•A total of 18 SRAC and GRAC columns were fabricated.•Finite element analysis of all specimens was performed.•SRAC columns presented higher axial strengths.•A close agreement between FEA, ...theoretical, and experimental results was observed.
To develop a sustainable environment and to alleviate the problems of the large annual production of construction and demolition waste, the recycled aggregate concrete (RAC) has been used in the columns reinforced with glass fiber reinforced polymer (GFRP) bars. This study explores and compares the structural behavior of GFRP reinforced recycled aggregate concrete columns (GRAC columns) and steel bars reinforced recycled aggregate concrete columns (SRAC columns) under concentric and eccentric loadings. 18 circular concrete columns having a diameter of 250 mm and a height of 1150 mm were manufactured from which 9 samples consisted of GFRP reinforcement and the other 9 samples consisted of steel bars. The test measurements portrayed that the GRAC columns showed lower axial strength (up to 7.79%) with higher ductility indices (up to 4%) compared with SRAC columns. Both GRAC and SRAC columns showed similar failure modes and cracking patterns. Furthermore, both GRAC and SRAC columns presented significant reductions in the axial strength due to the loading eccentricities. The present study proposed a three-dimensional nonlinear finite element model (FEM) for predicting the structural response of GRAC and SRAC columns using ABAQUS 6.14. The simulation of RAC was carried out using a modified concrete damaged plasticity (CDP) model and that of GFRP bars was carried out using a linear elastic model. A theoretical model for predicting the axial strength of GRAC columns was given based on a large database of 270 GFRP reinforced concrete columns. The close agreements were observed among the experimental results, numerical simulations, and theoretical predictions for GRAC columns.
Multistable laminates have been widely analyzed in the recent past for their potential in morphing applications. However, all the analytical models developed up until now have taken into account only ...the free-free boundary condition. In this work two objectives are met: (a) an analytical model is developed, which extends the previously available models in literature to account for the cantilever boundary condition for a special class of hybrid bistable symmetric laminates (HBSL); (b) the previously proposed HBSL is modified by replacing the aluminum layers with bi-direction glass-epoxy prepregs in the layup. It is observed that the modified layup has a curvature similar to the previously proposed HBSL while maintaining bistability. The analytical model developed here successfully captures the equilibrium shapes and the snap-through behavior for this special class of laminates which is validated against the results obtained using ABAQUS® and experiments. The developed model is then subsequently used to study the design space and bistability characteristics of the HBSL and the proposed modified layup (m-HBSL) in the cantilever boundary condition.
The phase-field method is lately one of the most popular approaches for modelling of complex fracture phenomena. As known, the displacement field and phase-field variable cannot be determined ...simultaneously, except for easy problems, due to non-convexity of the energy functional. As a remedy, several staggered solution strategies have been proposed, where two PDE system is solved. Materials produced by powder metallurgy, such as sintered materials are increasingly in use. Compared to materials produced by traditional metallurgical production procedures, they possess exceptionally good vibration and noise reduction properties, and high rate of material utilisation. This makes this class of materials highly attractive for application in many fields of industry, especially for production of the complex geometry components. In this work, experimental investigation results performed on Astaloy Mo+0.2C, with density 6.5 g/cm3, will be used for validation of the phase field staggered algorithm. The proposed algorithm consists of two mesh layers (displacement- and phase field mesh layer), and it is implemented into FE software Abaqus via user subroutines UMAT and UEL. The numerical results obtained show good agreement to experimental testing.
In this work, the replacement of nickel and composite materials instead of metal vessels in the oil industry has been investigated. The modeling is based on finite elements, and the capabilities of ...Abaqus finite element software have been used to consider the vessel's behavior against lateral forces and hydrostatic forces. In this regard, considering the high resistance of this material, the stresses and displacements experienced by the vessel against various forces have been investigated. Also, the behavioral comparison between the vessel made of nickel and composite and the metal vessel in this research is of interest. The results show that this type of vessel has a high resistance to lateral forces and a high potential to resist various mechanical forces. Static stresses in vessel optimization have been reduced by using nickel material and 400 Psi composite. Also, it has been reduced by 750 psi and 1.5 in against the stresses of the lateral forces of the wind and the displacement of the vessel against the force of the earthquake. Finally, displacement against wind force is optimized by 3 in, which shows the proper performance of the vessel.
•A more practical approach for modelling microscopic progressive failure in 3D laminate is built.•Modeling detailed microscopic progressive failure mechanism in 3D laminate.•The failure mechanisms in ...composites at micro-scale are investigated from a 3D point of view.•An additional phase field is introduced to regularize the material properties with sudden change.•The significance of parallel computing in accelerating the modelling is demonstrated.
In this paper, the recently developed two-dimensional (2D) phase field model is further applied to study micromechanical progressive failure process in three-dimensional (3D) fiber-reinforced composites, exploring deeper insight into the intrinsic failure mechanisms caused by the sophisticated microstructures. Although more challenging, a 3D fiber-reinforced composite modelling is desired since it reveals more clearly physical progressive failure process than a 2D model. In this setting, a phase field model based modelling framework is thus adopted to capture the complicated progressive failure mechanisms in 3D composites, in particular, fiber/matrix interface debonding and kinking, matrix cracks propagation, and delamination between adjacent plies. All kinds of cracks are modelled based on cohesive zone model to obtain a more reliable prediction. This significant development of 3D analysis is a generalization of our previous 2D work, its implementation is however completely different as enhanced by parallel computing in terms of ABAQUS user-defined subroutine, which may target the real applications. Two new energy split schemes are proposed for the modelling of progressive damage in composite materials. Numerical verification and validation are given through the modelling of a unidirectional ply and of an angle ply laminate. The damage initiation, propagation, and interaction captured by the developed method are analyzed, exploring the complicated progressive failure mechanisms of fiber-reinforced composites.
There has been a great increase in the applications of micro thin-walled parts in many fields, such as medical devices, aerospace and so on. The requirement of machining dimensional accuracy for ...micro thin-walled parts is very high. Inconel 718has the advantages of high strength and corrosion resistance, which can meet the requirements of micro thin-walled parts under poor applying working conditions. However, it is difficult to machine. Micro-milling is a potentially effective processing technique for processing Inconel 718 thin-walled parts. Because of the low rigidity, deflection of Inconel 718 thin-walled parts is easy to occur in micro-milling process, which affects the machining accuracy. So far, the research on the deflection of micro-milling Inconel 718 thin-walled parts is still blank. In this paper, a method of deflection prediction of micro-milling thin-walled parts is proposed. Firstly, a simulation model of micro-milling Inconel 718 thin-walled parts process is established, which realizes the prediction of milling force. Then, by using element birth/death technique, a deflection prediction model of micro-milling thin-walled parts is built based on the predicted value of milling force output by the simulation model, which achieves the more efficient and accurate deflection prediction of micro-milling thin-walled parts. Finally, the correctness of the built simulation model of micro-milling thin-walled parts process as well as the deflection prediction model of micro-milling thin-walled parts are verified by experiments. The research provides a feasible way for deflection prediction of micro-milling thin-walled parts, and lays foundation for deflection suppression and machining accuracy improvement of micro-milling thin-walled parts to a certain extent.
Corrosion is a major factor responsible for failures and leaks in gas pipelines. In the context of external corrosion, the internal pressure within pipes can create stress and strain concentrations ...in the area affected by corrosion. These phenomena, combined with the presence of cavities or cracks resulting from the corrosion process, amplify the risk of pipeline failure. As corrosion reduces the wall thickness of the pipe, its ability to withstand internal pressures decreases significantly. Consequently, a pipe affected by corrosion may collapse at a much lower pressure compared to a pipe that has not been subjected to corrosion.
With a view to analyse and anticipate the behaviour of corroded pipes, finite element modelling is used, implemented through the Abaqus software. This tool allows for simulating the mechanical effects of internal pressure on the gas pipeline structure, thereby providing the ability to predict the pipeline's behaviour under various pressure conditions. This approach aids in identifying and assessing risks associated with corrosion, facilitating the implementation of suitable preventive and maintenance measures to ensure the integrity and functionality of gas pipelines.
•A three-dimensionally mesoscale concrete was geometrically reconstructed to reflect its heterogeneity.•A mesoscale model for sulfate-induced evolution of chemo-mechanical behavior of concrete was ...developed.•Chemo-mechanical response of concrete from sulfate diffusion to damage failure was numerically simulated.
This paper aims at numerical description on the time-varying chemo-mechanical behavior of concrete served in sulfate-rich environments. For this purpose, a three-dimensionally (3-D) mesoscale model was developed to investigate the chemo-mechanical damage evolution of concrete under external sulfate attack (ESA). Firstly, a geometrical reconstruction of 3-D concrete at meso scale was carried out to reflect its material heterogeneity, while the mechanical property of every composition in mesoscale concrete was quantitatively characterized; Secondly, the diffusion and reaction of sulfates in concrete were modelled, while its induced expansion deformation and damage evolution of CM matrix were formulated; Finally, by numerical implementation in ABAQUS, these developed models were used to numerically simulate the space–time distributions of sulfate and ettringite concentrations, expansive deformation, cracking damage, mechanical performance and failure mode of concrete, and results from numerical simulation were consistent with the experimental observations. Consequently, the developed model can describe time-varying chemo-mechanical behavior of concrete, and it is beneficial for the performance evaluation and life prediction of concrete structures in sulfate environments.
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•The most of parameters related to reinforced concrete have no effect on the capacity.•The most effective parameter for the capacity of the purlin is CFRP ply orientation.•±45° fiber ...orientation is recommended to prevent or delay shear damage.•Material properties of CFRP significantly affect the capacity of the purlin.•The number of CFRP plies should be selected carefully to avoid unnecessary use.
Dapped end prefabricated concrete purlins (PCPs) suffer from shear damages due to coating, snow, wind load and also their dead loads. In this present study, a series of numerical modelling is performed with the aid of finite element program ABAQUS in order to investigate this behavior of PCPs through parametric study. In addition to the mechanical properties of the PCPs, the strengthening of the PCPs with the help of carbon fiber reinforced polymers (CFRP) is considered as a parameter in the models. Pursuant to this aim, longitudinal steel reinforcement ratio, shear friction reinforcement ratio, bending reinforcement ratio, suspension reinforcement ratio, concrete and steel mechanical properties, pre-stressing level, CFRP ply orientation, the number of CFRP plies and material properties of CFRP composite were selected as the parameters. First of all, numerical models were verified using experimental test data of three PCP test specimens and five CFRP coupon tests. Later, a total of 50 different numerical models was created to investigate the behavior of PCPs thoroughly. Vertical load- displacements curves are compared and explained in detail. The result of the parametric study revealed that the effects of the parameters related to reinforced concrete except longitudinal reinforcement and material properties of concrete are very limited when compared to the effects of the parameters related to CFRP. The effect of FRP ply orientation is the most effective parameter that increases significantly the shear capacity of PCPs. More importantly is the general FRP layout is proposed to delay or prevent shear cracks for the beams and the proposed layout is proved through numerical analyses. ±45° fiber orientation is recommended to use to prevent shear damage.
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