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Go to Editorial ManagerThis research concerns with the fracture behavior of reinforced concrete beams without shear reinforcement numerically. The software ABAQUS is adapted to simulate the crack propagation using the eXtended Finite Element Method (XFEM), taking into account materials nonlinearities using concrete damage plasticity CDP criteria. XFEM is used to solve the discontinuity problems in the simulation. The maximum principal stress failure criterion is selected for damage initiation, and an energy-based damage evolution law based on a model- independent fracture criterion is selected for damage propagation. The traditional nonlinear finite element analysis is used to specify the crack initiation position, which is required to specify the crack location in the analysis of beams using XFEM. Three-dimensional reinforced concrete beam models are investigated subjected to three and four-point loading tests. Simply supported beams under the effect of applied static load are investigated. An elastic perfectly plastic model is used for modeling the longitudinal steel bars. The main variables considered in the study are beam depth and the shear span with beam length. The numerical results are compared with the available experimental results to demonstrate the applicability of the model. The XFEM provides the capability to predict the concrete member fracture behavior.
Corrugated plates play very important role in various engineering applications. The occurrence of crack in the body of corrugated plate might results in catastrophic failure. In the present paper there are different profiles of corrugated plates (trapezoidal, sinusoidal and triangle) that are studied. In each profile the stress intensity factor and shape factor were calculated for various crack orientations, various corrugation angles and different curvature radius for the same profile. They are all subjected to different loading conditions using Extended Finite Element Method (XFEM). It is found the stress intensity factor when load applied parallel to corrugation direction is higher when load applied perpendicular to corrugation direction. Also found that the stress intensity factor increase by 115% when curvature radius increases with the load applied perpendicular to corrugation. This study also found and explained that the stress intensity factor increases slightly when the corrugation angle of triangle corrugated plate increases. In all cases studied, the trapezoidal corrugated plate shows the lower values of stress intensity factor compared to the sinusoidal and triangle corrugated plates.
The extended-finite element method (X-FEM) is used for crack analysis of orthotropic and isotropic functionally- graded composite material (FGCM) plate with slanted crack under thermal loadings. The enrichments functions of discontinuity are implemented. Mixed-mode SIFs are calculated in isotropic and orthotropic FGMs. Gaussian technique (Q4) has been applied in numerical calculation of interaction of solution. Thermal effects, fundamental equations, the interaction integral of non-homogeneous cases (M-integral), and proposal numerical integration rule are set to simulate and to debate the accuracy of the present work results in comparing with the results of the references that available in the literature. In addition, the effect of size of crack is studied to discuss the values of energy release rate and stress intensity factors with different crack angles. The present study is implemented by using MATLAB program to present steady state thermo XFEM fracture analysis of isotropic and an isotropic FG plate with inclined center crack.
Corrugated plates play an important role in many modern constructions applications. Being the main components like piles or stiffeners means they quite often subjected to high levels of stresses. The presence of flaw or crack in the structure of loaded corrugated plate may lead to the situation of crack growth and then catastrophic failure. Extended Finite Element Method is used to avoid remeshing during crack growth simulation. In order to characterize crack growth in corrugated plate two methods were used which are virtual crack closure method and cohesive segments method. Two case studies were investigated in this study. In the first case the material behavior is assumed to be linear elastic, while in the second one the material behavior is assume to be elastic-plastic. The results obtained using the two methods showed a very good agreement both in linear elastic and elastic plastic cases.
This paper presents the effect of fiber orientation angle on the stress intensity factor SIF for carbon epoxy composite plates with single-edge, center, and inclined cracks of varying lengths under tensile load. The stress intensity factor and shape factor were calculated individually for each case, with nine different fiber orientation angles computed using the extended finite element method XFEM concepts. It is found the stress intensity factor increases with increasing crack lengths while the shape factor decreases. In the case of single edge cracks, the SIF increases in the average value reached (173 %) for composite plates with different fiber orientation angles, while in the case of the center crack, the average value of SIF reaches (81 %). It was observed in this study that the increases in stress intensity factor and the decreases in the shape factor with different crack lengths were more stable in the composite plate with a fiber orientation angle of 75°. The higher values of SIF at an angle of 75° are because of the high probability of fiber slippage at 75° due to induced shear stresses in addition to the tensile stresses at the fiber-matrix interface. As a result, the crack tip has a high-stress intensity factor.
Due to the significance of structural sandwiches with hexagonal cores, utilized in various applications including aerospace, marine industries, and rail transport, and their design that imparts superior strength compared to conventional forms. In this paper, fracture behavior of these structural sandwiches was examined. Initially, the equivalent modulus of elasticity was empirically determined for many cell side lengths, utilizing the stress-strain relationship derived from tensile tests on hexagonal specimens. The fracture behavior was analyzed numerically using Abaqus software. The core and the complete sandwich structure were examined under various loads, including tensile and shear forces. The influence of the hexagonal cell dimensions on the fracture modules and the stress intensity factor (SIF), was assessed. It was observed that when the cell thickness remains constant while the side length varies, the SIF increases with the increasing in side length. This leads to the influence of stiffness, where it decreases with the increase in side length of the cell core. For instance, when the side length is 10, the stress intensity factor is 4.821, while when the side length is 20, the stress intensity factor becomes 22.35. A relationship was found between the stress intensity factor and thickness, similar to the tension case. However, here, a relationship between (kl) and the (a/tc) ratio was established.
Adhesives have been around for millennia. Nevertheless, this technique for joining has only seen significant development within the past 70 years. Professional technical engineering applications primarily use adhesives derived from synthetic polymers, a development that dates back to the mid-1940s. Its characteristics facilitate their strong adhesion to most substrates, as well as their ability to transfer substantial loads. This paper presents an extensive assessment of the current knowledge in the field of adhesives and related technologies, with a focus on adhesion theories and their parameters, as well as designing, joint configuration, geometric aspects, and failure modes. The paper also explores the interplay between research and development efforts, industrial standards, and regulatory aspects, with the goal of fostering collaboration between academia and industry. Over the past years, the development of new materials, methods, and models has resolved many of the shortcomings. Nonetheless, it is still possible to evaluate and estimate the optimal combination of aspects that will give the greatest efficiency and performance for adhesive bond joints (ABJs).
In this study, loading was carried out for several types of perforated plates, such as circular, rhombic and rectangular holes, where the holes were arranged in two types, namely straight arrangement and alternating arrangement. The stress intensity factor and shape factor were calculated for each case, taking into account the diameter of the holes. So, it is found the SIF increases significantly when the plate is perforated, and the same applies to the shape factor, also increases. In the case of circular holes, the increases in the average value of (SIF) reached to (80.88 %) when the plate was perforated with alternated arranged of circular holes, while the straight arrangement of circular holes the increases of average values of SIF reach to (67.55 %). Either in the case of rhombus holes: the SIF values are increases to (51.07 %) when the plate was perforated with the alternated arrangement, while in the straight arrangement of holes the (SIF) increase to (35.43 %). It was observed through this study, the increases of stress intensity factor and the shape factor with different crack lengths were more stable in the plate that perforated with an alternated arrangement of holes than the straight arrangement. The higher values of stress intensity factor obtained when the plates were perforated with circular holes, due to the circular shape has more stiffness, so the Absorption of force will be small Compared with the rhombus and rectangular shape that will be less stiffness which the absorption of strength is greater.