•A new phase field model for anisotropic material is proposed for the modeling of progressive failure of laminate.•The explicit relationship between the MPP and the critical energy release rate of ...fiber and matrix is obtained for the first time.•The proposed method is implemented into the commercial software Abaqus through UEL.•The method is extended for the modeling of variable stiffness lamina with curved fiber orientation.
A new phase method for predicting crack propagation path and mechanical response of fiber reinforced composite laminate is proposed. A new three-dimensional (3D) crack surface density function considering material anisotropy is proposed for composite laminates. The explicit relationship between the model penalty parameter (MPP) in a standard anisotropic phase field method and the material properties is solved analytically. This relationship is then used to construct a new expression of driving force in phase field model to account for longitudinal, transverse normal and transverse shear cracks in composite laminates. The proposed method is implemented into the commercial software ABAQUS through user subroutine user defined element (UEL). Numerical methods on both two-dimensional (2D) lamina and 3D angle ply laminate are provided. The present predictions are in good agreement with the experimental and other numerical results.
This study performed a nonlinear finite element analysis on an ultra-high performance fiber reinforced concrete (UHPFRC) one-way reinforced concrete slab with openings. This study contributes to a ...comprehensive understanding of the previously unstudied behavior of one-way UHPFRC slabs with slits of varying sizes and placements; additionally, a comprehensive comparison is made between the structural behavior of conventional concrete RC slabs and UHPFRC slabs. This study constructed and validated a finite element model (FEM) using the authors' experimental data. Ten models are included in this analysis: In this experimental investigation, the aperture widths and positions of the slabs are altered to determine their effect on the results. In the initial phase of this numerical investigation, a FEM was constructed, and its accuracy was validated against five experimental data, one of which is a closed-loop reference. ABAQUS was utilized for the analyses. Behavior under a total load, maximal load, and failure modes of the validated FEM using experimental data closely match those of the experiment. Due to the use of UHPFRC to reduce the impact of openings on load capacity, the finite element analysis results were very near to the test results, with an average error of 2.232%. Five specimens of UHPFRC were analyzed with finite elements using a validated analytical model and the results of load-displacement behaviors. The finite element method is ideal for investigating the nonlinear behavior of multi-perforated slabs due to its reliability and efficiency.
•A series of compression and tensile tests for UHPC and Normal strength concrete was carried out.•The module elasticity and average compression and tensile strength of the materials were evaluated.•A ...calibrated Finite Element model using Concrete Damage Plasticity (CDP) was developed to predict the behavior of the UHPC.•Experimental and numerical results were compared and the effects of the mesh sizes were discussed.
Ultra-High Performance Concrete (UHPC) is an advanced technology in concrete industry with superior characteristics such as high strength in compression and tension, ductility, and durability. This paper determines the tensile and compressive behavior of UHPC and a comparison is made with Normal Strength Concrete (NC) for the development of a numerical model to simulate the behavior of UHPC using the Finite Element (FE). The experimental tests including a cylinder and cube compressive test, flexural, briquette and splitting tension tests to evaluate the ultimate capacity of the material in compression and tension and its modulus of elasticity. The primary focus of this research, however, was to simulate material properties of UHPC through commercial FE software allowing the study of the structures including UHPC. The numerical analysis provides the mechanical properties of UHPC that can be used in FE software using Concrete Damage Plasticity model (CDP) to define ductal UHPC in the absence of sufficient experimental data. The numerical and the experimental results were generally in good agreement.
•The damage mechanism of the aluminum alloy caused by the stray light has been studied.•The transient and steady thermal direct coupling model of laser action process is established.•The temperature ...dependence of mechanical damage and ablation, surface roughness and optical parameters are considered.
The particle pollution caused by the stray light of the high-energy laser system irradiating the frame aluminum alloy is one of the most important reasons that hinder the stable operation of the system. Therefore, accurately revealing the mechanism of the interaction between the stray light and the aluminum alloy frame is an important and challenging task to ensure that inertial confinement fusion (ICF) system can generate clean and sustainable energy. In this paper, based on the secondary development of ABAQUS, a transient-stabilized thermal-mechanical direct coupling model is developed and experimentally investigated for the laser-material interaction in the high-energy nanosecond laser system with an energy density of 2 J/cm2. The mechanical damage, thermal ablation, and especially the temperature dependence of the thermal optical parameters of the aluminum alloy are considered in the modeling. Through comparative analysis, the results indicate that the effect of the variable optical properties must be considered in order to accurately reveal the mechanism of intense laser irradiation. On this basis, we found that the pulsed intense laser is absorbed by the aluminum alloy with a smaller absorption rate, after the aluminum alloy surface reaches the melting point and liquefies. This means more laser is reflected to the laser system, reducing the stability and reliability of the system. The whole process includes thermal expansion, thermal melting and potential mechanical damage, while no vaporization ablation occurs. The simulation conclusions are verified by the characterization of the experimental specimens, and it is verified that the diameter of the melting area is close to the full width at half maximum (FWHM) of the Gaussian laser source. This study provides a more accurate numerical model for precisely revealing the mechanism of high-energy nanosecond laser irradiation on metallic materials, and thus promoting the sustainable and reliable generation of clean energy from inertial confinement fusion.
Two of the most important of the loads exposed to the structures whose construction material is pultruded GFRP are buckling and vibration loads. Therefore, it is crucial to determine the behavior of ...this material against buckling and vibration loads considering the fiber and layer configurations. Pursuant to this goal, comprehensive experimental, numerical and analytical studies have been undertaken. An exact analytical solution based on first order shear deformation plate theory was used for the solution of stability and vibration problems. The virtual displacement principle was utilized herein to derive governing differential equations. Effective material properties of pultruded GFRP composites were obtained by using the mixture rule model. The laminated plate was assumed to be a plate strip in cylindrical bending. The solutions were obtained with an infinite series. On the other hand, a numerical study was conducted by a finite element software, ABAQUS. Burn-out and mechanical tests were performed to determine the mechanical properties of the obtained pultruded GFRP composite specimens. The buckling and modal analysis for natural frequencies tests were utilized to investigate the performance of pultruded GFRP specimens. The experimental findings were compared with the calculated analytical and numerical results, and good conformance was obtained. Macro and micro mechanical damage analyzes were performed to better understand the behavior of the pultruded GFRP composite specimens.
Cold drawn wires were produced by drawing the pearlitic wire rod (5.5 mm diameter). Cold drawing involved multiple stages to a final drawing strain of ≈ 2.5. The cold drawing alters the pearlite ...morphology. During the wire drawing, the change in morphology is location dependent. This will create the gradient in stain and strain mode between the surface and the center. This led to have a strain partition among ferrite and cementite phases. The strain partitioning plays a major role in the final tensile and torsional performance of the cod drawn wire. The present work dealt with the experimental and their numerical simulations of stress gradients and the role of pearlite morphology on tensile and torsional properties of the pearlitic steel wire.
•Superplastic behavior of near-alpha Titanium alloy (TA15) with equiaxed fine grain structure have been studied.•A wide range of thermal-mechanical tensile test performed at temperature range of ...880–40 °C and strain rates range of 5 × 10–4–10–2 s−1.•A mechanism based unified viscoplastic constitutive model is established.•The proposed constitute model is implemented in FE software to check its validity against the superplastic forming experimental test for the multi-box die.
Titanium alloy, TA15, has a high strength-to-weight ratio, high weldability, and superior creep resistance at high temperatures up to 550 °C. TA15 is difficult to deform, especially for forming complex-shaped large-scale web–rib components, due to its low plasticity, large inhomogeneous deformation and narrow processing window. The objective of this research is to model the superplastic mechanisms in TA15 alloy with equiaxed, fine grain structure, and applying the proposed constitutive model to investigate the maximum grid aspect ratio, that can be achieved in superplastic forming (SPF), for a TA15 sheet with an initial thickness of 1.2 mm. Thermo-mechanical tensile tests are conducted first to characterize the superplastic behavior of the material in the temperature range of 880– 940 °C and the strain-rate of 0.0005–0.01 s−1. A set of mechanism-based unified visco-plastic constitutive equations has been proposed and calibrated based on the results of stress-strain data. A gradient-based optimization method is applied for the calibration of constitutive equations. The constitutive model is incorporated into FEA code through creep subroutine to check the validity of the proposed material model against the experimental SPF test of a multi-box die. Predicted sheet thickness and thinning in a die entry radius region at the end of forming are examined in detail. Preliminary results show a good agreement between the computational and experimental results.
The commercial finite element (FE) code Abaqus is coupled with the deep neural network (DNN) model, namely Abaqus-DNN mechanics system, to learn the constitutive law of the fiber-reinforced ...composite. The proposed system enables data communication between Abaqus and DNN model, which leverages the versatile FE analysis ability of Abaqus and the powerful machine learning using DNN. Abaqus-DNN enables DNN to learn the constitutive law in a form-free manner. The learned result automatically satisfies the equilibrium and kinematics equations, which avoids inaccuracies associated with the presumed functions in the constitutive laws and guaranteed the learned constitutive law following the laws of physics. The Abaqus-DNN mechanics system was implemented to learn the full set of engineering constants of the constituents of a fiber-reinforced composite. Furthermore, the proposed system was applied to learn the progressive damage constitutive law of a fiber-reinforced composite laminate. The backward propagation equations of the neural network were modified to track the gradient of the loss function from Abaqus to DNN. The results show that Abaqus-DNN can accurately learn constitutive laws based on structural level data. This system provides a generalized approach for learning unknown physics inside a mechanics system by coupling neural network with commercial finite element codes.
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.
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