This paper deals with two aspects of the characterization of the fracture process zone (FPZ) in quasi-brittle materials such as concrete. An overview is given of the possibility of using a destructive technique, such as the scanning electron microscope, and a numerical model, such as the nonlocal isotropic damage model (NLIDM), to detect FPZ characteristics, e.g., length and width of the FPZ. The fracture of concrete requires the consideration of progressive damage, which is usually modelled by a constitutive law and can be studied by a numerical method. The object-oriented finite element method (OOFEM) has recently been used in damage studies, and thus the FPZ is calculated on the basis of one of the damage models (the NLIDM). The results obtained from the experimental investigation are similar to those obtained using the NLIDM, which has proven to be a useful tool for analysis of the cracking process.Key words: object-oriented finite element method, nonlocal isotropic damage model, fracture process zone, scanning electron microscope.
Purpose
The purpose of this paper is to present a new approach for computing by measuring and testing related 3D Eddy currents. In the process, a magnetic vector is formulated from the theoretical setup and obtained results from relevant applications are checked for the consistency of the theory. Besides, cracks detection as well as its propagation is studied through the two parameters: SIF and J-integral. A simulation by a numerical approach using finite-element discretization of 3D governing equations is employed to detect damaged zones and cracks. This approach has been used in the aircraft industry to control cracks. Besides, it makes it possible to highlight the defects of parts while preserving the integrity of the controlled products. Obtained results are compared and agreed with those of other researchers.
Design/methodology/approach
Finite-element discretization of 3D for solving problem in eddy current testing is presented in this paper. The main idea is the introduction of categorization for the shape reconstruction using the non-destructive testing by 3D-EC. The results are presented for a simple eddy current problem using the finite-element method as an experimental support.
Findings
In this research work, results of the various cases of simulation have been obtained. From these results of various boxes of simulation, one can conclude that the calculation of the impedance in only one point is not enough to confirm the presence or the absence of a defect for materials. Then, this confirmation leads us to the calculation of the impedance along the plate. The detection of an external defect requires the energy of the sensor by high frequencies .The position of defect (internal, in the middle, external) has a large effect on the impedance. The use of this sensor type in industrial application is frequent because of its precision (minimal error) and its low costs. The major disadvantage of this type of sensor lies in the fact that it is unable to detect a defect.
Originality/value
This paper fulfills an identified need to detect cracks in materials and eventually to study their propagation.
ABSTRACT. In this paper, we try to use the finite element method of 2-D axisymmetry to solve problems in eddy current testing problems where the main idea is detecting crack's shape using the NDT-EC. Results are given for a simple eddy current problem using the finite element method as a tool to control cracks and defects in materials and eventually, to study their propagation as well as their shape classification. These latest can be described as the task of reconstructing the cracks and damage in a tube's profile of an inspected specimen in order to estimate its material properties. This is accomplished by inverting eddy current probe impedance measurements which are recorded as a function of probe position. This approach has been used in the aircraft industry to control cracks. Besides, it makes it possible to highlight the defects of parts while preserving the integrity of the controlled products.
Purpose
The purpose of this paper is to present a numerical analysis of structural monitoring for damage zones detection. The study is performed with Ansys finite element software, which reads in batch mode programming a previously generated mesh data file and computes the transient dynamic solution for each time-step iteration within an analysis time range.
Design/methodology/approach
The approach itself is applied on a bridge structure which can be potentially subjected to damage zones due to severe loads cases and or earthquakes vibrations. The ideal Von Mises failure criterion ellipsoid envelope is applied for the detection of overstepped computed stresses and strains.
Findings
This numerical analysis allows computing, for each time-step iteration, the dynamic displacements at each degree of freedom and the corresponding stresses and strains inside the elements under the action of several times dependent loads cases.
Practical implications
Several simulations are considered to quantify the external loads.
Originality/value
The material properties of reinforced concrete RC are calculated for an existing specific bridge structure case. The RC strength is then introduced from the basic compounds material properties using the corresponding volumes fractions.
In this paper, a nondestructive technique is used as a tool to control cracks and microcracks in materials. A simulation by a numerical approach such as the finite element method is employed to detect cracks in materials and eventually to study their propagation using a crucial parameter such as the stress intensity factor. This approach has been used in the aircraft industry to control cracks. Besides, it makes it possible to highlight the defects of parts while preserving the integrity of the controlled products. On the other side, it highlights the reliability of the control of defects and gives convincing results for the improvement of the quality and the safety of the material.
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