Scale Bridging in Computational Modelling of Quasi-Brittle Fracture of Cementitious Composites

2021 ◽  
Vol 325 ◽  
pp. 59-64
Author(s):  
Jiří Vala ◽  
Vladislav Kozák ◽  
Michal Jedlička
Keyword(s):  
Steel Fibre ◽  
Mathematical Formulation ◽  
Computational Modelling ◽  
Computational Prediction ◽  
Cohesive Crack ◽  
Short Paper ◽  
Cementitious Composites ◽  
Extended Finite Element ◽  
Convergence Results ◽  
Potential Initiation

Computational prediction damage in cementitious composites, as steel fibre reinforced ones, under mechanical, thermal, etc. loads, manifested as creation of micro-fractured zones, followed by potential initiation and evolution of macroscopic cracks, is a rather delicate matter, due to the necessity of bridging between micro-and macro-scales. This short paper presents a relatively simple approach, based on the nonlocal viscoelasticity model, coupled with cohesive crack analysis, using extended finite element techniques. Such model admits proper verification of its existence and convergence results, from the physical and mathematical formulation up to software implementation of relevant algorithms. Its practical applicability is documented on a sequence of representative computational examples.

Damage detection based on system identification of concrete dams using an extended finite element–wavelet transform coupled procedure

2017 ◽  
Vol 24 (18) ◽  
pp. 4226-4246 ◽  
Author(s):  
Sajjad Pirboudaghi ◽  
Reza Tarinejad ◽  
Mohammad Taghi Alami
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wavelet Transform ◽  
System Identification ◽  
Damage Detection ◽  
Cohesive Crack ◽  
Modal Parameters ◽  
Concrete Dams ◽  
Extended Finite Element ◽  
Element Method

The aim of the present study is to propose a procedure for seismic cracking identification of concrete dams using a coupling of the extended finite element method (XFEM) based on cohesive crack segments (XFEM-COH) and continuous wavelet transform (CWT). First, the dam is numerically modeled using the traditional finite element method (FEM). Then, cracking capability is added to the dam structure by applying the XFEM-COH for concrete material. The results of both the methods under the seismic excitation have been compared and identified to damage detection purposes. In spite of predefined damage in some of the structural health monitoring (SHM) techniques, there is an advantage in the XFEM model where the whole dam structure is potentially under damage risk without initial crack, and may not crack at all. Finally, in order to evaluate any change in the system, that is, specification of any probable crack effects and nonlinear behavior, the structural modal parameters and their variation have been investigated using system identification based on the CWT. The results show that the extended finite element–wavelet transform procedure has high ability for the online SHM of concrete dams that by analysis of its results, the history of physical changes, cracking initiation time, and exact damage localization have been performed from comparing the intact (FEM) and damaged (XFEM) modal parameters of the structural response. In addition, any small change in the system is observable while the final crack profile and performance simulation of the dam body under strong seismic excitations have obtained.

scholarly journals Hydroinformatics and its applications at Delft Hydraulics

1999 ◽  
Vol 1 (2) ◽  
pp. 83-102 ◽  
Author(s):  
Arthur E. Mynett
Keyword(s):  
Mathematical Formulation ◽  
Computational Modelling ◽  
Free Surface Flows ◽  
Historical Background ◽  
Geographical Information ◽  
Staggered Grid ◽  
Engineering Practice ◽  
Courant Number ◽  
Recent Advances ◽  
Wide Range

Hydroinformatics concerns applications of advanced information technologies in the fields indeed the very success of hydroinformatics is directly associated with these applications. The aim of this paper is to provide an overview of some recent advances and to illustrate the practical implications of hydroinformatics technologies. A selection of characteristic examples on various topics is presented here, demonstrating the practical use at Delft Hydraulics. Most surely they will be elaborated upon in a more detailed way in forthcoming issues of this Journal. First, a very brief historical background is outlined to characterise the emergence and evolution of hydroinformatics in hydraulic and environmental engineering practice. Recent advances in computational hydraulics are discussed next. Numerical methods are outlined whose main advantages lie in their efficiency and applicability to a very wide range of practical problems. The numerical scheme has to adhere only to the velocity Courant number and is based upon a staggered grid arrangement. Therefore the method is efficient for most free surface flows, including complex networks of rivers and canals, as well as overland flows. Examples are presented for dam break problems and inundation of polders. The latter results are presented within the setting of a Geographical Information System. In general, computational modelling can be viewed as a class of techniques very much based on, and indeed quite well described by, mathematical equations. These equations often symbolically represent underlying physical phenomena, like conservation of mass, momentum and energy. Diversification to application areas where no clear mathematical formulation may (yet) be present but where adequate data sets are available is illustrated by several practical examples. Again, using computer based technologies, various applications of so-called sub-symbolic techniques like Artificial Neural Networks (ANNs) are discussed and presented. Finally, some reflections on forthcoming developments and likely implications for engineering practice as well as education are outlined.

scholarly journals Cast3M implementation of the extended finite element method for cohesive crack

2011 ◽  
Vol 33 (1) ◽  
pp. 55-64
Author(s):  
Nguyen Truong Giang ◽  
Ngo Huong Nhu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fracture Mechanics ◽  
Extended Finite Element Method ◽  
Brittle Materials ◽  
Cohesive Crack ◽  
Numerical Calculations ◽  
Extended Finite Element ◽  
Element Method

In this paper, the finite element for cohesive crack for quasi-brittle materials is constructed by the displacement discontinuities in the element. The algorithm of construction and procedures for involving this finite element into code Cast3M are presented. The numerical calculations in fracture mechanics are presented to demonstrate the benefits of the proposed implementation.

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