Numerical analysis of reinforced concrete beams pre cracked reinforced by composite materials

This work constitutes a contribution to the analysis of the behavior of beams reinforced by composite materials. The analysis was made by a study on concrete elements, and in pre-cracked reinforced concrete then reinforced with carbon fiber fabric bonded in tusi using an epoxy resin. In order to study the influence of the initial state of cracking, one of the beams was reinforced without it being pre-cracked and was compared to a pre-cracked and reinforced beam then to another loaded until rupture without being pre-cracked or reinforced and neither reinforced. the beams were pre-cracked and reinforced in their stretched part and on the lateral part with bands of different dimensions in order to avoid delamination on the one hand and to study the recovery of the composite under the effect of shearing and detachment on the other hand. However, the arrival of these structures brings new scientific problems and in particular the mode of rupture. The aim of this work is to increase the bearing capacity, reduce the deflection and limit the opening of cracks by ensuring better behavior of this element. The results obtained showed that the bonding of composite materials on reinforced concrete structures gave an increase in the ultimate breaking load and a reduction in deformations in concrete and steels. The results of this method coincide perfectly with those from the literature. The reinforcement allowed a significant increase in the breaking load and a reduction in the deflection at break up to 80%. The theoretical model based on the theory of modified reinforced concrete made it possible to predict with good precision the behavior in bending until the ultimate and it would be possible to use the fabric and the epoxy resin for the reinforcement in bending in building site, beams

Parametric Study Of Friction Stir Spot Welding (FSSW) For Polymer Materials Case Of High Density Polyethylene Sheets: Experimental And Numerical Study

Friction stir spot welding (FSSW) is a very important part of conventional friction stir welding (FSW) which can be a replacement for riveted assemblies and resistance spot welding. This technique provides high quality joints compared to conventional welding processes. Friction stir spot welding (FSSW) is a new technology adopted to join various types of metals such as titanium, aluminum, magnesium. It is also used for welding polymer materials which are difficult to weld by the conventional welding process. In various industrial applications, high density polyethylene (HDPE) becomes the most used material. The parameters and mechanical properties of the welds are the major problems in the welding processes. In this paper, we have presented a contribution in finite element modeling of the friction stir spot welding process (FSSW) using Abaqus as a finite element solver. The objective of this paper is to study the HDPE plates resistance of stir spot welding joints (FSSW). First, we show the experimental tests results of high-density polyethylene (HDPE) plates assembled by friction stir spot welding (FSSW). Three-dimensional numerical modeling by the finite element method makes it possible to determine the best representation of the weld joint for a good prediction of its behavior. Comparison of the results shows that there is a good agreement between the numerical modeling predictions and the experimental results

Finite element modeling and analytical solution of a semi-elliptic crack's Jintegral

In this work, we first evaluate the J-integral rupture parameter as a function of various crack parameters (crack size, rod dimensions, intensity and nature of loads) for various crack form. In a second step, and in the base of the results obtained by the finite element method, we propose formulas of the factor shape, whose implementation remains rather simple and inexpensive in terms of time, effort and means to the engineer in order to predict evolution of the rupture behavior of a cylindrical component with a semielliptical crack emerging from the surface. The comparison of the proposed analytical solution showed a good performance relatively with results of the literature

Effect of contact forces on fretting fatigue behavior of bolted plates: Numerical and experimental analysis

International audienceThis paper describes the effect of contact forces on the fretting fatigue behavior of bolted plates. Both fretting fatigue experiments and numerical simulation with FEM and SEM/EDS observations and analysis were carried out. With the increase of contact forces, the sites of crack initiation change from the edge of the central hole to close the border of contact and the fretting fatigue life increases. The local stresses and the relative displacement in the contact zone are two principal factors which influence the fretting fatigue behavior. A Map of Material Response (MMP) was determined basing on obtained results can describe the behavior of the fretting fatigue damage and predict the conditions which conduct to cracking initiation and propagation

TEMPERATURE PARAMETER EFFECT ON THE FRACTURE BEHAVIOR OF THE POLYMER MATERIAL: CASE OF HDPE

In this study, the finite element method is used to analyze the effect of a geometric discontinuity on the fracture behaviour of polymer material (High-Density-Polyethylene; HDPE). The effect of the temperature parameter on the distribution of stresses and strains at the notch (geometric discontinuity) has been studied. The results obtained numerically show a good correlation with experimental results. The Rice-Tracey (RT) model is used to reproduce the macroscopic mechanical behavior of the HDPE material in terms of stress versus strain for different temperature level

Effect of hardening induced by cold expansion on damage fatigue accumulation and life assessment of Aluminum alloy 6082 T6

Hole cold expansion (HCE) is an effective method to extend the fatigue life of mechanical structures. During cold expansion process compressive residual stresses around the expanded hole are generated. The enhancement of fatigue life and the crack initiation and growth behavior of a holed specimen were investigated by using the 6082 Aluminum alloy. The present study suggests a simple technical method for enhancement of fatigue life by a cold expansion hole of pre-cracked specimen. Fatigue damage accumulation of cold expanded hole in aluminum alloy which is widely used in transportation and in aeronautics was analyzed. Experimental tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. These tests were performed by using two and four blocks under uniaxial constant amplitude loading. The increasing and decreasing loading were carried. The experimental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the 'damaged stress model', which takes into account the loading history, yields a good estimation according to the experimental results. Moreover, the error is minimized in comparison to the Miner's model

Effect of the mechanical properties and mode loading on the mechanical behaviour of weldment: a numerical analysis

Welding is used to realize permanent assembly in mechanical structures to assure the continuity of the parts to be assembled contrary to the other assembly techniques which have physical or chemical discontinuities. Generally, crack evolution depends on several intrinsic and extrinsic parameters of material. The aim of this work is to analyse the severity of crack defects on the mechanical behaviour of Welded joints. The cracks are considered located in the weld metal. The J-integral method was used to analyse the fracture behaviour of these structures by the two-dimensional finite element method using Cast3M code. The effect of the mechanical properties, the mismatching and the crack size on the J-integral values was highlighted. A good correlation between the FEM simulations and the literature analysis results was observed. We note that the loading mode affects directly the J-integral value and consequently on the mechanical behaviour of the weldment