Low-Cycle Fatigue Simulation and Life-Time Prediction of High Stressed Structures

Abstract

The problem of mathematical simulation of the origin and evolution of low-cycle fatigue cracks is quite actually for many high-loaded machines and units of power industry, aerospace engines, oil and gas pipelines and other structures operating under repeated loading. Successful prediction of low-cycle resource depends on solution of several interrelated problems: creation and development of structure model (loads, boundary conditions, materials model) that will adequately describe all aspects stress-strain history in the structures paths; creation plasticity and creep models adequate to the processes taking place during sing-alternating elastic-plastic deformation; the creation of lifetime fatigue failure rate criteria; and development of effective numerical simulation technique.

Simulation of Thermomechanical Fatigue of Structured Materials

“…Nomenclature correlates with works [1][2][3][4]. In [1,2] based on experimental results it was determined that at room temperature number of halfcycles to failure for several structural materials under various loading programs (soft loading, hard loading, random loading) n f and damage D depends on ultimate value max by next relation:…”

“…The technology of simulation of low cycle fatigue of specimens and parts was originally developed under isothermal cyclic loading conditions [1,2]. Generalization of this technology of the simulation under nonisothermal cyclic loading was proposed in works [3,4] .…”

Low-Cycle Fatigue Simulation Under Nonisothermal Loading

“…В процессе расчета на каждом шаге в элементе определяется текущая повреждаемость = q( )/q max ( ). При приближении повреждаемости в элементе к единице, элемент исключается из расчета с использованием технологии «отмирающих» элементов [9].…”

“…Для анализа НДС и оценки ресурса деталей турбомашин модель циклической пластичности и разрушения при неизотермическом нагружении реализована в конечноэлементном комплексе [9], который применен для моделирования малоцикловой усталости турбинной лопатки (рис. 12, а).…”

Thermal-Fatigue Analysis of Turbine Discs under Complex Thermo-Mechanical Loading with Account of Plasticity and Creep Effects

“…A verification of the proposed approach have been performed in comparison with results of full-scale tests with overloading up to a fracture [1,7,8]. Alternative approaches are considered in [9][10][11][12][13][14][15][16][17][18][19].…”