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Wind energy fatigue test programme. Report on fatigue strength assessment on weld details

Technical Report:

Abstract

Vibration fatigue tests (constant amplitude, zero mean stress) have been carried out on 20 `real size` welded I beam specimens representative of the 60 metre diameter horizontal axis wind turbine rotor manufacture, to investigate the relationship between Non-destructive Testing (NDT) and Fatigue Loading in respect to life. Three areas were looked at which are relevant to the fatigue life of the 60m Blade, using these unstress relieved specimens (simulating on-site fabrication and repair). Firstly, the correlation between NDT determined weld defect geometry and fatigue life was considered. It is concluded that knowing defect sizes, geometry and location does not allow direct prediction of the failure site nor determination of its actual life. It was noted that all the endurances obtained in these tests were significantly better than the BS5400 guide lines, particularly for endurances in excess of 10{sup 7} cycles. Secondly, the effect of infrequent high loads on fatigue life was considered. It was found that excursions up to 20% above `base` bending stress levels, at a frequency of 10{sup 3} cycles in every 10{sup 6} at `base` level, appeared to have no significant effect on life for the two specimens tested. Finally, the efficiency of welded repairs was examined.  More>>
Authors:
Publication Date:
Dec 31, 1992
Product Type:
Technical Report
Report Number:
ETSU-WN-5084
Reference Number:
SCA: 170602; PA: GB-92:053411; SN: 93000926065
Resource Relation:
Other Information: PBD: 1992
Subject:
17 WIND ENERGY; HORIZONTAL AXIS TURBINES; FATIGUE; TURBINE BLADES; WELDED JOINTS; SERVICE LIFE; REPAIR; FAILURES; CRACKS; NONDESTRUCTIVE TESTING; 170602; TURBINE DESIGN AND OPERATION
OSTI ID:
10117321
Research Organizations:
Wind Energy Group Ltd., Southall (United Kingdom); British Aerospace Dynamics Group, Stevenage (United Kingdom)
Country of Origin:
United Kingdom
Language:
English
Other Identifying Numbers:
Other: ON: DE93759147; CNN: Contract E/5A/CON5084/1419; TRN: GB9253411
Availability:
OSTI; NTIS (US Sales Only)
Submitting Site:
GB
Size:
116 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Baines, P J. Wind energy fatigue test programme. Report on fatigue strength assessment on weld details. United Kingdom: N. p., 1992. Web.
Baines, P J. Wind energy fatigue test programme. Report on fatigue strength assessment on weld details. United Kingdom.
Baines, P J. 1992. "Wind energy fatigue test programme. Report on fatigue strength assessment on weld details." United Kingdom.
@misc{etde_10117321,
title = {Wind energy fatigue test programme. Report on fatigue strength assessment on weld details}
author = {Baines, P J}
abstractNote = {Vibration fatigue tests (constant amplitude, zero mean stress) have been carried out on 20 `real size` welded I beam specimens representative of the 60 metre diameter horizontal axis wind turbine rotor manufacture, to investigate the relationship between Non-destructive Testing (NDT) and Fatigue Loading in respect to life. Three areas were looked at which are relevant to the fatigue life of the 60m Blade, using these unstress relieved specimens (simulating on-site fabrication and repair). Firstly, the correlation between NDT determined weld defect geometry and fatigue life was considered. It is concluded that knowing defect sizes, geometry and location does not allow direct prediction of the failure site nor determination of its actual life. It was noted that all the endurances obtained in these tests were significantly better than the BS5400 guide lines, particularly for endurances in excess of 10{sup 7} cycles. Secondly, the effect of infrequent high loads on fatigue life was considered. It was found that excursions up to 20% above `base` bending stress levels, at a frequency of 10{sup 3} cycles in every 10{sup 6} at `base` level, appeared to have no significant effect on life for the two specimens tested. Finally, the efficiency of welded repairs was examined. It is concluded that for the five specimens repaired there was a general reduction in endurance relative to the as-manufactured life but still within the scatter band for all the specimens tests in this programme, so this reduction is not serious. (author).}
place = {United Kingdom}
year = {1992}
month = {Dec}
}