Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Behavior of the distribution of life in notched components according to TCD (Theory of critical distance)
Submission Author:
Jéssica Nayara Dias , DF
Co-Authors:
Jéssica Nayara Dias, JORGE FERREIRA, Letícia Silva
Presenter: Jéssica Nayara Dias
doi://10.26678/ABCM.COBEM2017.COB17-1567
Abstract
The Theory of Critical Distance (TDC) was reformulated to allow life prediction of notched components subjected to multiaxial loads. In this sense, as opposed to the classical approach, a fault function is used which contains information on the tensor of the stresses and/or deformations and admits that the characteristic length, L, varies with the fatigue life. Thus, it is proposed that the failure function is represented by the Smith-Watson-Topper parameter, SWT, in the critical plane. This is accomplished through the calibration and use of a critical distance curve, L - Nf, estimated based on the SWT parameter and subsequent application of critical plane search algorithms. In addition, for the quantification of life distribution behavior, the algorithms for estimating the L - Nf curve and critical plane search were adapted for the use of the Monte Carlo simulation technique. For the validation of the model, a set of experimental data obtained from fatigue tests was used in specimens with and without notches made with the Al 7050-T7451 alloy, under uniaxial loads (push-pull and torsional) and multiaxial loads (torsion -traction). As results, it can be verified that the deterministic predictions of life presented a relatively good agreement when compared to the lives observed experimentally. From the analysis of the life results predicted by the Monte Carlo technique, it was possible to infer that the fatigue lives estimated under multiaxial loading conditions can be represented by lognormal or Weibull distributions, with greater adherence to the lognormal distribution. In addition, when comparing the life time related to the probabilities of failure of 2.5; 50 and 97.5% with the lives obtained experimentally, it was possible to observe that the upper limits are in a good concordance whereas the inferior ones present a significant difference in the region of confidence.
Keywords
fatigue, notched components, critical distance criterion, reliability, Monte Carlo
