Italian Group Fracture (IGF): E-Journals / Gruppo Italiano Frattura
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Object-Oriented Software for Fitness-For-Service Assessment of Cracked Cylinder Based on API RP 579
Get PDFFitness-for-service assessment of a cracked component intends to evaluate its remaining strength and remaining life to support the implementation of a maintenance plan. This research aims to develop a fitness-for-service assessment software to facilitate the task. The software development process included identifying the software specifications, designing the software structure, manipulating the information from the standard for programming, the graphical user interface design, and finally verification of the software. The assessment procedure employed in this study was the third edition of the standard API RP 579. The software structure was designed using an object-oriented concept. The software can perform integrity assessment levels 1, 2, and 3 option B, leak-before-break assessment, and remaining life assessment for a cracked cylinder that has a through-thickness crack or semi-elliptical surface crack oriented in an axial or circumferential direction. The applied loads could be a nominal axial force, bending moment, and internal pressure, as well as stress profiles perpendicular to the crack plane due to mechanical, thermal, and residual stresses. Accuracy of the software was demonstrated by applying it to example problems. Some aspects of the software extensibility were conceptually discussed
Effect of concrete cover thickness and main reinforcement ratio on flexural behavior of RC beams strengthened by NSM-GFRP bars
Get PDFExperimental and numerical programs were invoked to investigate the effect of concrete cover and area of main steel reinforcement on the flexural behavior of strengthened RC beams by near-surface mounted glass fiber reinforced polymeric (NSM GFRP) bars of different lengths. Nine beams divided into three main groups were tested under four-point bending. The three beams of the first group were strengthened by different lengths of GFRP bars and having a concrete cover of 50 mm, while the three beams in the second group were strengthened in a similar manner as those of the first group but the concrete cover was 30 mm. The main steel reinforcement in the first and second groups was 2Ø10. The three beams of the third group were similar to those of the first and second group but the main steel reinforcement was 2Ø16. The 3-D FE commercial ANSYS program was used for the numerical work. The experimental results showed that decreasing the concrete cover increased the flexural capacity of the strengthened RC beams but this improvement disappeared by decreasing the NSM GFRP bar length. The RC beams flexural strength increased with increasing area of main steel reinforcement. The numerical results showed an agreement with the experimental results
Modeling of CFRP strengthened RC beams using the SNSM technique, proposed as an alternative to NSM and EBR techniques
Get PDFIn this paper, an analytical and numerical study in FEM finite element by the ABAQUS software was conducted. Which aims to study the behaviour of RC beams bending strengthened with SNSM side near surface mounted technique, proposed as a solution to avoid the failure mode by debonding of the strengthening, the disadvantage of the EBR externally bonded reinforced technique, and the failure mode by separation of the concrete cover relative to the NSM near surface mounted technique, by comparing the behaviour of the three techniques, the effect of the quantity of strengthening and confirm the results with the literature. The results of this study show that the numerical and analytical model can predict the behaviour of strengthened RC beams according to the three techniques, a clear improvement of the bending capacity of beams strengthened is noticed. A good preservation of the ductility of SNSM beams with a better failure mode
Effect of Stiffener Characteristics on the Seismic Behavior and Fracture Tendency of Steel Shear Walls
Get PDFThe steel plate shear walls (SPSW) are currently being considered as a lateral load resisting system. A numerical method was proposed to have a comprehensive comparison of seismic behaviors of the plane wall (PW) and stiffened plane wall (SPW) with different stiffener characteristics, having the same weight, by using finite element modeling (FEM). The model was validated by using previously published experimental works. The material and geometric nonlinearity were taken into consideration. In this paper, the effect of using stiffeners with different cross-section shapes and directions will be studied, and key issues, such as load-carrying capacity, stiffness, and energy dissipation capacity, were discussed in depth. It was found that the proposed SPW with horizontal L, T, and U stiffeners could effectively improve load-carrying capacity by about 4, 20, and 23%, respectively. Diagonally and horizontally, SPWs with U stiffeners have higher energy-dissipation capacity than PW by about 57, 50%, respectively. This method provides a combination of high-performance stiffeners form and material for improving the seismic behavior of SPW
A closed form for the Stress Intensity Factor of a small embedded square-like flaw
Get PDFIn the present work, the stress intensity factor (SIF) of a small embedded square-like flaw is calculated by means of a procedure based on the Oore-Burns integral. An explicit equation is given to evaluate the SIF along the two axes of symmetry that correspond to the points where the SIF takes its maximum and minimum value on the contour crack. The SIF is calculated in accordance with FE numerical results
Alternative Estimation of Effective Young’s Modulus for Lightweight Aggregate Concrete LWAC
Get PDFThe prediction of effective mechanical properties of composite materials using analytical models is of significant practical interest in situations in which tests are impossible, difficult, or costly. Many experimental and numerical works are attempting to predict the elastic properties of Lightweight Aggregate Concrete (LWAC). In order to choose the optimized prediction composite model, the purpose of this paper is to appraise the effective Young’s modulus of LWAC using two-phase composite models. To this effect, results of previous experimental research have used as a platform, upon which, 07 two-phase composite models were applied. The outcomes of this comparative analysis show that not all two-phase analytical models can be directly used for predicting Young’s modulus of LWAC. The Hashin-Hansen and Counto2 models are in close concordance with the experimental Young’s modulus of all LWAC used for comparison in this study. Thus, the precision of this prediction model demonstrates its effectiveness and potential application as a model for Lightweight Aggregate Concrete. They were found more appropriate for reasonable prediction of elasticity modules of the LWAC
Experimental and numerical optimization study of shock wave damping in aluminum panel sandwich
Get PDFSandwich panels with polymer composite and light core composites are widely used in aircraft and spacecraft, vessels, trains, submarines, and cars. Due to their high strength to weight ratio, high stability, and high corrosion resistance, these structures have become particularly important in the industry. Reduction in impact energy, shock waves, and noise in many industries, including the automotive and military industries. Porous materials have always been the focus of attention due to their shock-reducing effects in various protective applications. For this reason, the study of physics governing shock propagation problems in porous media is of particular importance, and the complexity of the governing equations also results in the numerical solution of these equations with many computational problems and costs. In this paper, shock wave damping is investigated numerically and experimentally in aluminum blocks with porous grains scattered inside aluminum. The deformations of the specimens in numerical simulation and experimental testing have been compared. The results show that this material behaves similarly to the aluminum foam in both static loadings (practical pressure testing) and dynamic loading (explosion simulation) results, again similar to aluminum foam
Influence of contact parameters in fretting-fatigue contact 3D problems
Get PDFA numerical study on the influence of contact parameters on fretting fatigue behavior is carried out by using a new method SFEM (Stretching Finite Element Method) is presented in this article. Several parameters are made to vary: geometric shapes of the mesh, materials and contact parameters. The three-dimensional parametric model is composed by specimen and a pad in full contact. A Fortran Code is used to generate the parametric mesh. The stress intensity factors are calculated by varying the above contact parameters and the stress intensity factor under modes I, II and III are computed.
Numerical and analytical simulation of ballistic projectile penetration due to high velocity impact on ceramic target
Get PDFSimulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and High performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for penetration simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relationships indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0º,15º,30º,45º by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them
Tension Strength Prediction of Transverse Branch Plate-to-Rectangular Joint with Concrete Filling
Get PDFThis paper predicts the tension strength of Concrete-filled Branch Plate-to-Rectangular Hollow (CBPRH) joint by conducting experimental and theoretical analysis. A total of 46 X-joints with different geometric parameters were investigated, in which 4 specimens were tested under ultimate tension and 42 specimens were numerically analyzed. The joint’s strength, failure mode and load-displacement curve were obtained. Perfobond Leister Rib (PBR) was welded in part of the specimens to investigate its effect on joint’s tensile performance. It is shown that the ultimate strength of transverse CBPRH joint benefit from grouting of chord and installation of PBR. The ultimate strength of CBPRH joint with PBR is larger than the counterpart without PBR. Tension strength equations were proposed for both CBPRH joints with and without PBR by nonlinear regression. The chord axial stress reduction factor was discussed and a modified equation originated from hollow joint was recommended for CBPRH joint. Connection efficiency was presented and compared among branch plate-to-rectangular hollow (BPRH) joint, CBPRH joint and CBPRH joint with PBR