Author: John F. WardPublisher:
ISBN:
Category : Loads (Mechanics)
Languages : en
Pages : 14
Book Description
A Note on Helicopter Rotor-blade Fatigue-crack Propagation Rates Under Equivalent-lifetime Fatigue Loadings
Author: John F. WardPublisher:
ISBN:
Category : Loads (Mechanics)
Languages : en
Pages : 14
Book Description
A Note on Helicopter Rotor-blade Fatigue-crack Propagation Rates Under Equivalent-lifetime Fatigue Loadings
Author: John F. WardPublisher:
ISBN:
Category :
Languages : en
Pages : 1
Book Description
Results are given for a brief investigation of the relative rates of fatigue-crack propagation obtained in helicopter-rotor-blade fatigue tests in which simplified, equivalent-total-lifetime, fatigue-test loadings at zero mean load are used to simulate a flight fatigue loading that includes a mean tension load. The conventional equivalent-lifetime loadings do not give equivalent rates of crack propagation. For typical rotor-blade loadings, which included large mean tension load, the general trend was toward greatly reduced rates of fatigue-crack propagation under the equivalent-lifetime loadings provided a nonconservative basis for establishing rotor-blade inspection intervals. (Author).
NASA Technical Note
Author: Applied Mechanics Reviews
Author: Crack Propagation in Helicopter Rotor Blades
Author: M. J. RICHU.S. Government Research Reports
Author: The Effect of Periodic Overloads on Flight-by-flight Fatigue Crack Growth Rates
Author: Margery A. DeanPublisher:
ISBN:
Category : Airframes
Languages : en
Pages : 38
Book Description
The life prediction of aerospace structures subjected to service loading conditions can be complex and expensive. Fortunately, many flight-by- flight loadings can be analyzed as constant amplitude loading if the variability in crack growth rate is low. A test program was designed such that the stress intensity factor (Kmax) was held constant by uniformly reducing the load as the fatigue crack grew. With a constant Kmax, the crack growth rate remains constant throughout the life of the test. The baseline fatigue crack growth rate variability was established for the 7075-T6 center-cracked panels under a flight-by-flight load history. The effect of introducing overloads to the baseline flight history on the crack growth rate variability was reported. The results indicate that the delay region for the applied 114% overloads was predicted by Irwin's plastic zone model and was equal to 0.0382 inches which was equal to 225 flights. The delay behavior was consistent for the several overload conditions that were studied. When the occurrence of overload increased, the fatigue crack growth decreased. The standard error of estimate remained relatively constant, suggesting that a block approach to life prediction is feasible for flight-by-flight load history.
Technical Publications Announcements with Indexes
Author: United States. National Aeronautics and Space AdministrationPublisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1318
Book Description
Monthly Catalog of United States Government Publications
Author: Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 1990
Book Description
Author: