Abstract
Approach for numerical simulation of the process of the creep crack growth taking into account the hidden material damage is proposed. The approach is based on the application of finite element creep modeling, accompanied by damage. For calculations, the FEM Creep software package is used. Using the proposed algorithm for rebuilding the grid with the removal of the destroyed elements, the current picture of deformation and fracture is analyzed. This takes into account the growing level of damage during the crack motion in each element. Numerical fracture simulation data are used to determine the constants in the differential creep fracture propagation equation. As an example, the creep fracture of planar specimens with sharp notches in their plane is considered. The material of the specimens is a high-temperature nickel-based alloy EI 867 at a temperature of 950 °C. Calculations are carried out for different values of the load. For different times, finite element grids with remote elements are shown. Graphs of the dependence of crack length on time are built. Comparison of numerical and calculated data obtained with the motion equation of a crack shows their acceptable coincidence. The possibility of using the proposed approach for obtaining constants in the equation of crack motion as an alternative to the existing experimental one is discussed.
Highlights
The prospect of the proposed solution can be considered obtaining the constants of the fracture motion equations from numerical modeling data for the most common types of structural elements
The suitability of the approach is established, accor ding to which the total fracture time of the notched specimens chosen for its demonstration is defined as the sum of the time until the end of the hidden damage in a certain finite element and the time that is necessary to destroy the material in the direction of motion of macrodefect
The use of the Finite Element Method together with the numerical integration of the system of differential equations allows to track the complete picture of the fracture in the plane and in time by eliminating the «destroyed» elements
Summary
Ensuring the reliability and durability of elements of modern aerospace equipment, steam and gas turbines, etc. requires the creation of effective methods of computational analysis. The authors consider the theoretical achievements of Fracture Mechanics in the form of fracture motion equations, kinetic equations for scalar and tensor damage parameters, and the like These approaches and methods can be applied to the analysis of the behavior of real structures, but the monograph does not spe cify an example of the corresponding solved problems. At present, the problem of the fracture of structural elements operating under creep conditions in a complex stress state requires the decomposition of existing and the development of new approaches. Such approaches have links between the methods of Continuum Damage Mechanics and Fracture Mechanics. This makes it possible to design more reliable equipment – steam and gas turbines, gas turbine engines, liquid jet engines and the like
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
