Damage evolution in the AMg6 alloy during high and very high cycle fatigue

Abstract

Paper presents the "in situ" method for determining of irreversible fatigue damage accumulation, based on the analysis of nonlinear manifestations of the feedback signal in a closed system of an ultrasonic fatigue system. During very high cycle (gigacycle) fatigue, the anomalies of the elastic properties of the material are appear, which leads to a nonlinearity effect in the amplitude of oscillations. This effect increases with the initiation and growth of fatigue cracks. The technology was applied to samples of AlMG-6 alloy with preliminary dynamic deformation to determine the moment of initiation and growth of the fatigue crack in very high cycle fatigue regime. This method is applicable for the early detection of fatigue cracks both on the surface and inside the material under cyclic loading in the ultrasonic mode. On the basis of wide-range defining relations for a deformable solid body with mesoscopic defects, a mathematical model has been proposed that can adequately describe behavior of the material during fatigue failure. The results of mathematical modeling are in good agreement with the experimental data

Critical Dynamics of Defects and Mechanisms of Damage-Failure Transitions in Fatigue

“…1 gave qualitatively consistent results on the number of cycles that went into nucleation and crack growth: 6.91∙× 10 8 to nucleation; 0.56∙× 10 6 for growth in zone 2; and 0.58∙× 10 6 for growth in zone 3. The simulation of the behavior of the second harmonic during the experiment was carried out in [ 23 ].…”

ChISLENNOE MODELIROVANIE NAKOPLENIYa POVREZhDENNOSTI V METALLAKh PRI TsIKLIChESKOM DEFORMIROVANII

“…В связи с этим возникает задача оценки усталостного ресурса на этапе проектирования. Наряду с экспериментальными методами прогнозирования роста усталостных трещин [1][2][3] используют также и расчѐтные методики для отслеживания эволюции повреждѐнности [2][3][4].…”

“…(2) В (1)-(2) приняты следующие обозначения: p -компонента тензора плотности микродефектов, σ A -амплитуда приложенных напряжений, ν -частота нагружения, Γ p Γ pσположительные коэффициенты, константы материала [2].…”

Experimental study of damage accumulation staging in gigacycle fatigue of aviation motors materials

“…Широкодиапазонные определяющие соотношения [22][23][24], описывающие связь кинетики поврежденности, обусловленной дефектами, с релаксационными свойствами материалов, использованы для построения математической модели, способной описывать деформационное поведение металлов и сплавов при усталостном нагружении.…”