A model of crack opening stresses in variable amplitude loading using smooth specimen fatigue test data for three steels

A new vibration-based multiaxial fatigue testing methodology for assessing high cycle turbine engine material fatigue strength at various stress ratios is presented. The idea is to accumulate fatigue energy on a base-excited plate specimen at high frequency resonant modes and to complete a fatigue test in a much more efficient way at very low cost. The methodology consists of: (1) a topological design procedure, incorporating a finite element model, to characterize the shape of the specimens for ensuring the required stress state/pattern, (2) a vibration feedback empirical procedure for achieving the high cycle fatigue experiments with variable-amplitude loading, and finally (3) a yielding procedure for achieving various uniaxial stress ratios. The performance of the methodology is demonstrated by the experimental results from mild steel, 6061-T6 aluminum, and Ti-6Al-4V plate specimens subjected to fully reversed bending for both uniaxial and biaxial stress states. Results are compared with those produced using traditional fatigue test machines.

Download Full-text

Observing Load Sequence Effects on Simulated and Experimental Fatigue Crack Growth Occurrence

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.462-463.489 ◽

2011 ◽

Vol 462-463 ◽

pp. 489-494 ◽

Cited By ~ 4

Author(s):

S.M. Beden ◽

Shahrum Abdullah ◽

Ahmad Kamal Ariffin ◽

Nawar A. Kadhim

Keyword(s):

Fatigue Crack ◽

Fatigue Life ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Test Data ◽

Growth Models ◽

Load Cycle ◽

Engineering Structures ◽

Variable Amplitude Loading ◽

Variable Amplitude

Load cycle interactions can have a significant effect in fatigue crack growth (FCG) under variable amplitude loading. Studying of FCG and fatigue life calculation under spectrum loading is important for the reliable life prediction of engineering structures. Many models have been proposed, but yet no universal model exists. In this paper, a fatigue life predicted under various load spectra, using three different fatigue crack growth models namely, the Austen, modified Forman and NASGRO models. These models are validated with fatigue crack growth test data under various amplitude loadings. This application is performed with aids of three-point bend specimens of ASTM A533 steel material. The results clearly show the load sequences effect and the predicted results agree with some discrepancies between the different models as well as with the test data. Thus, neglecting the effect of cycle interaction in fatigue calculations under variable amplitude loading can lead to invalid life predictions.

Download Full-text

Crack Opening Stresses Under Constant and Variable Amplitude Loading Determined by Finite Element Analyses

Fatigue '96 ◽

10.1016/b978-008042268-8/50054-x ◽

1996 ◽

pp. 1075-1080 ◽

Cited By ~ 1

Author(s):

R.J. Anthes ◽

J.W. Rodriguez-ocaña ◽

T. Seeger

Keyword(s):

Finite Element ◽

Crack Opening ◽

Finite Element Analyses ◽

Variable Amplitude Loading ◽

Variable Amplitude

Download Full-text

FATIGUE CRACK PROPAGATION BEHAVIOR OF 2091 T8 AND 2024 T3 UNDER CONSTANT AND VARIABLE AMPLITUDE LOADING

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1987394 ◽

1987 ◽

Vol 48 (C3) ◽

pp. C3-801-C3-807 ◽

Cited By ~ 3

Author(s):

N. OHRLOFF ◽

A. GYSLER ◽

G. LÜTJERING

Keyword(s):

Fatigue Crack ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Variable Amplitude Loading ◽

Variable Amplitude ◽

Fatigue Crack Propagation Behavior ◽

Propagation Behavior ◽

Crack Propagation Behavior

Download Full-text

Application of the Strip Yield Model to Crack Growth Predictions for Structural Steel

Archive of Mechanical Engineering ◽

10.2478/v10180-010-0001-3 ◽

2010 ◽

Vol 57 (1) ◽

pp. 1-20

Author(s):

Małgorzata Skorupa ◽

Tomasz Machniewicz

Keyword(s):

Structural Steel ◽

Crack Growth ◽

Model Calibration ◽

Load History ◽

Yield Model ◽

Variable Amplitude Loading ◽

Variable Amplitude ◽

Constraint Factors ◽

Strip Yield Model ◽

Closure Mechanism

Application of the Strip Yield Model to Crack Growth Predictions for Structural SteelA strip yield model implementation by the present authors is applied to predict fatigue crack growth observed in structural steel specimens under various constant and variable amplitude loading conditions. Attention is paid to the model calibration using the constraint factors in view of the dependence of both the crack closure mechanism and the material stress-strain response on the load history. Prediction capabilities of the model are considered in the context of the incompatibility between the crack growth resistance for constant and variable amplitude loading.

Download Full-text