Methodology for estimating offshore wind turbine fatigue life under combined loads of wind, waves and ice at sub-zero temperatures

Due to increasing trend of building offshore wind turbines (OWTs) in seas at high latitudes where seasonal sea ice occurs, novel methods for design of such structures are needed. Specifically, the effect of ice-induced vibrations (IIVs) on fatigue life of the structures is currently poorly understood. Therefore, the goal of this paper is to...

Fatigue damage in composites under different loading conditions

The damage development In notched (± 45, 0„, 90, 0-) carbon-epoxy coupon specimens tested under different loading conditions was determined. Constant amplitude tests at R = -1 and R = 0.1 as well as flight simulation tests were performed to establish those stress values for which no damage growth occurs.

Standardized environmental fatigue sequence for the evaluation of composite components in combat aircraft (ENSTAFF = ENvironmental FalSTAFF)

Fatigue life assessment of composite structures in fighter aircraft necessitates testing with both mechanical and environmental loading at both coupon and structural element size levels. Testing facilities to run such tests are now available but environmental fatigue testing is expensive and time consuming. An environmental fatigue loading...

The tail of the test spectrum: The effect of different approximations of the lower end of a gust load spectrum on crack growth and fatigue life in 7075-T6 and 2024-T3 specimens

The influence of the approximation of the lower end of the load spectrum was investigated by comparative tests using the Basic F-27 test programme and an extended version, containing three times more cycles per flight. Crack growth was studied on notched sheet specimens made of Alclad 202U-T3 and Alclad TOT5-T6. Fatigue life tests were done on...

The effect of sheet thickness and laminating on the fatigue resistance of the aluminium alloyd AL-7010T73651

The influence of sheet thickness (2 mm and 10 mm) and the influence of laminating (5x2 ram) on the fatigue crack growth properties of the aluminium alloy AL 7010-T 73651 were investigated. Both constant amplitude loading and flight simulation loading were applied. All 2 mm and 10 mm thick sheets were machined from a 150 mm thick plate, i.e....

Engineering property comparisons of the aluminium plate alloys 7050-T7365I, 7010-T7365I and 7010-T765I

The Al-Zn-Mg-Cu alloy 7050 produced by Alcoa is a typical plate and forging alloy because of its low quench sensitivity. In order to compare this alloy with the earlier tested plate alloy 7010 an experimental programme was performed involving tensile, fracture toughness, and fatigue testing. In addition stress corrosion crack initiation and...

The influence of different types of anodic layers on the fatigue properties of 202U-T3 and 7056-T6 sheet material

Constant amplitude and flight simulation fatigue tests have been carried out on sulphuric acid, chromic acid and phosphoric acid anodized specimens. A comparison was made with the fatigue behaviour of bare sheet material. Before fatigue testing the fracture strain of the anodic layers was determined.

Effects of variations in gust spectrum and ground-load level on fatigue life and crack propagation in 70T5-T6 and 202U-T3 specimens

The effects of systematic variations in mean stress level and in spectrum and ground load severity of a flight simulation test programme have been investigated on riveted specimens (fatigue life) and sheet specimens with central saw cut (crack growth). The fatigue life and crack propagation life in Alclad 202U-T3 compared with Alclad TOT5-T6...

Application of finite element methods to the analysis of cracks: final report

The applicability of finite element methods to the analysis of cracks was studied in three phases. In the first phase the available methods for the calculation of elastic stress intensity data for cracks of arbitrary shape using finite element techniques were evaluated. The indirect energy release method using virtual crack front variation was...

Engineering properties of the recently developed aluminium alloy designated 7010

An experimental investigation.was performed on 80 mm thick plate material of 7OIO-T7651 and 7OIO-T73651 developed by Alcan Industries Ltd in U.K. The testing programme involved: tensile tests, fracture toughness, stress corrosion and fatigue tests. For comparison a similar investigation vas carried out on 7075-T7351 Alcoa plate material.

Lasting Friendship: A review of the F-27 fatique evaluation programma carried out by Fokker-VFW

Fokker-VFW is carrying out a completely new fatigue evaluation of the F-2T aircraft, covering lives up to 120000 flights. This evaluation includes; a)A complete inventory of the configuration status of the F-2T fleet, b)An inventory and evaluation of existing test experience, c)Evaluation of service experience, d)Analytical predictions of life...

Influence of corrosion damage on fatigue crack initiation

The influence of previous corrosion on fatigue crack initiation has been determined. Cylindrical specimens and flat specimens with a central hole of the aluminium alloy T075-T6 were corroded in a 3.5 % NaC1 solution. The cylindrical specimens were tested under constant amplitude loading while for the specimens with a central hole a block...