Free vibration analysis of porous functionally graded plates using a novel Quasi-3D hyperbolic high order shear deformation theory

In this study, a novel quasi-three dimensional hyperbolic high-order shear deformation theory (quasi-3D HHSDT) is developed for free vibration analysis of porous functionally graded plates (FGPs). There are six unknowns in the current displacement field, and no shear correction factor is required. The mechanical properties are varied continuously through the thickness of porous FG plates using a modified power law function while considering the effect of porosities on the plate�s structural integrity. Two distinct porosity distribution models are considered, including even and uneven porosity distributions. The Navier technique is employed to obtain the closed-form solutions of motion's equations. An exhaustive parametric study is presented to show the influence of the different parameters on the fundamental frequencies

Numerical study of semi-elliptical cracks in the critical position of pipe elbow

Pipelines are considered as a major tool to transport hydrocarbons due to its important role in transporting fluids taking into account the operating conditions. Despite the importance of the elbow which considered as a critical part in the pipelines, the repeated failures and defects became a dangerous and enormously costly issue. In this numerical study, the Fluid-Structure Interaction (FSI) analysis was carried out using Ansys software. This work is divided into four main parts: the first part focused on studying and comparing the effect of bending radius of pipe elbow on the maximum of Von-Mises stress values for each radius with the yield stress of the steel of the pipe. The second part focused on the creation of a semi-elliptical crack for different locations along the elbow angles to show the critical position compared to the stress intensity factors. In the third part, the semi-elliptical crack angle orientation was studied at the critical position to estimate the critical angle. In the last part, the failure assessment diagram (FAD) was used to show the critical crack depth ratios at a critical position and a critical angle

Approche globale à deux paramètres (K[rhô]-T[rhô]) : estimation des contraintes de confinements dans des structures portant des entailles

The importance of the two-parameter approach in linear eleastic fracture mechanics analysis is increasingly being recognized for fracture assessments in engineering applications. The consideration of the second parameter, namely, the elastic T-stress, allows estimating the level of constraint at a crack or notch tip. It is important to provide T-stress solutions for practical geometries in order to employ the constraint-based fracture mechanics methodology. In the present research, T-stress solutions are provided for a U-shaped notch in the case of four specimens : CT, DCB, SENT and Romain Tile. The U-shaped notch is analyzed using the finite element method by the commercial Castem 2000 software to determine the stress distribution ahead of the notch tip. The notch aspect ratio was varied : a/w = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7. The notch-tip radius was fixed for all geometries and equal 0.25 mm. In contrast to a crack, it was found that the T-stress is not constant and depends on distance from the notch-tip. To estimate the T-stress in the case of a notch, a novel method, namely, method of line, inspired from the volumetric effective distance ahead of the notch tip. The effective distance corresponds to the point with a minimum of the stress gradient in the fracture process zone. Thus, the two-parameter approach was adopted for the notch two-parameter fracture mechanics in terms of the notch stress intensity factor Kpc and the effective (average) T-stress, Teff. Fracture toughness transferability curve (Kpc-Teff) of X52 pipe steels has been established. This approach was successfully used to quantify the constraints of notch-tip fields for various geometries and loading conditions. Moreoveer, the proposed T-stress estimation creates a basis to analyse the crack path under mixed mode loading from viewpoint of the two-parameter fracture mechanicsL'importance de l'approche globale à deux paramètres dans l'analyse de mécanique linéaire élastique de la rupture est de plus en plus reconnue pour des évaluations de fracture dans des applications d'ingénierie. La considération du deuxième paramètre, à savoir la contrainte élastique T, ou T-stress en anglais, permet d'évaluer le niveau de confinement à la pointe de la fissure où d'entaille. Il est important de fournir des solutions de la contrainte T pour une pratique géométrie pour employer la mécanique de la rupture à base de contrainte de confinement. Dans la présente recherche, nous fournissant des solutions de la contrainte T pour une entaille en forme de U dans le cas de quatre éprouvettes : CT, DCB, SENT et Tuile Romaine. L'entaille en forme de U est analysée utilisant la méthode d'élément finie par le code de calcul Castem 2000 pour déterminer la distribution de contraintes à la pointe de l'entaille et le long du ligement. Le rapport du profondeur du défaut sur l'épaisseur a été varié : a/w = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 et 0.7. Le rayon de l'acuité de l'entaille a été fixé pour toute la géométrie à 0.25 mm. Contrairement aux fissures, il a été trouvé que la contrainte T n'est pas constante et dépend de la distance de la pointe de l'entaille. Pour évaluer cette contrainte dans le cas d'une entaille, une nouvelle méthode, à savoir, la méthode de ligne, inspirée de l'approche de méthode volumétrique proposée par pluvinage a été développée. La méthode est basée sur la détermination d'une contrainte moyenne T sur une distance effective en avant de la pointe de l'entaille. Ainsi, l'approche à deux paramètres a été adoptée pour la mécanique de la rupture à deux paramètres pour les entailles en termes du Facteur d'Intensité de Contraintes d'entaille Kpc et la contrainte moyenne (effective) Teff. La courbe de transférabilité de ténacité à la rupture (Kpc -Teff) dans l'acier de pipeline X52 a été établi. Cette approche a été utilisée avec succès pour évaluer quantitativement le champ des confinements à la pointe de l'entaille pour des différentes géométries et conditions de chargement

Two-parameter approach (K[rhô]-T[rhô]) : constraint effects in structural with notches

L'importance de l'approche globale à deux paramètres dans l'analyse de mécanique linéaire élastique de la rupture est de plus en plus reconnue pour des évaluations de fracture dans des applications d'ingénierie. La considération du deuxième paramètre, à savoir la contrainte élastique T, ou T-stress en anglais, permet d'évaluer le niveau de confinement à la pointe de la fissure où d'entaille. Il est important de fournir des solutions de la contrainte T pour une pratique géométrie pour employer la mécanique de la rupture à base de contrainte de confinement. Dans la présente recherche, nous fournissant des solutions de la contrainte T pour une entaille en forme de U dans le cas de quatre éprouvettes : CT, DCB, SENT et Tuile Romaine. L'entaille en forme de U est analysée utilisant la méthode d'élément finie par le code de calcul Castem 2000 pour déterminer la distribution de contraintes à la pointe de l'entaille et le long du ligement. Le rapport du profondeur du défaut sur l'épaisseur a été varié : a/w = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 et 0.7. Le rayon de l'acuité de l'entaille a été fixé pour toute la géométrie à 0.25 mm. Contrairement aux fissures, il a été trouvé que la contrainte T n'est pas constante et dépend de la distance de la pointe de l'entaille. Pour évaluer cette contrainte dans le cas d'une entaille, une nouvelle méthode, à savoir, la méthode de ligne, inspirée de l'approche de méthode volumétrique proposée par pluvinage a été développée. La méthode est basée sur la détermination d'une contrainte moyenne T sur une distance effective en avant de la pointe de l'entaille. Ainsi, l'approche à deux paramètres a été adoptée pour la mécanique de la rupture à deux paramètres pour les entailles en termes du Facteur d'Intensité de Contraintes d'entaille Kpc et la contrainte moyenne (effective) Teff. La courbe de transférabilité de ténacité à la rupture (Kpc -Teff) dans l'acier de pipeline X52 a été établi. Cette approche a été utilisée avec succès pour évaluer quantitativement le champ des confinements à la pointe de l'entaille pour des différentes géométries et conditions de chargementsThe importance of the two-parameter approach in linear eleastic fracture mechanics analysis is increasingly being recognized for fracture assessments in engineering applications. The consideration of the second parameter, namely, the elastic T-stress, allows estimating the level of constraint at a crack or notch tip. It is important to provide T-stress solutions for practical geometries in order to employ the constraint-based fracture mechanics methodology. In the present research, T-stress solutions are provided for a U-shaped notch in the case of four specimens : CT, DCB, SENT and Romain Tile. The U-shaped notch is analyzed using the finite element method by the commercial Castem 2000 software to determine the stress distribution ahead of the notch tip. The notch aspect ratio was varied : a/w = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7. The notch-tip radius was fixed for all geometries and equal 0.25 mm. In contrast to a crack, it was found that the T-stress is not constant and depends on distance from the notch-tip. To estimate the T-stress in the case of a notch, a novel method, namely, method of line, inspired from the volumetric effective distance ahead of the notch tip. The effective distance corresponds to the point with a minimum of the stress gradient in the fracture process zone. Thus, the two-parameter approach was adopted for the notch two-parameter fracture mechanics in terms of the notch stress intensity factor Kpc and the effective (average) T-stress, Teff. Fracture toughness transferability curve (Kpc-Teff) of X52 pipe steels has been established. This approach was successfully used to quantify the constraints of notch-tip fields for various geometries and loading conditions. Moreoveer, the proposed T-stress estimation creates a basis to analyse the crack path under mixed mode loading from viewpoint of the two-parameter fracture mechanic

Approche globale à deux paramètres (K[rhô]-T[rhô]) (estimation des contraintes de confinements dans des structures portant des entailles)

L'importance de l'approche globale à deux paramètres dans l'analyse de mécanique linéaire élastique de la rupture est de plus en plus reconnue pour des évaluations de fracture dans des applications d'ingénierie. La considération du deuxième paramètre, à savoir la contrainte élastique T, ou T-stress en anglais, permet d'évaluer le niveau de confinement à la pointe de la fissure où d'entaille. Il est important de fournir des solutions de la contrainte T pour une pratique géométrie pour employer la mécanique de la rupture à base de contrainte de confinement. Dans la présente recherche, nous fournissant des solutions de la contrainte T pour une entaille en forme de U dans le cas de quatre éprouvettes : CT, DCB, SENT et Tuile Romaine. L'entaille en forme de U est analysée utilisant la méthode d'élément finie par le code de calcul Castem 2000 pour déterminer la distribution de contraintes à la pointe de l'entaille et le long du ligement. Le rapport du profondeur du défaut sur l'épaisseur a été varié : a/w = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 et 0.7. Le rayon de l'acuité de l'entaille a été fixé pour toute la géométrie à 0.25 mm. Contrairement aux fissures, il a été trouvé que la contrainte T n'est pas constante et dépend de la distance de la pointe de l'entaille. Pour évaluer cette contrainte dans le cas d'une entaille, une nouvelle méthode, à savoir, la méthode de ligne, inspirée de l'approche de méthode volumétrique proposée par pluvinage a été développée. La méthode est basée sur la détermination d'une contrainte moyenne T sur une distance effective en avant de la pointe de l'entaille. Ainsi, l'approche à deux paramètres a été adoptée pour la mécanique de la rupture à deux paramètres pour les entailles en termes du Facteur d'Intensité de Contraintes d'entaille Kpc et la contrainte moyenne (effective) Teff. La courbe de transférabilité de ténacité à la rupture (Kpc -Teff) dans l'acier de pipeline X52 a été établi. Cette approche a été utilisée avec succès pour évaluer quantitativement le champ des confinements à la pointe de l'entaille pour des différentes géométries et conditions de chargementsThe importance of the two-parameter approach in linear eleastic fracture mechanics analysis is increasingly being recognized for fracture assessments in engineering applications. The consideration of the second parameter, namely, the elastic T-stress, allows estimating the level of constraint at a crack or notch tip. It is important to provide T-stress solutions for practical geometries in order to employ the constraint-based fracture mechanics methodology. In the present research, T-stress solutions are provided for a U-shaped notch in the case of four specimens : CT, DCB, SENT and Romain Tile. The U-shaped notch is analyzed using the finite element method by the commercial Castem 2000 software to determine the stress distribution ahead of the notch tip. The notch aspect ratio was varied : a/w = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7. The notch-tip radius was fixed for all geometries and equal 0.25 mm. In contrast to a crack, it was found that the T-stress is not constant and depends on distance from the notch-tip. To estimate the T-stress in the case of a notch, a novel method, namely, method of line, inspired from the volumetric effective distance ahead of the notch tip. The effective distance corresponds to the point with a minimum of the stress gradient in the fracture process zone. Thus, the two-parameter approach was adopted for the notch two-parameter fracture mechanics in terms of the notch stress intensity factor Kpc and the effective (average) T-stress, Teff. Fracture toughness transferability curve (Kpc-Teff) of X52 pipe steels has been established. This approach was successfully used to quantify the constraints of notch-tip fields for various geometries and loading conditions. Moreoveer, the proposed T-stress estimation creates a basis to analyse the crack path under mixed mode loading from viewpoint of the two-parameter fracture mechanicsMETZ-SCD (574632105) / SudocSudocFranceF

Free vibration analysis of the structural integrity on the porous functionally graded plates using a novel Quasi-3D hyperbolic high order shear deformation theory

In this study, a novel quasi-three dimensional hyperbolic high-order shear deformation theory (quasi-3D HHSDT) is developed for free vibration analysis of porous functionally graded plates (FGPs). There are six unknowns in the current displacement field, and no shear correction factor is required. The mechanical properties are varied continuously through the thickness of porous FG plates using a modified power law function while considering the effect of porosities on the plate’s structural integrity. Two distinct porosity distribution models are considered, including even and uneven porosity distributions. The Navier technique is employed to obtain the closed-form solutions of motion's equations. An exhaustive parametric study is presented to show the influence of the different parameters on the fundamental frequencies

Assessment of cracked pipe by Monte Carlo method subject to transient flow

International audienceThe purpose of this works is to assess the risk of failure of cracked pipe due to fluid transient. A mathematical model has been established based on the mass and momentum conservation laws, the system of hyperbolic partial differential equations has been solved by the method of characteristics and a finite difference method to calculate the maximum pressure in the pipe. Afterwards, a finite element method have been used to perform a reliable assessment analysis of a cracked pipe used in water distribution by using Monte Carlo method and failure assessment diagram (FAD) tools to evaluate the safety factor from deterministic and probabilistic view points

Effect of gas tungsten arc welding parameters on the corrosion resistance and the residual stress of heat affected zone

International audienceThe Stress Corrosion Cracking (SCC) at weld joints is greatly defined by the input parameters used in the welding process. All the output parameters such as corrosion current, corrosion potential and residual stresses, etc., depend on the input welding parameters and define the quality of the welded joints. So, selecting the right parameters at optimum level satisfies the desired output. This paper presents an experimental design approach to study the welding process parameters effects on the stress corrosion at the Heat Affected Zone (HAZ). The experiments were performed using Gas Tungsten Arc Welding (GTAW) to join 304L austenitic stainless steel tubes using a standard 308L electrode. Three welding parameters were selected as input variables: Number of passes, gas flow (argon flow) and welding current. The main effects of the welding parameters were studied and the correlations between the different responses were established. The results showed that the passes number and welding current were the most significant parameters that control the welding process

Numerical study of semi-elliptical cracks in the critical position of pipe elbow

International audiencePipelines are considered as a major tool to transport hydrocarbons due to its important role in transporting fluids taking into account the operating conditions. Despite the importance of the elbow which considered as a critical part in the pipelines, the repeated failures and defects became a dangerous and enormously costly issue. In this numerical study, the Fluid-Structure Interaction (FSI) analysis was carried out using Ansys software. This work is divided into four main parts: the first part focused on studying and comparing the effect of bending radius of pipe elbow on the maximum of Von-Mises stress values for each radius with the yield stress of the steel of the pipe. The second part focused on the creation of a semi-elliptical crack for different locations along the elbow angles to show the critical position compared to the stress intensity factors. In the third part, the semi-elliptical crack angle orientation was studied at the critical position to estimate the critical angle. In the last part, the failure assessment diagram (FAD) was used to show the critical crack depth ratios at a critical position and a critical angle

Corrosion effect, constraint and path orientation estimated in cracked gas turbine blade

International audienceThe severe damage of gas turbine is due to the failure of the blade, in which the occurrence of a serious pitting occurred on the blade surfaces was evidence of fatigue marks in the fracture surface. This paper deals with the effect of semi-elliptical crack propagation on the crack path using a basic approach in predicting crack paths, namely, incremental methods. The crack position was chosen at the node coordinate where we have the maximum principal stresses. In this node, we have created a semi-elliptical crack and we have compared the results with the Stress Intensity Factors and T-stress values. The local fracture criterion of the maximum average tangential stress in the vicinity of fracture process zone including two terms of the Williams series solution for the mixed mode I/II loading has been used for predicting the angle of surface crack growth. The volumetric method (VM) for the compression-sensitive materials is described by a linear combination of the effective stress and the effective stress intensity factor. The results of our finite element computations based on a two-parameter fracture mechanics formulation showed that the T-stress has significant effects on the crack path