Computational fracture mechanics: An overview from early efforts to recent achievements

Abstract

An overview of the state of the art of computational fracture mechanics is presented, starting from early efforts and going all the way up to recent achievements. Some specific aspects of linear elastic and elastic plastic fracture mechanics problems have been discussed, including the fact that even for a static loading, numerical simulation is not a simple task because of complex geometries, material nonlinearity, and heterogeneity, and especially if crack growth is considered. Therefore, micromechanical modelling of elastic‐plastic crack growth is presented as new and promising approach to overcome some of the shortages of traditional approach. Besides static loading, couple of other important practical problems are tackled, like fatigue crack growth, with remaining life in the focus of investigation, using the empirical laws for crack growth rates. Numerical simulation of fatigue crack growth is inherently complex both because of complex material damage processes and lack of sound theoretical basis to define them. Therefore, combination of theoretical, experimental, and numerical approach is presented here to get reliable and efficient estimation of life under fatigue loading.

Structural Integrity Assessment of Welded Pipeline Designed with Reduced Safety

“…In this case, mechanical properties were defined for the parent material (Yield Strength 760 MPa) and two weld metals, which had somewhat different Yield Strengths, 687 MPa for SAW and 725 MPa for MAW. Other properties were defined as for the true stress -true strain curves, in a way explained in more details in [19].…”

Design aspects of light aircraft wing spar—Differential and integral approach

“…This method suppresses the need to mesh and remesh the crack surfaces and is used for modelling different discontinuities in 1D, 2D, and 3D domains. The XFEM has successfully being used to calculate stress intensity factors (SIFs) for problems involving multiple, interacting cracks, resulting from multiple site damage (MSD), as well as for simulating crack paths development in more complex models …”

“…Then, I cross‐section integral spar was redesigned to include one IC (flange). As already mentioned, this case is represented in three types, IC1, IC2, and IC3, with different dimensions to optimize the size . As mentioned before, the aim of this investigation was to optimize wing spar cross‐section shape and size, based on fatigue life, ie, SIFs.…”

“…Corresponding number of Kilocycles (ie, fatigue life) are cca 330 for IC1, 440 for IC2, and 1370 for IC3, being, once again, far the best. More details about fatigue life for both differential and integral design are given in other works …”

Verification of a cohesive model‐based extended finite element method for ductile crack propagation

“…The classifications of cohesive laws have been discussed in great detail by, for example, Park et al 17 and Kuna et al 18 The main shortcoming of the cohesive models is that the cohesive elements need to be predefined along the element boundaries, which would make the simulated results are sensitive to the predefined area 7,20 . One of the novel approaches to overcome the above mentioned limitations is to couple the cohesive model with the extended finite element method (XFEM), which can trace the advanced crack‐tip without known the crack path in prior and the cohesive crack areas will not be overestimated 21,22 . Since 1999, the XFEM has been extensively used to simulate the brittle and ductile failure with different kinds of damage models 23–27 .…”