life. predictions,. and. the. only. way. to. secure. the. operational.
safety.of.the.turbine.was.to.over-design.it..By.ignoring.the.phasing.relations,.
the.conclusions.may.even.identify.the.wrong.hotspots.
LMS.Virtual.Lab.Durability.provides.accurate.fatigue.life.predictions.and.
results. are. calculated. very. eficiently.. The. time. history. approach. uses. all.
signiicant. damaging. events. and. automatically. accounts. for. correct. phase.
Optimizing Overall Durability Performance
1200
Column A
Column B
1000
800
600
400
200
0
1
2
3
4
5
Level of stress
FIGURE 5.14
Optimizing.overall.durability.performance.
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