PRObability distribution of FAtigue strength of Rotor blades: PROFAR
Static and fatigue tests have been performed on coupons to derive material properties and strength distribution as a basis for further analysis.
Within the Profar project 27 fatigue tests and 8 static tests have been performed.
From the FACT database 39 useful tests have been selected for comparison with Profar data.
Static and fatigue tests on rotor blades:
Flapwise prismatic tip section
Flapwise root section
Edgewise root section
Static and fatigue tests on coupons:
Fatigue R= 0.1
Fatigue R= -1
Fatigue formulation with Goodman modification.
Comparison coupon data with existing data from literature.
Non-linear regression analysis of coupon results based on maximum stress for the whole population R=0.1 and R=-1; slope and UTS value are the results.
Typical creep and stiffness development during coupon fatigue test
Results of R=-1 tests fitted with a fatigue formulation using a Goodman modification using multiple non linear regression
Fatigue formulation with Goodman modification describes influence of stress ratio very well.
PROFAR test results are in good agreement with FACT results when divided by the UTS-value of the relevant material.
Slopes of regression lines are close to 10 for blade and coupon tests as well.
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