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1
Hu, Jing, Xiao Xing Li, Kwan Soo Chung e Rao Yao. "Spring-Back Evaluation of Stretch Bending Process Based on Chaboche Combined Isotropic-Kinematic Hardening Laws". Advanced Materials Research 204-210 (febbraio 2011): 1745–50. http://dx.doi.org/10.4028/www.scientific.net/amr.204-210.1745.
Testo completoAbstract (sommario):
We present a study on spring-back prediction in the stretching bending process using the Chaboche model combined isotropic-kinematic hardening law and Mises yielding criterion, and a material user subroutine (VUMAT, UMAT) program was developed base on the ABAQUS interface for the model. The effects of different hardening law on the spring-back in the stretch forming process was also analyzed and compared. The simulation results show that the combined isotropic-kinematic hardening law has the better spring-back prediction compared with the pure isotropic and kinematic hardening law in the stretch forming process, which is verified by the experimental results.
2
Belova, O. N., D. V. Chapliy e L. V. Stepanova. "APPLICATION OF THE UMAT SUBROUTINE FOR SOLVING CONTINUUM MECHANICS PROBLEMS (OVERVIEW)". Vestnik of Samara University. Natural Science Series 27, n. 3 (8 luglio 2022): 46–73. http://dx.doi.org/10.18287/2541-7525-2021-27-3-46-73.
Testo completoAbstract (sommario):
This paper presents an overview of the application of the UMAT subroutine of the SIMULIA Abaqus multifunctional software package in solid mechanics and related areas. This subroutine is used to describe new user materials that are not available in the class of standard materials of the SIMULIA Abaqus package. This overview article provides examples of problems and constitutive equations of materials that are modeled using UMAT / VUMAT procedures. Various types of materials are presented, successfully described by means of user-defined UMAT and VUMAT procedures. A general description and experience of using the UMAT subroutine is given. The results of finite element modeling of the deformation of aplate weakened by a central circular hole under uniform and uniaxial tension with steady-state creep in a damaged medium evolving according to a power law are presented in the coupled formulation of the problem (creep - damage). The distributions of stresses, strains, and damage fields at the tip of the defect under creep conditions are found, and an analysis is made of the effect of the damage accumulation process on the stress fields at the crack tip under steady-state creep conditions. The distributions of stresses and creep strains are demonstrated taking into account the accumulation of damage over time.
3
Ming, Lu, e Olivier Pantalé. "An efficient and robust VUMAT implementation of elastoplastic constitutive laws in Abaqus/Explicit finite element code". Mechanics & Industry 19, n. 3 (2018): 308. http://dx.doi.org/10.1051/meca/2018021.
Testo completoAbstract (sommario):
This paper describes the development of an efficient and robust numerical algorithm for the implementation of elastoplastic constitutive laws in the commercial non-linear finite element software Abaqus/Explicit through a VUMAT FORTRAN subroutine. In the present paper, while the Abaqus/Explicit uses an explicit time integration scheme, the implicit radial return mapping algorithm is used to compute the plastic strain, the plastic strain rate and the temperature at the end of each increment instead of the widely used forward Euler approach. This more complex process allows us to obtain more precise results with only a slight increase of the total computational time. Corrector term of the radial return scheme is obtained through the implementation of a safe and robust Newton–Raphson algorithm able to converge even when the piecewise defined hardening curve is not derivable everywhere. The complete method of how to implement a user-defined elastoplastic material model using the radial return mapping integration scheme is presented in details with the application to the widely used Johnson–Cook constitutive law. Five benchmark tests including one element tests, necking of a circular bar and 2D and 3D Taylor impact tests show the efficiency and robustness of the proposed algorithm and confirm the improved efficiency in terms of precision, stability and solution CPU time. Finally, three alternative constitutive laws (the TANH, modified TANH and Bäker laws) are presented, implemented through our VUMAT routine and tested.
4
Zhao, Pengjing, Jingpin Jiao, Gang Fang, Zhanghua Chen e Xiang Gao. "Investigation on tensile deformation and failure for 5052 aluminum alloy based on continuum damage model". Journal of Physics: Conference Series 2085, n. 1 (1 novembre 2021): 012039. http://dx.doi.org/10.1088/1742-6596/2085/1/012039.
Testo completoAbstract (sommario):
Abstract A VUMAT user material subroutine for the Lemaitre continuous damage mechanics model was developed based on the finite element solver ABAQUS/Explicit platform to investigate the deformation and failure behavior of 5052 aluminum alloy. The mechanical property parameters and damage parameters of 5052 aluminum alloy were identified by the inversion method combining tensile test and finite element simulation. The numerical simulation results showed that the force-displacement curves predicted by the established damage model were in good agreement with the experimental measurement, and the fracture location was close to the experimental results, which verified the accuracy and effectiveness of the damage parameters. The growth and distribution law of damage variable could be intuitively represented by the simulation results by the Lemaitre damage model.
5
Lian, J., M. Sharaf, F. Archie e S. Münstermann. "A hybrid approach for modelling of plasticity and failure behaviour of advanced high-strength steel sheets". International Journal of Damage Mechanics 22, n. 2 (27 marzo 2012): 188–218. http://dx.doi.org/10.1177/1056789512439319.
Testo completoAbstract (sommario):
The ductile damage mechanisms dominating in modern high-strength steels have emphasised the significance of the onset of damage and the subsequent damage evolution in sheet metal forming processes. This paper contributes to the modelling of the plasticity and ductile damage behaviour of a dual-phase steel sheet by proposing a new damage mechanics approach derived from the combination of different types of damage models. It addresses the influence of stress state on the plasticity behaviour and onset of damage of materials, and quantifies the microstructure degradation using a dissipation-energy-based damage evolution law. The model is implemented into ABAQUS/Explicit by means of a user material subroutine (VUMAT) and applied to the subsequent numerical simulations. A hybrid experimental and numerical approach is employed to calibrate the material parameters, and the detailed program is demonstrated. The calibrated parameters and the model are then verified by experiments at different levels, and a good agreement between the experimental and numerical results is achieved.
6
Gao, Wei, Zhiqiang Yu, Aijie Ma e Zhangxin Guo. "Numerical simulation of composite grid sandwich structure under low-velocity impact". Science and Engineering of Composite Materials 29, n. 1 (1 gennaio 2022): 516–28. http://dx.doi.org/10.1515/secm-2022-0176.
Testo completoAbstract (sommario):
Abstract The low-velocity impact finite element model of the carbon fiber-reinforced composite grid sandwich structure was established by ABAQUS. Its panels and grid are both carbon fiber-reinforced composite laminates. The constitutive relation of composite laminates is written into the VUMAT user subroutine using the Fortran language. Simulation of intralaminar failure behavior of composite laminates using the three-dimensional Hashin failure criterion. The quadratic stress criterion and the B-K energy criterion were used to simulate the interlaminar failure behavior, and the delamination damage of the composite panel and the interface debonding damage were simulated. The finite element models of four different types of composite grid sandwich structures, including quadrilateral configuration, triangular configuration, mixed configuration, and diamond configuration, were established. The influence of the single grid width and the height of the grid on the impact resistance of each composite grid configuration was studied. Compared with other geometric configurations, triangular grid sandwich structure provides the best energy absorption characteristics, and T-6-10 has the highest fracture absorption energy (15816.46 mJ). The damage propagation law of carbon fiber-reinforced composite grid sandwich structure under impact load is analyzed.
7
Bandaru, Aswani Kumar, e Suhail Ahmad. "Effect of Projectile Geometry on the Deformation Behavior of Kevlar Composite Armors Under Ballistic Impact". International Journal of Applied Mechanics 07, n. 03 (giugno 2015): 1550039. http://dx.doi.org/10.1142/s1758825115500398.
Testo completoAbstract (sommario):
A failure model based on the three-dimensional strains in a composite layer with improved progressive damage modeling has been implemented to predict the deformation behavior of composite armors subjected to ballistic impact. The present model comprises mainly of two parts. First, quadratic strain based failure criteria are presented to predict the initiation of failure modes. Second, the post damage softening behavior and degradation of the material stiffness is measured by damage evolution law. The model has been implemented within ABAQUS/Explicit as a user defined subroutine VUMAT. The validity of the model has been carried out by performing computational analysis of different composite armor materials such as Kevlar 29 and Kevlar 129 impacting with cylindrical-hemispherical nosed and 120° conical projectiles. It transpires that the predictions from the present model are in good agreement with the experimental and numerical observations available in the literature in terms of back face signature (BFS) for both the targets and projectiles. Further, the model has been implemented to study the effect of projectile geometry on the velocity time histories of the projectile, residual velocity and ballistic limit velocity. BFS values showed good agreement for conical projectile while for hemispherical projectile it is slightly low. The combination of Kevlar 129 armor and hemispherical projectile shows higher ballistic limit compared to that of the other combinations.
8
Al-Azzawi, Ahmad SM, Luiz F. Kawashita e Carol A. Featherston. "Predicting interlaminar damage behaviour of fibre-metal laminates containing adhesive joints under bending loads". Journal of Reinforced Plastics and Composites 41, n. 5-6 (17 novembre 2021): 167–86. http://dx.doi.org/10.1177/07316844211051706.
Testo completoAbstract (sommario):
This study includes experimental and numerical investigations on fibre-metal laminate structures containing adhesive joints under static bending loads. Experimental tests were carried out on Glare® 4B specimens manufactured in-house and containing doubler joint features. Numerical analyses were performed using Abaqus software including damage in the glass fibre reinforced polymer layers, ductile damage in the resin pockets (FM94 epoxy) and plasticity in the metal layers. A new cohesive zone model coupling friction and interfacial shear under through-thickness compressive stress has been developed to simulate delamination initiation and growth at the metal/fibre interfaces with the adhesive joint under flexural loading. This model is implemented through a user-defined VUMAT subroutine in the Abaqus/Explicit software and includes two main approaches, firstly, combining friction and interfacial shear stresses created in the interlaminar layers of the fibre-metal laminate as a result of through-thickness stresses and secondly, considering elastic-plastic damage behaviour using a new cohesive zone model based on the trapezoidal law (which provides more accurate results for the simulation of toughened epoxy matrices than the commonly used bilinear cohesive zone model). Numerical results have been validated against experimental data from 4-point bending tests and a good correlation observed with respect to both crack initiation and evolution. Delamination and shear failure were noted to be the predominant failure modes under bending stresses as expected. This is due to the higher mode-II stresses introduced during bending which cause different damage evolution behaviour to that seen for axial stresses. Finite element results revealed that both friction and shear strength parameters generated from through-thickness compression stresses have a significant effect in predicting damage in fibre-metal laminate structures under this type of loading.
9
Chaouki, Hicham, Stéphane Thibodeau, Mario Fafard, Donald Ziegler e Houshang Alamdari. "Characterization of the Hot Anode Paste Compaction Process: A Computational and Experimental Study". Materials 12, n. 5 (8 marzo 2019): 800. http://dx.doi.org/10.3390/ma12050800.
Testo completoAbstract (sommario):
The aim of this work is to model and characterize green anode paste compaction behavior. For this purpose, a nonlinear viscoplastic constitutive law for compressible materials, based on the finite strain theory and the thermodynamic framework, was used. An experimental study was carried out to characterize axial and radial behaviors of the anode paste. To this end, simple compaction tests using a thin steel instrumented mold were performed at a temperature of 150 °C. Results of these experiments brought out the nonlinear mechanical behavior of the anode paste. Furthermore, they showed the importance of its radial behavior. The constitutive law was implemented in Abaqus software through the user’s material subroutine VUMAT for explicit dynamic analysis. An inverse analysis procedure for material parameters identification showed that the model predicts compaction tests results with a good agreement. In order to assess the constitutive law predictive potential in situations involving density gradients, compaction tests using complex geometries such as slots and stub holes were carried out. Finite element simulation results showed the ability of the model to successfully predict density profiles measured by the X-ray tomography.
10
Zhang, Yanfeng, Zhengong Zhou e Zhiyong Tan. "Compression Shear Properties of Bonded–Bolted Hybrid Single-Lap Joints of C/C Composites at High Temperature". Applied Sciences 10, n. 3 (5 febbraio 2020): 1054. http://dx.doi.org/10.3390/app10031054.
Testo completoAbstract (sommario):
Based on previous research, in this paper, the compressive shear failure behavior and mechanical properties of bonded–bolted hybrid single-lap joints of C/C composites at high temperature were studied. The compression shear test was performed on the joints at 800 °C to obtain the load–displacement curve and failure morphology. The failure modes of joints were observed by digital microscopy and scanning electron microscopy. A numerical analysis model was implemented in finite element code Abaqus/Explicit embedded with the user material subroutine (VUMAT). The numerical results were compared with the test results to verify the correctness of the model. The interrelationship of the compression shear loading mechanism and the variations in stress distribution between bonded joints and bonded–bolted hybrid joints at high temperature were explored. The progressive damage of hybrid joints and the variations in the ratio of the bolt load to the total load with displacement were obtained.
11
Yu, Zeliang, Pu Xue e Yue Chen. "Composite Single-Bolted Joint Simulation for Dynamic Strength Prediction". Proceedings 2, n. 8 (2 luglio 2018): 512. http://dx.doi.org/10.3390/icem18-05424.
Testo completoAbstract (sommario):
Composite material has been widely used in various fields for its high specific strength and high specific stiffness, so the connectors applicable to composite structures capture many researchers’ attention. With the advantages of higher carrying capacity and repetitive assembling and disassembling, bolted joint becomes one of the most popular connectors in engineering practice. Cutting off the fiber and causing stress concentration are more serious to composite than metal, so it is necessary to predict the strength of the composite joints. Most investigations focus on the response under quasi-static loading, while dynamic effects should be in consideration in increasing impact conditions. The dynamic mechanical properties of composite joint may have a significant impact on the structural deformation and damage modes. For this purpose, this paper conducts dynamic composite single-bolted joint simulations in ABAQUS/Explicit, which used for predicting dynamic strength of the composite joint. T800/X850 laminates were tested to investigate their dynamic properties in our lab. Then the three-dimension progression damage model was established, while the dynamic constitutive model, damage initial criteria and damage evolution law of composite materials were coded in VUMAT of the finite element software ABAQUS/Explicit. The model was validated by quasi-static experiments of composite joint. The simulation results indicate that the yield strength and ultimate strength of the single-bolted composite joint are obviously increasing when consider the strain rate effect and dynamic loading. And the load-displacement curves show significant difference in damage stage. The main damages are sub-layer buckling and fiber breakage caused by extrusion.
12
Zhuang, Weimin, Jian Sun e Dongxuan Xie. "Modified Deshpande–Fleck Model considering a Variable Plasticity Poisson’s Ratio and a Variable Ellipticity". Advances in Materials Science and Engineering 2022 (16 marzo 2022): 1–14. http://dx.doi.org/10.1155/2022/9235106.
Testo completoAbstract (sommario):
It is controversial whether the plastic Poisson’s ratio and ellipticity are invariable in the Deshpande–Fleck model, which describes the constitutive behavior of foam materials. In this paper, the Deshpande–Fleck model is modified by a variable plasticity Poisson’s ratio and a variable ellipticity based on a nonassociated flow rule. The plasticity Poisson’s ratio is measured by in situ digital image correlation (DIC) technology during the uniaxial compression experiment of aluminum foam. The ellipticity is then determined through the experimental data of uniaxial compression and hydrostatic compression. Both the plastic Poisson’s ratio and the ellipticity vary with the strain. The Hanssen model fitted with uniaxial compression experimental data is used to provide the hardening law for the modified Deshpande–Fleck model. The modified Deshpande–Fleck model is realized by the subroutine VUMAT in ABAQUS/Explicit. There is good agreement between the experimental results and the prediction results of the modified Deshpande–Fleck model under multiaxial compression conditions. Furthermore, the influence mechanism of the plastic Poisson’s ratio and ellipticity on the modified Deshpande–Fleck model are investigated. The results prove that it is necessary to consider both the variable plastic Poisson’s ratio and the variable ellipticity in order to improve the prediction accuracy of the modified Deshpande–Fleck model.
13
Li, Xiang, e Ruiying Luo. "Experimental and Numerical Analysis of Progressive Damage of SiCf/SiC Composite under Three-Point Bending". Crystals 12, n. 5 (18 maggio 2022): 720. http://dx.doi.org/10.3390/cryst12050720.
Testo completoAbstract (sommario):
Satin SiCf/SiC composite has a wide range of applications; it is necessary to study its mechanical properties. The progressive failure of five-harness five-layer satin weave SiCf/SiC plate composites was explored experimentally and numerically in this research. The bending properties were derived and elucidated at ambient temperature through a three-point bending experiment. The generation and progression of damage was observed by CCD camera. For quantitative analysis of the strain field evolution, DIC (digital image correlation) was adopted, while the microscopic analyses were performed for the description of the derived failure markings. With the aid of ABAQUS/Explicit, the experiment was subjected to 3D finite element modeling for the reproduction of the material behavioral, where the VUMAT subroutine was used to implement a 3D-altered criterion of the Hashin damage initiation and the progression law of its complementary damage. Intra-deformation interface failure was simulated with a composite interlayer cohesive zone element. The experimentally derived DIC-based strain fields were well-consistent with the numerical outcomes. Deeper investigation was made into the superiority of the 3D modeling, which is ascribed to the predictability for distribution of complex field variables like the free-edge effect and progressive failure accumulation within the critical sample section. The damage mechanism of the satin weave composite was explored in depth and it provides useful guidance for the practical application of the composite.
14
Cheng, Hang, Zhiqiang Zhang, Mingwen Ren e Hongjie Jia. "Experimental and Numerical Simulation Studies on V-Shaped Bending of Aluminum/CFRP Laminates". Materials 16, n. 14 (11 luglio 2023): 4939. http://dx.doi.org/10.3390/ma16144939.
Testo completoAbstract (sommario):
With the increasing requirements of automotive lightweighting, metal/CFRP laminates are increasingly used. In this paper, Al/CFRP laminates were prepared using an integrated hot press curing method, and the optimum curing conditions were determined using the single-lap shear test at 130 °C for 45 min. The effects of fiber lay-up, forming speed, and metal layer thickness on bending springback were investigated using the V-shaped bending test and Abaqus finite element analysis method. The results show that fiber lay-up has an important influence on springback. Among the five different fiber lay-ups (0° unidirectional, 90° unidirectional, 0° orthotropic, 90° orthotropic, and 45° orthotropic), the 45° orthotropic lay-up had the lowest springback rate of 1.11%. Increasing the thickness of the sheet metal can significantly reduce the resilience rate. As the sheet thickness increased from 2 mm to 3 mm, the springback of the 90° unidirectional lay-up decreased by 43%. Springback was not sensitive to forming speed, and the difference in springback was within 1% at different forming speeds. The damage behavior of the forming process was analyzed using the three-dimensional Hashin damage law with the Vumat subroutine and microscopic analysis. Fiber and resin damage under 45° orthotropic lay-up conditions was relatively small compared to fiber damage under 0° unidirectional lay-up and resin damage under 90° unidirectional lay-up.
15
Chatti, Sami, e Narjess Chtioui. "Sheet metal forming simulation using finite elastoplasticity with mixed isotropic/kinematic hardening". European Journal of Computational Mechanics, 7 agosto 2011, 427–53. http://dx.doi.org/10.13052/ejcm.20.427-453.
Testo completoAbstract (sommario):
A numerical formulation is presented for anisotropic elastoplasticity behavior in finite strain with non-linear isotropic/kinematic hardening model. Non-linear kinematic hardening is modeled by the Lemaitre-Chaboche law with the aim of considering cyclic deformation phenomena. User-defined material subroutines are developed based on Hill’s quadratic yield function for both ABAQUS-Explicit (VUMAT) and ABAQUS-Standard (UMAT). For validation purpose, the tension-compression and cyclic shear tests are simulated. Several sheet forming processes including contact, anisotropic plasticity, elastic modulus variation with plastic strain and springback effects are simulated. Numerical results are compared with experimental data.
16
Duc-Toan, Nguyen, Banh Tien-Long, Jung Dong-Won, Yang Seung-Han e Kim Young-Suk. "A Modified Johnson–Cook Model to Predict Stress-strain Curves of Boron Steel Sheets at Elevated and Cooling Temperatures". High Temperature Materials and Processes 31, n. 1 (1 gennaio 2012). http://dx.doi.org/10.1515/htmp.2011.127.
Testo completoAbstract (sommario):
AbstractIn order to predict correctly stress-strain curve for tensile tests at elevated and cooling temperatures, a modification of a Johnson–Cook (J-C) model and a new method to determine (J-C) material parameters are proposed. A MATLAB tool is used to determine material parameters by fitting a curve to follow Ludwick and Voce's hardening law at various elevated temperatures. Those hardening law parameters are then utilized to determine modified (J-C) model material parameters. The modified (J-C) model shows the better prediction compared to the conventional one. An FEM tensile test simulation based on the isotropic hardening model for metal sheet at elevated temperatures was carried out via a user-material subroutine, using an explicit finite element code. The simulation results at elevated temperatures were firstly presented and then compared with the measurements. The temperature decrease of all elements due to the air cooling process was then calculated when considering the modified (J-C) model and coded to VUMAT subroutine for tensile test simulation. The modified (J-C) model showed the good comparability between the simulation results and the corresponding experiments.
17
Ahmad, Bilal, e Xiangfan Fang. "Strain rate-dependent crash simulation of woven glass fabric thermoplastic composites". Journal of Reinforced Plastics and Composites, 17 febbraio 2022, 073168442110642. http://dx.doi.org/10.1177/07316844211064235.
Testo completoAbstract (sommario):
Woven fabric thermoplastic composites possess high specific strength and stiffness along with thermoformability. To utilize the full potential of these materials to achieve better crash-safe designs in automotive structural parts, their crash behavior must be predicted accurately. For reliable crash simulations, strain rate-dependent material data and equally capable material modeling are required. In this study, quasi-static and high-speed tests are carried out to measure tensile and in-plane shear properties. A strain rate-dependent continuum damage mechanics model is formulated to describe the deformation and damage behavior of woven glass fabric composites. Tensile and in-plane shear tests on a lab scale are used to calibrate the material parameters of the model. The model was implemented as a user-defined material subroutine (VUMAT) for Abaqus. Experimental results from coupon tests were used to verify the results of a single-element simulation. Finally, a structural level dynamic crash test of a u-profile on a drop tower was used to validate the predictions of the user material model.