Numerical Analysis of Polymeric Thin Films Fracture Based on Energetic Approach "The Essential Work of Fracture"

Actually, polymeric materials are widely used in industry due to their attractive properties. These materials are replacing the traditional materials used to manufacture mechanical components. Thus, their mechanical behavior should be known for a better and judicious use of the material. Fracture mechanics principles and tools are used to characterize polymeric thin films fracture. In this paper a global energetic approach proposed to characterize the rupture phenomenon and determine the essential work of fracture

Determination of Stress Intensity Factor in Concrete Material Under Brazilian Disc and Three-Point Bending Tests Using Finite Element Method

Concrete is a brittle material with high compressive strength, low tensile strength and poor toughness, where cracks of different degrees and different forms can be developed, which compromises the durability and the lifetime of concrete structures. The crack starts to propagate in concrete when the crack tip stress intensity factor reaches the fracture toughness value (critical stress intensity factor KC or fracture energy GC). Many studies were carried out on the fracture of concrete to measure KC and GC based on LEFM (Linear Elastic Fracture Mechanics).This paper uses tow approaches to analyze the crack propagation of cracks three-point bending concrete beam and Brazilian disk with initial crack based on determination of stress intensity factor analytically starting from weight functions and numerically using the finite element software platform Abaqus

Fatigue Crack Propagation Under Variable Amplitude Loading Analyses Based on Plastic Energy Approach

Plasticity effects at the crack tip had been recognized as “motor” of crack propagation, the growth of cracks is related to the existence of a crack tip plastic zone, whose formation and intensification is accompanied by energy dissipation. In the actual state of knowledge fatigue crack propagation is modeled using crack closure concept. The fatigue crack growth behavior under constant amplitude and variable amplitude loading of the aluminum alloy 2024 T351 are analyzed using in terms energy parameters. In the case of VAL (variable amplitude loading) tests, the evolution of the hysteretic energy dissipated per block is shown similar with that observed under constant amplitude loading. A linear relationship between the crack growth rate and the hysteretic energy dissipated per block is obtained at high growth rates. For lower growth rates values, the relationship between crack growth rate and hysteretic energy dissipated per block can represented by a power law. In this paper, an analysis of fatigue crack propagation under variable amplitude loading based on energetic approach is proposed

Experimental and FE Modeling of Mixed-Mode Crack Initiation Angle in High Density Polyethylene

In this paper, an experimental and a numerical analysis were carried out using High density polyethylene (HDPE). Sheets with an initial central crack (CCT specimens) inclined with a given angle are investigated and compared to the loading direction. The kinking angle is experimentally predicted and numerically evaluated under mixed mode (I+II), as a function of the strain energy density (SED) around the crack-tip, using the Ansys Parametric Design Language (APDL).According to the experimental observations and numerical analysis, the plan of crack propagation is perpendicular to the loading direction. Moreover, as suggested by Sih in the framework of linear elastic fracture mechanics (LEFM), the minimum values Sminof the factor S are reached at the points corresponding to the crack propagation direction. These results suggest that the concept of the strain energy- density factor can be used as an indicator of the crack propagation direction

Numerical Study of the Mechanical Behavior and Fatigue in a Weld Bead by Friction Stir for a 6082-T6 Aluminum Alloy

The process of friction stir welding is a significant advance in the field of research on the Friction welding technique known for several decades. This assembly technique has obvious originality since welding is performed in the solid state, which can help eliminate birth defects related to solidification phase compared to conventional welding.The numerical modeling of this type of process is complex, not only in terms of the variety of physical phenomena which must be considered, but also because of the experimental procedure that must be followed in order to verify and validate numerical predictions. In this work, a finite element model is proposed in order to simulate the crack propagation under monotonic loading in different areas of the weld seam of a specimen CT-50 aluminum alloy 6082-T6.Microhardness tests were performed to characterize the Vickers hardness profile in the vicinity of the weld area. Friction stir welding process leads to a decrease of the static mechanical properties relatively to base material. Detailed examination revealed a hardness decrease in the thermo mechanically affected zone and the nugget zone average hardness was found to be significantly lower than the base alloy hardness. Welded specimens show significantly lower lives than base material

Analytical Study of Buckling of Hybrid Multilayer Plates

Thermal buckling behavior of hybrid multilayer plates was investigated in this paper. Different theories of plates taking into account or neglect the transverse shear are presented and the obtained results by these theories are compared. Nonlinear higher-order strain-displacement relations were considered. Using the principle of potential energy, the critical buckling temperatures are determined. Finally, a parametric study of the influence of various parameters such as: aspect ratios: b/a and a/h, thickness of metal, fiber angle and stacking sequence on the critical buckling temperature is shown and discussed. Numerical results indicate that the addition of metal to a composite material and the consideration of the transverse shear deformation have a significant effect on the thermal buckling behavior of simply supported hybrid multilayer plates

Modeling the damage of welded steel, using the GTN model

The aim of our work is the modeling of the damage in the weld metal according to the finite element method and the concepts of fracture mechanics based on local approaches using the code ABAQUS calculates. The use of the Gurson-Tvergaard-Needleman model axisymmetric specimens AE type to three different zones (Base metal, molten metal and heat affected Zone) with four levels of triaxiality (AE2, AE4, AE10 and AE80), we have used to model the behavior of damage to welded steel, which is described as being due to the growth and coalescence of cavities with high rates of triaxialit

Modeling the damage of welded steel, using the GTN model

The aim of our work is the modeling of the damage in the weld metal according to the finite element method and the concepts of fracture mechanics based on local approaches using the code ABAQUS calculates. The use of the Gurson-Tvergaard-Needleman model axisymmetric specimens AE type to three different zones (Base metal, molten metal and heat affected Zone) with four levels of triaxiality (AE2, AE4, AE10 and AE80), we have used to model the behavior of damage to welded steel, which is described as being due to the growth and coalescence of cavities with high rates of triaxialit

Admissibility of External Cracks in a Pipeline API X60 Using the SINTAP Procedure

In this paper we tried to apply the failure assessment diagram method on an API X60 pipeline under two pressures 70 and 90 bar, this work will be divided into two parts; the first part will be devoted to modeling and simulation of a pipeline under pressure 70/90 bar. With abaqus software to determine the stress intensity factor of several ratios, The second part will focus on the exploitation of these results in order to draw the diagram of evaluation of the failure (FAD), once finished, We can pronounce on the vulnerability of the cracks which can cause the ruin of the pipeline to study, on mode of ruin and proposed safety factors