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Go to Editorial ManagerThe principle aim of this research is concentrated to analyze the effect of cracks and their propagations on the mechanical behavior of a quasi-brittle material such as concrete. The singularity (stress concentration to infinity at the tip of crack) is avoided by using the principal of fracture energy with the fictitious crack approach. The concrete crack is divided into two major zones; the first one is the fracture zone (a combination of bridging effect and the cohesive microscopic cracking) which obeys a special law permitting the transmission of stress across the two faces of crack, this zone is considered as partially cracked concrete. When the opening of the crack exceeds a specific value, this zone is converted to a real crack (an open crack) and cannot transmit any stress across the two faces of a crack. The program of finite element used in this research is prepared by the researcher using discrete-crack approach with the experimental data obtained from the flexural test on notched beam loaded under three-point bending, where fracture mode I is dominated. The response of the applied load-crack mouth opening displacement (CMOD) with appropriate fracture energy is selected. The results show that the cohesive microscopic cracking zone for the plain concrete is very wide. The cohesive stress distributions across the microcracks with the corresponding crack openings are drawn from the first crack appearance till the beam failure.
Fracture mechanics approach is important for all mechanical and civil projects that might involve cracks in metallic materials the purpose of this paper is to determine a crack tip opening displacement fracture toughness experimentally, also study the effect of thickness on CTOD fracture toughness of low carbon steel and study the effect of Wire Electrical Discharge Machine (WEDM) to have a pre-crack, instead of fatigue pre-crack by using a CT specimen of low carbon steel with a thickness of (8,10, and15 mm), a width of 30mm, crack length of 15mm, and pre-crack of 1.3mm for all samples, this dimension according to ASTM-E399-13, by pulling the specimen in a 100 KN universal testing machine at a slow speed rate of 0.5 mm/min, the load applied on the specimen is generally a tension load. The crack tip plastically deforms until a critical point P C at this moment a crack is initiated. The computer-controlled universal testing machine gives the value of the load and the displacement transducer gives a crack mouth opening displacement. Critical crack tip opening displacement CTOD is found with the plastic hinge model (PHM) method. The result showed the stress intensity factor K I increases with increased loading in the elastic region and t he thickness effect refers to the effect of the plastic zone at the crack tip on the stress intensity factor, In a thin specimen, a plastic zone is large at the fracture tip leads to a high-stress intensity factor at the fracture tip but in the thick specimen, on the other hand, has a small a plastic zone and a low-stress intensity factor around the crack tip. The fracture toughness is found to increase with an increase in the thickness of specimens.
A two-dimensional finite element method for analysis and determination of second mode stress intensity factor (KII) of several crack configurations in plates under uniaxial compression is presented in this study. Various cases including diagonal crack (i.e. corner crack, central crack as well as at different locations on the diagonal) and central kinked crack are investigated with different crack's length, orientation and location. The influence of the contact between two crack surfaces is taken into account by applying contact element procedure with desired friction coefficient. The stress intensity factor is calculated by a crack surface displacement extrapolation technique. From the obtained results of the analysis it is found that, the corner cracked plates more dangerous than the other cracked plates, since it has the highest stress intensity factor. Also, the length and orientation of the kinked crack have significant effects on the stress intensity factor. The results of this investigation is illustrated graphically, exposing some novel knowledge about the stress intensity factor and its dependence on crack configuration.
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.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
New illustration for mixed mode fracture mechanics analysis of central cracked plates using crack extension technique and Matlab Environment is presented. The technique of crack extension is applied to the computation of mixed mode stress intensity factors in linear elastic fracture mechanics for these plates for different loads. The technique uses the Brown approximate solutions for stress intensity factors and the Westergaard analytical solutions for stress and displacement near a crack tip in finite plate to calculate crack extension during each load step using an proved to be a good tool for computation and results illustration for mixed mode stress intensity factors. The results were illustrated in a new form which is convenient for engineers and fracture mechanics analyst. The developed procedure reduced the need for sophisticated numerical analyses, which require more time and effort, to calculate the same parameters tackled in this research.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
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.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
The aim of the present paper is to investigate buckling phenomenon of various cracked plates under compression load. The finite element procedure (ANSYS Package) is used to determine the critical buckling load by considering the effects of crack length and crack location (i.e. crack parameters) as well as loading direction parallel or perpendicular with respect to crack faces. It is found from the obtained results which are summarized graphically in figures that the crack parameters and loading direction have significant effects on the critical buckling load (i.e. increased or decreased) of compressed cracked plates. The effects of these factors are discussed in detail. The useful and interesting conclusions drawn from this work will be helpful for health monitoring or condition assessment of aging plated structures with cracking damages.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
This paper deals with the computer simulation of stress distribution in a plane model of mild steel under biaxial tensile loading. The goal is to visualize the crack behavior under deferent ratios of biaxial loading through linear elastic fracture mechanics theory. A finite element method is considered in calculating the mixed mode of stress intensity factor that governing the influence of stresses distribution around the crack. Aspects of crack propagation are considered. It is found that the mw.imum ci..-cumfcrcnce .stress is not of the plane of crack but that inclined by an angle (68) from it.
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.
This paper studies and compared the fatigue crack propagation rate da/dN for three kinds of ceramic wheel (model A, model B, and model C) made of Si3N4 ceramic with different additives used for gas turbine application. The stress intensity factor range was calculated using finite element method and then compared with analytical approximate approaches. Experimental fatigue test was carried out on the three specimens taken from the models. As a result, the types of additives effect on fatigue crack propagation rate. The model A has the highest da/dN values and model C exhibits the lower values of da/dN.
The functionally graded beam is a wide field of research, which attracts great interest today in the field of engineering, science, and medicine society. This type of beam is made from functionally graded material that is characterized by several properties one of them is the high strength to weight ratio. In the current years, this beam has witnessed great developments in the mechanism of its composition and the materials used in its manufacture. This research provides an overview of the properties, types, advantages and challenges, and applications of the functionally graded materials. In addition, this paper review provides a summary of the analysis of bending and buckling that occurs on the functionally graded beam with and without crack effect from (2008-2021) year. Through this review, the following was noted: Firstly, a small number of researchers have worked experimentally, and the properties of a beam in most of the research are gradual towards thickness using the mixing rule. Secondly, the crack has a very severe effect on the behavior of both bending and buckling for the graded beam. This critical review can be considered a milestone in future analyzes of the graded beam and is also beneficial to designers and researchers working in this field.
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.
In this paper, a finite element method program under domain loading and plain strain conditions is developed and applied in evaluation of the stress intensity factor in opening mode (K1) in two dimensions crack problems. Two types of crack problems analyzed and verified: first, cracked rotating disc made from bi-directional fiber reinforced material composite, second crack blade made from bi-directional fiber reinforced metal matrix composite. It is found that the finite element method under domain loading is a good tool for the analysis of composite material. The simulation is accurate in comparison with that obtained from extrapolation method. The stress intensity factor for fiber reinforced metal matrix composite is larger when obtained from fiber-reinforced material under same condition.
This 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.
This work deals with the effect of using Recycled Concrete Aggregate (RCA) as a partial replacement of coarse aggregate in Self-Compacting Concrete (SCC), on the structural behavior (flexure and shear) of reinforced concrete one-way slabs. To the authors’ knowledge, this study is one of limited studies concerning the behavior of recycled aggregate concrete one-way slabs subjected to line loading with significant replacement of conventional aggregates by recycled concrete aggregate (up to 75 %). Three replacement ratios were considered: 25 %, 50 %, and 75 %. The mixes (with natural stone coarse aggregate, NCA) have an averaged compressive strength of ($F_{cu} = 42 \text{ MPa}$) at the age of 28 days with a tolerance of ($\pm 1.5 \text{ MPa}$). While, the mixes (with RCA) have an averaged compressive strength of ($38.5, 36.5, \text{ and } 34 \text{ MPa}$) for the three replacement ratios respectively, at the age of 28 days with a tolerance of ($\pm 2 \text{ MPa}$). All the slabs were cast with length of ($1600 \text{ mm}$), width of ($600 \text{ mm}$), while the thickness was variable. For this purpose, sixteen reinforced concrete one-way slabs were cast and divided into five groups (G1 to G5). Different parameters that affect the behavior of one-way slabs were studied and include type of failure, replacement ratios of NCA by RCA, amount of main reinforcement, thickness and locations of line loadings along the span. Hardened concrete specimens results show that the **compressive strength** $F_{cu}$, **tensile strength** $F_t$, **modulus of rupture** $F_r$, and **modulus of elasticity** $E$ were decreased as the RCA replacement increased. The experimental results of slabs show that the **ultimate capacity** of slabs decreased as the RCA replacement increased, the **deflection** and **strain** increase as the RCA replacement increases and the **crack width** increases as the RCA replacement increases. From the results of ultimate capacity, cracking load and moment, deflections, crack width and pattern and concrete surface strains, it can be concluded that the recycled concrete aggregate can be used as a partial replacement of natural coarse aggregate to produce self-compacting concrete mixes. Also, the behavior of one way slabs cast with SCC containing RCA is acceptable.
The objective of the present paper is to evaluate the effects of the soil-structure interaction on the seismic evaluation in the building when a framed building is supported on raft foundation. Also the foundation-soil interaction effect has been considered by replacing it with equivalent springs. Nonlinear static pushover analyses of eight-storey reinforced concrete hospital building located at Delhi-India has been performed using the Capacity Spectrum Method of ATC-40. The deformations define the state of damage in the structure through three limit states of the NEHRP Guidelines and the FEMA-356 have been used to evaluate the performance level of the building for drift, the plastic hinge stage of the crack and shear under the condition of the fixed base and the effect of the soil-structure interaction. The performance of the building and individual components has been estimated for Design Basis Earthquake and Maximum Considered Earthquake. The weight of the slab was distributed as triangular and trapezoidal loads to the surrounding beams as per IS 456:2000. The weight of the brick masonry was distributed uniformly on the beams. The results show that the soil structure interaction has marked effect on the roof displacement, storey drift, design base shear, effective damping and crack pattern for beams and columns while there is a minor effect on the torsional behavior of the building. The building is more critical in the performance level when considering the soil flexibility.
The discovery and identification of damages in engineering structures is very important in the field of engineering maintenance, as it is a great challenge in presenting new methods in measuring vibrations and discovering damages with the development in the field of automation and high accuracy in discovering damages. In this study, natural frequencies and mode shapes of transverse vibration for damage detection in structures are investigated. The study is performed for various crack depth and crack location. And suggested a new technique based on Continuous Wavelet Transform (CWT) and Convolution Neural Network (CNN). The comparison will be done by simulating the oscillations of a cantilever steel beam with and without defect as a numerical case. The proposed new technique proved to outperform classical methods and has achieved a100% accuracy in the identification of defect position for the data studied.
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 purpose of this paper is to determine a stress intensity factor experimental and numerically in the linear region by using a CT specimen of ductile material with a thickness of 15 mm, a width of 30 mm, and pre-crack 1.3 mm this dimension according to ASTM-E399-12 [1], by pulling the specimen in a 600 kN universal testing machine at a very slow speed rate of 0.5 mm/min. The load is applied until the fracture is accrued, the computer-controlled universal testing machine gives the value of the load and the displacement transducer gives a crack mouth opening displacement. The result showed experimental K I is equal to 75.412 MPa √ m, and numerical K I is equal to74.576 MPa √ m, this test showed a very slight decrease in FEA stress intensity factor compared to that in an experimental result which means the stress intensity factor, K I remains very close between experimental and numerical with an error percentage of about (1.12 %). The finite element analysis provides the best approximation to true fracture toughness values, and it can be used to acquire close parameters if experimental testing is not possible.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
This study investigates the shear strength behavior of two-layer reinforced concrete beams consisting of two different types of concrete. One of the layers made of lightweight concrete (LWC) and the other was normal weight concrete (NWC). A total of 16 shear deficient reinforced concrete beams were fabricated and cast with NWC, LWC, and two-layer beam of both material with different configuration. All the beams were tested under four-point loading after 28 days. The variables of the experimental program include the ratio of thickness of the lightweight concrete layer to the overall depth of beam ( h LW / h ), and concrete compressive strength. Experimental results which include load-deflection response curves along with failure modes for NWC, LWC and two-layer beams. The results showed that all beams failed in a similar mode, due to diagonal tension shear crack. Based on the experimental results it can be also concluded that the shear load is governed by compressive strength of lower layer of the concrete when the shear span to overall depth ( a / h ) of the beams is 2.75 or more. While for the a / h 2.375 and 2.00 the two-layer beam has a significant reduction in the shear capacity compared to the NWC beams and increasing compared to LWC beam. The ratio of experimental shear stress divided by the root square of concrete compressive strength (vexp √f c ' ) , which demonstrates the diagonally cracked concrete's ability to transfer strain and shear was maintained for all configurations greater than 0.17, which is the minimal value recommended by ACI318-19.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
The main objective of this study is to investigate the effect of repeated load on the strength and behavior of the spandrel beam by considering eight specimens divided into four groups based on the design methods; type of cross-section of the spandrel beam and the type of loading. Two design methods, two types of loading and two types of cross sel.1ions for spandrel beam are considered, the first is a solid rectangular section, while the other is a hollow rectangular section. The effect of repeated loads on the crack's width, deflections, torque, and angle of twist is studied using two stages of loading, the first stage is at the soft-cracking stage after the occurring of cracks in the spandrel beam and the second stage is the yielding of the bottom longitudinal reinforcement of the floor beam.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
This study investigates the effect of the shear span-to-effective depth ratio (a/d) on the behavior of high-strength steel fiber–reinforced concrete deep beams without stirrups containing circular web openings. A circular opening of 12.6 cm diameter was positioned at the center of the shear span, and beam performance was evaluated in terms of crack patterns, load–deflection response, and stress–strain behavior. Four specimens were tested experimentally. The control specimen consisted of a solid deep beam without openings and without steel fibers, while the remaining three specimens were reinforced with 1% steel fibers and included circular openings. All specimens were reinforced with 2Ø12 mm top bars, 3Ø16 mm bottom bars, and two stirrups at the supports to prevent local failure. The beams had different shear span ratios (a/d = 0.75, 1.0, and 1.5) and corresponding total lengths of 1025 mm, 1200 mm, and 1550 mm, respectively. All specimens were simply supported and subjected to two-point loading. The experimental results revealed that the optimal shear span ratio for maximum performance was a/d = 0.75 when combined with 1% steel fiber reinforcement. In addition, the ultimate strength of beams with circular openings decreased as a/d increased, with a strength increase of approximately 5.48% at a/d = 0.75 compared with a/d = 1.0.
In this investigation, the bond stresses between the reinforcement and concrete was studied by using non-material interface elements that are able to produce the bond stresses for the reinforced concrete beam gradually loaded from zero to failure. Depending on (Jawad) program, which is a non-linear analysis program of plain and reinforced concrete beams through a discrete-crack approach by using the finite element method. The stiffness matrix derivation of the interface element and the way of non-linear treatment were explained. The distribution of bond stress drawings along the steel reinforcement for different values of loading was achieved before and after cracking.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, Weibull uni-axial and multi-axial distribution function is applied to evaluate the reliability of the fracture strength of rotating turbine rotor wheel manufactured from ceramic material and have inner surface crack. Three cases are considered, first taking only the effect of rotational stresses, second taking the effect of rotational and thermal stresses in ceramic disc, and third taking the effect of rotational and thermal loading in ceramic blade. It was found that there is a convergence between results gotten from uni-axial and multi-axial distribution function, but multi-axial distribution function give small large in values result compared to uni-axial distribution function. The expected values of rupture strength of ceramic blade is higher than of that of disc material, therefore the failure occurs in blade first than in disc material in service survival.
This numerical study aimed to investigate the torsional behaviour of hollow cross section reinforced concrete members strengthened with steel fibers (end hooked and corrugated), subjected to pure torsion. The numerical results were compared with experimental results and show good agreement. The experimental study was conducted on ten steel fiber reinforced concrete specimens with low longitudinal reinforcement ratio to investigate the torsional behavior under pure torsion. For this analysis, a computer program (ANSYS 18.2) was used. The brick elements 8-nodes (SOLID65) were used to concrete simulation, while the steel bars simulated as axial members (link 180). The steel fibre was represented theoretically by the stress-strain relationship. The theoretical results indicated that the adopted smeared crack model is capable of making relatively acceptable estimations of cracking and ultimate torsional capacity of the members.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
A large number of RC structures or at least some of their members need strengthening or rehabilitation. Among the typical failure modes, the shear failure is more dangerous and less predictable, because of usually brittle behavior and sudden collapse. Therefore, there are necessities for upgrading the shear capacity and the local ductility of reinforced concrete beams. In this study, four different techniques of concrete jacketing were used to improve the behaviors of the shear deficiencies beams. The four techniques used in this study to enhance the behavior of the beams were by using a Self-Compacted Fiber Reinforced Concrete jacket without stirrups (S.-J. + Steel Fiber), a concrete jacket of Self Compacted Concrete with stirrups (S.-J. + Stirrups), a concrete jacket of ferrocement jacket (S.-J. + Ferrocement), and a concrete jacket of ferrocement jacket with external steel reinforcing bars (S.-J. + Ferrocement + R). These techniques contributed to enhancing the load-carrying capacity and delaying the appearance of the first crack in tested beams compared with the control beam by a percentage of (35, 59, 30, 6) % and (18, 35, 81, 80) %, respectively. The specimen (S.-J. + Stirrups) showed the best performance in comparison with the other used strengthening techniques used in this study in terms of stiffness and the ultimate load-carrying capacity. The ferrocement jacket (S.-J. + Ferrocement) was found to be the most suitable jacketing system used to enhance the shear capacity in terms of cracking load.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
The choice of aggregate type in producing reinforced concrete depends on the availability of the source sometimes and the intended concrete requirements like lightweight or normal aggregate concrete or high strength concrete. The punching shear resistance is being considered to be influenced by numbers of parameters including aggregate size and types. These parameters have not accounted in most of codes of design and have given a little attention by researchers. Most of available knowledge are based on outcomes from experimental works on beams. In this paper, the considerable slab tests without shear reinforcement are collected from literature in which aggregate types and sizes are given and they were failed in punching. The test results are compared to those calculated by ACI, EC2 and CSCT. The deficits of shear resistance are found clear where high compressive strength is combined with reinforcement ratio.