Journal articles: 'Elasto-plastic validation'

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Deb, Debasis, and Kamal C. Das. "Bolt-Grout Interactions in Elastoplastic Rock Mass Using Coupled FEM-FDM Techniques." Advances in Civil Engineering 2010 (2010): 1–13. http://dx.doi.org/10.1155/2010/149810.

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Numerical procedure based on finite element method (FEM) and finite difference method (FDM) for the analysis of bolt-grout interactions are introduced in this paper. The finite element procedure incorporates elasto-plastic concepts with Hoek and Brown yield criterion and has been applied for rock mass. Bolt-grout interactions are evaluated based on finite difference method and are embedded in the elasto-plastic procedures of FEM. The experimental validation of the proposed FEM-FDM procedures and numerical examples of a bolted tunnel are provided to demonstrate the efficacy of the proposed method for practical applications.

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Veselý, Jan. "NUMERICAL MODELLING OF THE SOIL BEHAVIOUR BY USING NEWLY DEVELOPED ADVANCED MATERIAL MODEL." Acta Polytechnica 57, no. 1 (2017): 58–70. http://dx.doi.org/10.14311/ap.2017.57.0058.

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This paper describes a theoretical background, implementation and validation of the newly developed Jardine plastic hardening-softening model (JPHS model), which can be used for numerical modelling of the soils behaviour. Although the JPHS model is based on the elasto-plastic theory, like the Mohr-Coulomb model that is widely used in geotechnics, it contains some improvements, which removes the main disadvantages of the MC model. The presented model is coupled with an isotopically hardening and softening law, non-linear elastic stress-strain law, non-associated elasto-plastic material description and a cap yield surface. The validation of the model is done by comparing the numerical results with real measured data from the laboratory tests and by testing of the model on the real project of the tunnel excavation. The 3D numerical analysis is performed and the comparison between the JPHS, Mohr-Coulomb, Modified Cam-Clay, Hardening small strain model and monitoring in-situ data is done.

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Piven, V. V., and G. E. Bityukov. "VALIDATION OF THE MATHEMATICAL MODEL OF FRAME CONSTRUCTION STRESS-STRAIN STATE." Oil and Gas Studies, no. 3 (June 30, 2015): 107–11. http://dx.doi.org/10.31660/0445-0108-2015-3-107-111.

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The problem of optimization of the stress-strain state of spatial beam structures with incorporation on elasto-visco-plastic base was reviewed. The rheological models of bases were analyzed. A block diagram of the mathemati-cal model of the construction optimization was developed. The objective function for optimization was defined.

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Karg, C., S. François, W. Haegeman, and G. Degrande. "Elasto-plastic long-term behavior of granular soils: Modelling and experimental validation." Soil Dynamics and Earthquake Engineering 30, no. 8 (2010): 635–46. http://dx.doi.org/10.1016/j.soildyn.2010.02.006.

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Kim, Hee-Seong, Seung-Gyo Jang, Nam-Ho Kim, and Joo-Ho Choi. "Statistical calibration and validation of elasto-plastic insertion analysis in pyrotechnically actuated devices." Structural and Multidisciplinary Optimization 54, no. 6 (2016): 1573–85. http://dx.doi.org/10.1007/s00158-016-1545-8.

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Paparizos, L. G., and W. D. Iwan. "Some Observations on the Random Response of an Elasto-Plastic System." Journal of Applied Mechanics 55, no. 4 (1988): 911–17. http://dx.doi.org/10.1115/1.3173741.

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The nature of the response of strongly yielding systems subjected to random excitation, is examined. Special attention is given to the drift response, defined as the sum of yield increments associated with inelastic response. Based on the properties of discrete Markov process models of the yield increment process, it is suggested that for many cases of practical interest, the drift can be considered as a Brownian motion. The approximate Gaussian distribution and the linearly divergent mean square value of the process, as well as an expression for the probability distribution of the peak drift response, are obtained. The validation of these properties is accomplished by means of a Monte Carlo simulation study.

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MA, YONG, ZHAO YANG, SHENGWANG YU, et al. "ELASTO-PLASTIC PROPERTIES OF Mo-MODIFIED Ti DEDUCED FROM INDENTATION TESTS AND FINITE ELEMENT ANALYSIS." Surface Review and Letters 26, no. 07 (2019): 1850225. http://dx.doi.org/10.1142/s0218625x18502256.

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The aim of this paper is to establish an approach to quantitatively determine the elasto-plastic parameters of the Mo-modified Ti obtained by the plasma surface alloying technique. A micro-indentation test is conducted on the surface under 10[Formula: see text]N. Considering size effects, nanoindentation tests are conducted on the cross-section with two loads of 6 and 8[Formula: see text]mN. Assuming nanoindentation testing sublayers are homogeneous, finite element reverse analysis is adopted to determine their plastic parameters. According to the gradient distributions of the elasto-plastic parameters with depth in the Mo-modified Ti, two types of mathematical expressions are proposed. Compared with the polynomial expression, the linear simplified expression does not need the graded material to be sectioned and has practical utility in the surface treatment industry. The validation of the linear simplified expression is verified by the micro-indentation test and corresponding finite element forward analysis. This approach can assist in improving the surface treatment process of the Mo-modified Ti and further enhancing its load capacity and wear resistance.

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Galavi, Vahid. "DeltaSand: A state dependent double hardening elasto-plastic model for sand: Formulation and validation." Computers and Geotechnics 129 (January 2021): 103844. http://dx.doi.org/10.1016/j.compgeo.2020.103844.

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Bartkowski, Piotr, and Robert Zalewski. "Empirical determination of the mechanical properties of Vacuum Packed Particles." MATEC Web of Conferences 254 (2019): 05008. http://dx.doi.org/10.1051/matecconf/201925405008.

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In this work the experimental test of Vacuum Packed Particles (VPP) under 3-point bending are presented. VPP it is the structure compose of grains inside the plastomer coating. When the pressure inside is equal or higher than zero structure behave like a liquid, otherwise like a elasto-plastic solid. Three types of grain material and different values of underpressure were tested. Results presented in this paper will be used in the further work for the numerical model validation procedure.

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HASHIMOTO, Ryota, Tomofumi KOYAMA, Mamoru KIKUMOTO, and Mamoru MIMURA. "Development of an enhanced elasto-plastic NMM-DDA with node-based element and its validation." Japanese Geotechnical Journal 11, no. 2 (2016): 163–77. http://dx.doi.org/10.3208/jgs.11.163.

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Gui, Zhong-xiang, Xiao Hu, and Zi-jian Wang. "An elasto-visco-plastic constitutive model of polypropylene incorporating craze damage behavior and its validation." Journal of Central South University 24, no. 6 (2017): 1263–68. http://dx.doi.org/10.1007/s11771-017-3530-9.

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Faruq, Namiq Zuhair, and Luca Susmel. "The elasto-plastic Point Method to estimate fatigue lifetime of notched metallic materials under variable amplitude multiaxial fatigue loading." MATEC Web of Conferences 300 (2019): 13004. http://dx.doi.org/10.1051/matecconf/201930013004.

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The present paper deals with the formulation and implementation of a novel fatigue lifetime estimation technique suitable for designing notched components against multiaxial fatigue. This fatigue assessment procedure was devised by combining the Modified Manson-Coffin Curve Method and the Shear Strain-Maximum Variance Method with the elasto-plastic Point Method. The accuracy of the approach being proposed was checked against a large number of experimental results that were generated by testing notched cylindrical samples of medium-carbon steel En8. These tests were run under proportional/non-proportional constant/variable amplitude biaxial loading, with the effect of non-zero mean stresses and different frequencies between the axial and torsional stress/strain components being also investigated. The results from this validation exercise demonstrate that the novel multiaxial fatigue assessment methodology being proposed is highly accurate, with its systematic usage resulting in predictions falling within an error factor of 2. This remarkable level of accuracy is very promising especially in light of the fact that this approach can be applied by directly post-processing the results from elasto-plastic Finite Element (FE) models solved using commercial codes.

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Guerin, Caroline, Chantal Cappelaere, and Marc Ton-That. "CAST3M modelling of dynamic experiments on PWR high burn-up fuel rods equivalent fuel rod modelling approach validation." Mechanics & Industry 20, no. 8 (2019): 808. http://dx.doi.org/10.1051/meca/2020054.

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Spent fuel transport and handling operating rules exclude any accidental risk. However, in the framework of the PRECCI R&D project, the impact on a spent fuel rod is taken into account. This study was carried out in CEA laboratories with the funding and the technical support of EDF. Since fuel rods are slender structures, it is of particular interest to model them with one dimensional finite elements. While the zirconium alloy elasto-plastic law can be directly used for the plugs and plenum regions, an equivalent stress-strain law is necessary for the fuel column level, especially in the case of high burnups since the contact between the pellets and the clad reinforce the contribution of the fuel to the rod mechanical behavior. The equivalent law as well as the correlation between the clad and the equivalent plastic strain were established from CAST3M finite element modelling of four point bending of fuel rods segments. This model, meshed with three dimensional elements, takes into account elasto-plastic behavior for the clad and cracking of the UO2 fuel pellets. Bending experiments on spent fuel rods performed at LCMI laboratory allowed to validate this modelling as reported in a previous article. The axial dynamic load impact tests performed by Hirose et al. on PWR fuel rods specimens were modelled with CAST3M with one dimensional elements using the determined equivalent law. The maximum loads calculated with the equivalent law are in excellent agreement with the experimental results. The deformed shapes as well as the failure modes are also in good agreement. The maximum calculated strains reach the fracture strain of the rods at the location where the failures are observed experimentally. This study reinforces the confidence in the equivalent law. It moreover indicates that zircaloy behavior for dynamic loadings can be modelled with the laws established at lower strain rates, as suggested by the moderate variation of the mechanical properties as a function of strain rates determined by dynamic tensile tests from literature.

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Okaya, Naotoshi, Tomohiro ITO, and Katsuhisa Fujita. "417 Vibration Reduction Effects of Elasto-Plastic Glannular Material Impact Dampers : 3-dimensional Effects and Experimental Validation." Proceedings of Conference of Kansai Branch 2007.82 (2007): _4–23_. http://dx.doi.org/10.1299/jsmekansai.2007.82._4-23_.

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Hu, Fangxin, Gang Shi, and Yongjiu Shi. "Constitutive model for full-range elasto-plastic behavior of structural steels with yield plateau: Calibration and validation." Engineering Structures 118 (July 2016): 210–27. http://dx.doi.org/10.1016/j.engstruct.2016.03.060.

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Uzan, J., M. Perl, and A. Sides. "Numerical simulation of fatigue creep crack growth in a visco-elasto-plastic material—II. experimental validation and application." Engineering Fracture Mechanics 23, no. 2 (1986): 333–44. http://dx.doi.org/10.1016/0013-7944(86)90079-2.

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Unger, Andreas, Walter Sextro, Simon Althoff, et al. "Experimental and Numerical Simulation Study of Pre-deformed Heavy Copper Wire Wedge Bonds." International Symposium on Microelectronics 2014, no. 1 (2014): 000289–94. http://dx.doi.org/10.4071/isom-tp44.

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To implement a self-optimization technique for ultrasonic wire bonding machines, a model of the pre-deformation phase is essential. The local material characteristics change abruptly because of the cold work during deformation. Investigations confirm a significant influence on the material properties of the contact members during touchdown. In a first step this paper validates the importance of modeling the pre-deformation experimentally. In a second step, the paper presents a numerical study of the elasto-plastic deformation based on the finite element method. This model includes measured overshoots in the touchdown forces in order to achieve accurate model responses. A validation of the model with the resulting nominal contact area, surface pressure and penetration depth reveals the high model quality.

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Jousset, P., and M. Rachik. "Implementation, identification and validation of an elasto-plastic-damage model for the finite element simulation of structural bonded joints." International Journal of Adhesion and Adhesives 50 (April 2014): 107–18. http://dx.doi.org/10.1016/j.ijadhadh.2014.01.020.

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19

Michel, B., and J. C. Boyer. "Elasto-visco-plastic finite-element analysis of a cold upsetting test and stress-state validation by residual-stress measurements." Journal of Materials Processing Technology 54, no. 1-4 (1995): 120–28. http://dx.doi.org/10.1016/0924-0136(95)01930-8.

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20

Patil, Sandip, Digvijay Sheed, and Rajkumar Singh. "FE Modelling of Residual Stresses and Validation Using Chip-Mechanism and Microstructural Analysis of Ultrasonic Vibration Assisted Turning of Ti Alloy Ti-6Al-4V." Applied Mechanics and Materials 597 (July 2014): 257–61. http://dx.doi.org/10.4028/www.scientific.net/amm.597.257.

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Ultrasonic assisted turning (UAT) is a novel manufacturing technology, where high frequency vibrations are imposed on the movement of a cutting tool. A 2D FE transient simulation is developed in DEFORM, where ultrasonic vibrations of frequency 20 kHz and amplitude of 20 μm are provided to the cutting tool in the direction of cutting velocity. The prediction of residual stress distribution is carried out using elasto-plastic finite element simulations. Experimental analysis is carried out in measuring the strain at the cutting tool during CT and UAT along with the chip mechanism and chip microstructure study to validate the residual stress distribution. The ultrasonic vibrations yield a considerable improvement in compressive residual stresses which ultimately benefits in improving fatigue life of titanium alloys.

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Kant, Chandra, and G. A. Harmain. "A Model Based Study of Fatigue Life Prediction for Multifarious Loadings." Key Engineering Materials 882 (April 2021): 296–327. http://dx.doi.org/10.4028/www.scientific.net/kem.882.296.

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Loading history makes fatigue crack propagation modelling complex. This article focus on life prediction models which take into consideration the variability of fluctuating loads. In particular it emphases on the comparative studies of prediction models involving the significance of one model’s over another. The paper studies models based on multifarious loadings (constant amplitude load, variable amplitude load, overload/underload etc.). The major parameters of load interaction modelling are plasticity, crack closure, effective stress intensity, effective stress ratio and damage accumulation. For large deformation, elasto-plastic fracture mechanics based models are also included. The complexity of models, their features and focusing on their limitation and strengths are stated with various conditions and also validation of models with experimental data are reported. The paper speculates on the directions the study of crack propagation will take in future.

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Lyapichev, Yury P. "Static and dynamic analyses of the heightening of concrete face gravel dam Limon (Peru)." Structural Mechanics of Engineering Constructions and Buildings 15, no. 2 (2019): 158–68. http://dx.doi.org/10.22363/1815-5235-2019-15-2-158-168.

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Aims of research. Expert validation of all proposed design solutions, development of necessary design solutions for the heightening of the Limon dam according to the ICOLD recommendations. Methods. The detailed static and seismic (dynamic) analyses of stressstrain state and seepage of concrete face rockfill dam Limon (Peru) were performed using the advanced software FLAC-3D (USA) and PLAXIS 2D (Holland), respectively. The elasto-plastic model with Mohr - Coulomb criterion with variable shear angles of gravel and pebble zones of dam materials and its foundation soils was used in the static and seismic (dynamic) analyses of the dam. The dynamic nonlinear analyses of stress-strain state of two variants of Limon dam with full reservoir under Maximum Credible Earthquake (MCE) action of the Mar-Chile Earthquake accelerogram. Results. On the base of these analyses the recommendations were developed for the project of the dam heightening from 43 up to 82 m before the initial filling of the reservoir. Expert validation of all proposed design solutions, necessary design solutions for the heightening of the Limon dam were developed according to the ICOLD recommendations.

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Chukkan, Jazeel Rahman, M. Vasudevan, S. Muthukumaran, et al. "Numerical Simulation of Pulsed Nd-YAG Laser Butt Welding of AISI 304L Stainless Steel Sheet and Experimental Validation." Applied Mechanics and Materials 592-594 (July 2014): 565–70. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.565.

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The objective of this work is to carry out thermo-elasto-plastic analysis of pulsed Nd-YAG laser-beam butt welding of 304L Stainless Steel sheets using Finite Element Modelling. Thermo-mechanical analysis was done by using commercial Finite Element software SYSWELD. Thermal analysis provided thermal cycles and weld bead geometry. Then using thermo-mechanical analysis, residual stresses and distortion values were estimated. In order to validate the model predictions, a single pass autogenous welding with pulsed laser beam was performed on 304L stainless steel sheets. Thermocouples were used to record temperatures at different places close to the fusion line. Vertical displacements after welding were measured using Vertical height gauge equipment. The longitudinal residual stress after welding was measured using an ultrasonic technique. Metallography was employed to view the cross sections of the weld bead. The Finite Element Analysis results were then compared with experimental results. Thermal cycles, distortion and residual stresses obtained in FEA and experiments were found to be in good agreement.

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Schulenberg, L., T. Seelig, F. Andrieux, and D.-Z. Sun. "An anisotropic elasto-plastic material model for injection-molded long fiber-reinforced thermoplastics accounting for local fiber orientation distributions." Journal of Composite Materials 51, no. 14 (2016): 2061–78. http://dx.doi.org/10.1177/0021998316668983.

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This paper presents an anisotropic elasto-plastic material model for injection-molded long fiber-reinforced thermoplastics. It considers local heterogeneities which are attributed to process-induced variations of fiber orientation distributions and fiber volume fractions. These inhomogeneities have an effect on the mechanical properties and need to be considered in structural computations. In the material model, this is realized through a two-step homogenization procedure. First, an anisotropic stiffness tensor is approximated using mean field homogenization. Second, the plastic behavior is described using Hill’s transversely isotropic yield criterion averaged over the three principal directions of the fiber orientation. The advantage in combining these two approaches is a micro-mechanically based, yet fast numerical calculation of the composite material behavior within an explicit finite element code. The anisotropic material model is calibrated by simulating tensile tests on specimens taken in different directions from an injection-molded plate of fiber reinforced thermoplastic. The spatial variation of fiber orientation distribution and fiber volume fraction throughout the plate is determined from numerical mold filling simulations and is compared with computer tomography scans at different positions. A validation of the model is performed through simulating position-dependent tensile tests on smooth and notched specimens as well as a punch test which is well reproduced.

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Kamenar, Ervin, and Saša Zelenika. "Issues in validation of pre-sliding friction models for ultra-high precision positioning." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 3 (2018): 997–1006. http://dx.doi.org/10.1177/0954406218758797.

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Friction is one of the main disturbances in nanometric positioning. Recently, it was shown that ultra-high precision positioning typically happens in the pre-sliding motion regime where friction is characterized by an elasto-plastic nonlinear hysteretic behavior with a marked stochastic variability. With the aim of providing the tools for the development of robust control typologies for ultra-high precision mechatronics devices, different pre-sliding friction models are thus considered in this work. The most relevant ones are hence experimentally validated, as well as compared in terms of the complexity of identifying their characteristic parameters and of simulating the factual dynamic response. It is hence shown that the generalized Maxwell-slip model can account for all the important pre-sliding frictional effects in nanometric positioning applications. A thorough sensitivity analysis of the parameters of the generalized Maxwell-slip model model is therefore performed allowing to establish that three Maxwell-slip blocks are the minimum needed to approximate the behavior of the real precision positioning systems, six blocks allow representing excellently the real behavior, while the slower dynamics, which induces a difficult real-time implementation, with a very limited gain in terms of model accuracy, does not justify the usage of a larger number of elements.

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Yang, Cheng Zhong, and Wen Jie Wan. "Finite Element Analysis on High Embankment of Widened Road." Applied Mechanics and Materials 63-64 (June 2011): 770–74. http://dx.doi.org/10.4028/www.scientific.net/amm.63-64.770.

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By means of finite element method software simulation analysis, using strength reduction finite element method analyse factor of safety of embankments. Nowadays most finite element program is analyzed in the perfect elasto-plastic with the Mohr-Coulomb not equiangular hexagon circumcircle Drucker-Prager yield criterion, it have margin of error with not equiangular hexagon in π-plane, so we use Mohr-Coulomb equivalent area circle D-P yield criterion instead of it. Calculate conversion coefficient of two safety factor under different yield criterion. Using safety factor through finite element software by strength reduction multiply by conversion coefficient, get new safety factor. Through the example of high embankment of old road widened in Shanghai-Chengdu expressway Hejiaping cable section K2+ 710~890, validation of this method calculated the accuracy of the safety factor, the results show that the new factor of safety closer to the true value.

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Kotha, Shravan, Deniz Ozturk, and Somnath Ghosh. "Parametrically homogenized constitutive models (PHCMs) from micromechanical crystal plasticity FE simulations: Part II: Thermo-elasto-plastic model with experimental validation for titanium alloys." International Journal of Plasticity 120 (September 2019): 320–39. http://dx.doi.org/10.1016/j.ijplas.2019.05.007.

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Narayanareddy, V. V., M. Vasudevan, S. Muthukumaran, K. C. Ganesh, N. Chandrasekhar, and P. Vasantaraja. "Finite Element Modeling of TIG Welding of Aisi 304l Stainless Steel and Experimental Validation." Applied Mechanics and Materials 592-594 (July 2014): 368–73. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.368.

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In this research work, thermo-elasto-plastic analysis using finite element modeling (FEM) was carried out to study the thermo mechanical behavior of AISI 304L stainless steel plate of 3 mm thick during the autogenous tungsten inert gas welding. Sysweld software has been employed for simulating the temperature distribution, residual stresses and distortion. Physical and mechanical properties of 304 L stainless steel required for simulation were obtained from the literature. Bead-on-plate experiment was carried out at 140 A and 120 mm/min for obtaining weld bead dimensions which are required for heat source fitting in the simulation. Heat source parameters in the simulation were frozen when the bead profile obtained in the simulation matched with the actual bead profile. Then thermal cycles were simulated with the frozen heat source parameters. The thermal cycles and the peak temperatures predicted by the model were compared with that of the experimentally measured values. There was good agreement between the predicted and measured values. The experimentally validated thermal model was further used for simulating residual stresses and distortion. The calculated residual stress profile was validated using experimentally measured residual stress profiles using an Ultrasonic technique. There was good agreement between the predicted and measured residual stress profiles. The simulated distortion values were compared with measured distortion values using height gauge. There was good agreement between the simulated and measured distortion values. The Finite Element model developed for simulating the TIG welding of 304 L stainless steel predicted the thermal cycles, residual stresses and distortion with minimum error.

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Casavola, C., V. Moramarco, and C. Pappalettere. "Experimental and Numerical Characterization of the Impact Response of Polyethylene Sandwich Panel: A Preliminary Study." Applied Mechanics and Materials 70 (August 2011): 195–200. http://dx.doi.org/10.4028/www.scientific.net/amm.70.195.

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The present work present a preliminary study to evaluate the impact response of a new sandwich panel, made up of two polyethylene skins separated by lightweight polyethylene foam. An impact test campaign was conducted on 15 square specimens (side 100 mm, total height 44 mm, average skins height 2.75 mm) with not macroscopic defects, obtained by three homogenous panels. The absorbed energy, the force and the crosshead velocity were recorded during the test. Three level of impact energy were considered. Experimental tests have allowed to obtain the impact energy/acceleration and the peak stress/impact energy diagrams for this material. Moreover, the specimen profile of the section that passes through the impact area was obtained before the test, just after the impact and one hour later for each specimen. Subsequently the experiment was reproduced by means of solid explicit finite element (FE) model in Abaqus. In order to simulate as real as possible the panel behaviour, the skins were modelled as elasto-plastic material while the core was simulated as elastomeric hyperfoam material. The material constants were based on previous experimental data conducted on the same material. After the FEM model validation, the stress-strain resulting maps were plotted.

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Haufe, André, Andrea Erhart, and Alexander Butz. "A Constitutive Model for the Simulation of the Deformation Behavior of TWIP Steels." Key Engineering Materials 639 (March 2015): 411–18. http://dx.doi.org/10.4028/www.scientific.net/kem.639.411.

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Due to their high strength (tensile strength > 1GPa) in combination with an extreme ductility (failure strain 30-50%) TWinning Induced Plasticity–steels (TWIP-steels) can be considered as promising materials for the production of lightweight automotive components. The industrial application of TWIP-steels requires a fundamental experimental validation of the mechanical behavior as basis for an user-friendly but at the same time accurate constitutive framework and its implementation into commercial Finite Element codes. Related investigations and implementations in order to allow for the simulation of TWIP-steel forming processes are currently conducted within the research project “TWIP4EU”, executed as a cooperation of Fraunhofer - Institut für Werkstoffmechanik IWM in Freiburg (Germany), Salzgitter Mannesmann Forschung GmbH (Germany), Swerea KIMAB (Sweden), Faurecia Autositze GmbH (Germany / France), DYNAmore GmbH (Germany) and ESI GmbH Engineering System (Germany / France).The monotonic one-dimensional hardening behavior of TWIP-steels as a function of the twin volume fraction and dislocation density has been described by Bouaziz et al. (2008), Bouaziz et al. (2011). This model has been proven to be adequate for the description of the flow behavior of TWIP-steels and serves as basis for the constitutive model, presented here. This Bouaziz-model has been extended to a three-dimensional elasto-plastic formulation, including the influence of different loading conditions, anisotropy and kinematic hardening. The present paper deals with the implementation for solids and shells in the commercial Finite Element Code LS-DYNA®and appropriate validation simulations will be presented.

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Bedon, Chiara, and Claudio Amadio. "Passive Control Systems for the Blast Enhancement of Glazing Curtain Walls Under Explosive Loads." Open Civil Engineering Journal 11, no. 1 (2017): 396–419. http://dx.doi.org/10.2174/1874149501711010396.

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Glass curtain walls are used in modern buildings as envelopes for wide surfaces due to a multitude of aspects. In glass curtain walls, tensile brittle panels are connected - through mechanical or adhesive joints - with steel frameworks or aluminum bracing systems, and due to the interaction of several structural components, the behaviour of the so assembled system is complex to predict, especially under exceptional loading conditions such as explosive events. In the paper, glazing curtain walls are investigated by means of Finite-Element (FE) numerical simulations, under the effect of air blast pressures of variable intensity. Their typical dynamic behaviour and criticalities under high-strain impact loads are first analyzed. By means of extended nonlinear dynamic FE parametric studies, innovative devices are applied to traditional curtain walls, at their support points, in order to improve their expected dynamic response. Two possible solutions, namely consisting of viscoelastic (VE) or elasto-plastic (PL) dampers, are proposed as passive control systems for the mitigation of maximum effects in the façade components deriving from the incoming blast pressures. As shown, although characterized by specific intrinsic mechanical behaviours, either VE or PL dampers can offer beneficial structural effects. In the first case, major advantages for the façade components derive from the additional flexibility and damping capacities of VE devices. In the latter case, PL dampers introduce additional plastic energy dissipation in the traditional curtain wall assembly, hence allowing preventing severe damage in the glazing components. It is thus expected that the current outcomes could represent a valid background for further experimental validation as well as detailed assessment and optimization of the proposed design concept.

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Laurent, Cédric P., Béatrice Böhme, Jolanthe Verwaerde, Luc Papeleux, Jean-Philippe Ponthot, and Marc Balligand. "Effect of orthopedic implants on canine long bone compression stiffness: a combined experimental and computational approach." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 234, no. 3 (2019): 255–64. http://dx.doi.org/10.1177/0954411919882603.

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Osteosynthesis for canine long bones is a complex process requiring knowledge of biology, surgical techniques and (bio)mechanical principles. Subject-specific finite element analysis constitutes a promising tool to evaluate the effect of surgical intervention on the global properties of a bone–implant construct, but suffers from a lack of validation. In this study, the biomechanical behavior of 10 canine humeri was compared before and after creation of a 10 mm bone defect stabilized with an eight-hole locking compression plate (Synthes®) and two locking screws on each fragment. The response under compression of both intact and plated samples was measured experimentally and reproduced with a finite element model. The experimental stiffness ratio between plated and intact bone was equal to 0.39 ± 0.06. A subject-specific finite element analysis including density-dependent elasto-plastic material properties for canine bone and automatic generation of orthopedic implants was then conducted to recover these experimental results. The stiffness of intact and plated samples could be predicted, with no significant differences with experimental data. The simulated stiffness ratio between plated and intact canine bone was equal to 0.43 ± 0.03. This study constitutes a first step toward the building of a virtual database of pre-computed cases, aiming at helping the veterinary surgeons to make decisions regarding the most suited orthopedic solution for a given dog and a given fracture.

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Velay, Vincent, Gérard Bernhart, A. Martinier, and Jean Yves Moraux. "High Temperature Fatigue of SPF Die Ni-Cr-Fe Heat Resistant Nickel-Chromium Cast Steels." Key Engineering Materials 433 (March 2010): 69–76. http://dx.doi.org/10.4028/www.scientific.net/kem.433.69.

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Superplastic forming of titanium alloy sheets requests long time operating conditions in the range of 900-950°C. Moreover, in a classical press-furnace process environment, die surface temperature drops during sheet unloading and induces high temperature thermo-mechanical fatigue. In order to withstand such extreme conditions in oxidative atmosphere, cast heat resistant nickel chromium steel grades have been developed. The high chromium content (close to 25%) aims to protect against the oxidizing environment, whereas the nickel content is selected with respect to the expected in service loads. The 50% nickel grades are in general used for heating plates, huge casings and cover-plates; whereas 40% nickel grades are selected for inserts and medium size self-standing dies. Cost considerations (Nickel and machining) are also taken into account by the end users for making their choice. An extensive testing program has been performed, in the range of 20 to 950°C, to understand the high temperature fatigue behaviour of these grades and to identify material behaviour models for simulation purposes. This paper presents the major results of these research works and highlights the impact of the nickel content in terms of stress level and life time. Nevertheless, when looking on behaviour, test results show that a unified elasto-visco-plastic cyclic behaviour model is well suited for thermo-mechanical cyclic modelling whatever the grade is. Isothermal identification strategy and out of phase SPF die representative anisothermal fatigue validation are presented.

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Occhipinti, Giuseppe, Francesco Cannizzaro, Salvatore Caddemi, and Ivo Caliò. "A Discrete Macro Element Method for Modelling Ductile Steel Frames around the Openings of URM Buildings as Low Impact Retrofitting Strategy." Sustainability 13, no. 17 (2021): 9787. http://dx.doi.org/10.3390/su13179787.

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This paper adopts the use of steel frames around existing openings as a low-impact seismic retrofitting strategy for unreinforced masonry structures (URM). Although elastic steel frames have been commonly adopted for strengthening masonry walls in case of the realization of new openings, the use of elasto-plastic frames has been proposed only recently. This study adopts the application of low-resistance ductile steel frames on the openings of existing masonry buildings as a low-impact retrofitting strategy. The adopted low-invasive solution possesses the advantage of increasing the in-plane resistance of the masonry wall, improving the displacement capacity, introducing additional energy dissipation under dynamic loadings, and providing a confinement effect on the adjacent masonry piers. An original aspect of the present paper is related to the adopted numerical method for modelling the presence of the steel frames around the openings. Namely, a Discrete Macro-Element Method (DMEM), which allows an efficient and reliable simulation of the involved collapse mechanisms of the masonry walls interacting with the frames, has been adopted. After the validation of the numerical approach, through a comparison with experimental results already reported in the literature, the low-impact strategy has been applied on a benchmark known as the “via Martoglio building”. The obtained results suggest that this low-impact retrofitting strategy can be successfully proposed for URM buildings and can be efficiently modelled by means of the DMEM.

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Kala, Shirish R., N. Siva Prasad, and G. Phanikumar. "Numerical Studies on Effect of Interpass Time on Distortion and Residual Stresses in Multipass Welding." Advanced Materials Research 601 (December 2012): 31–36. http://dx.doi.org/10.4028/www.scientific.net/amr.601.31.

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Weld distortion and residual stresses are two major issues in the fabrication process. Numerical techniques are being tried out to accurately predict the structural integrity of the welding. Interpass time in the multipass welding is an important parameter which influences the weld distortion and residual stresses. In this study two pass tungsten inert gas (TIG) welding of 6 mm mild steel plates has been analyzed using Finite element analysis (FEA) software Sysweld and parametric study is conducted with different interpass time. The temperature distribution, distortion and residual stresses are calculated using three dimensional finite element model (FEM) considering phase transformations in the material. The transient thermo-metallurgical analysis followed by elasto-plastic analysis is carried out using temperature dependent and phase dependent material properties. The material deposition in the multipass welding is numerically simulated using chewing gum method, where dummy phase and dummy material are assigned for the element activation. The phase proportions are calculated by assigning suitable phase kinetics parameter extracted from continuous cooling transformation (CCT) diagram of a given material. Experiments are conducted for validation after given edge preparation and using same material as filler wire. The FEM analysis is carried out for eight cases with different time interval between passes, starting from 30 s to 240 s in the steps of 30 s. FEM results are verified with experimentally measured values. It is found that the time interval between passes has less influence on the residual stresses but significantly affects the distortion and phase proportion due to the first pass preheating effect on second pass and second pass postheating effect on first pass.

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Kubo, Gai, Tetsuya Matsuda, Hiroma Nagaoka, and Yoshihiko Sato. "Development and Validation of Multiscale Thermo-Elasto-Viscoplastic Analysis Method for Plain-Woven Composites." Key Engineering Materials 794 (February 2019): 78–88. http://dx.doi.org/10.4028/www.scientific.net/kem.794.78.

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In this study, the analysis method for thermomechanical properties of plain-woven composites is developed, and applied to thermoelastoviscoplastic analysis of plain-woven glass fiber-reinforced plastic (GFRP) composites. For this, a time-dependent constitutive equation depending on temperature for matrix materials is incorporated into the micro/meso/macro-scale thermo-elastic homogenization method for plain-woven composites developed by our research group. This method enables us to analyze thermoelastoviscoplastic properties in not only fiber bundles but also fibers and matrix materials in fiber bundles, as well as macroscopic thermal properties. This method is then applied to the thermal expansion analysis of a plain-woven GFRP composite subjected to a macroscopic temperature change from 25°C to 80°C before it is cooled to 25°C. Comparing the analysis results with experimental data, we validate the present method. It is also shown that the present method can evaluate themal residual stress and strain in the composite.

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Yeow, Trevor Z., Gregory A. MacRae, Rajesh P. Dhakal, and Brendon A. Bradley. "Validating the sliding mechanics of office-type furniture using shake-table experiments." Bulletin of the New Zealand Society for Earthquake Engineering 51, no. 1 (2018): 1–11. http://dx.doi.org/10.5459/bnzsee.51.1.1-11.

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Pull-tests and shake-table tests of office-type furniture on carpet and vinyl flooring were performed to obtain friction coefficients, and validate the mechanics of content sliding and current modelling approaches. The static friction coefficient, μs, for furniture with and without wheels was between 0.13-0.30 and 0.36-0.45 on carpet flooring, respectively, and 0.07-0.13 and 0.39-0.45 on vinyl flooring, respectively. The kinetic friction coefficient, μk, was similar to μs for carpet flooring, but was up to 38% lower for vinyl flooring. Shake-table tests using sinusoidal floor excitations showed that: (i) the sliding force hysteresis loop was elasto-plastic on average, and (ii) peak total floor velocity significantly affected the extent of sliding. While it was found that the maximum sliding displacement obtained by numerical integration methods differed by a factor between 0.3 and 3.0 on a case-by-case basis, the average error was just 5%. Preliminary sliding analyses of furniture resting on single-degree-of-freedom structures of varying stiffness using a suite of ground motion records were performed. It was found that (i) the extent of sliding was not necessarily more severe in stiffer buildings despite the greater peak total floor acceleration demands, and (ii) considering only μk in content sliding analyses still produced reasonably accurate predictions.

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Jiang, Bingyun, and Chen Tian. "Integrated Prediction of Mechanical Behavior for the Non-Aligned Fiber Composites With Experimental Validation." Journal of Engineering Materials and Technology 143, no. 1 (2020). http://dx.doi.org/10.1115/1.4047744.

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Abstract This paper aims to present an integrated multi-scale method for predicting the anisotropic and nonlinear elasto-plastic behavior of short glass fiber-reinforced polymer (GFRP) materials typically produced by injection molding. The proposed method combines injection molding and microstructure together, with considering the nonaligned fibers and their corresponding anisotropy, to semi-analytically estimate the local effective mechanical properties at every point of GFRP. Micro-computed tomography measurement and injection molding simulation are used to obtain the fiber orientation tensor. The two-step mean-field homogenization method is applied to calculate the mechanical behaviors of the PA66GF30 GFRP with distributed-orientation fibers based on the fiber orientation tensor. Reverse engineering is used to obtain the optimized parameters of J2-plasticity and Tsai-Hill three-dimensional transversely isotropic stain-based failure criterion. Moreover, the integral mapping method can complete the transformation of the fiber orientation tensor from injection simulation to structure simulation model. The proposed integrated approach with the optimized parameters is verified by predicting the ring samples’ behavior from injection plates. The results from this investigation are expected to provide some design guidelines for GFRP composites.

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Pise, Mangesh, Dominik Brands, Gregor Gebuhr, Mohammad Sarhil, Jörg Schröder, and Steffen Anders. "Elasto‐plastic phase‐field model for pullout tests of steel fiber embedded in high‐performance concrete: numerical calibration and experimental validation." PAMM 19, no. 1 (2019). http://dx.doi.org/10.1002/pamm.201900255.

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AlBahrani, Hussain, Euripides Papamichos, and Nobuo Morita. "Building an Integrated Drilling Geomechanics Model Using a Machine-Learning-Assisted Poro-Elasto-Plastic Finite Element Method." SPE Journal, May 1, 2021, 1–21. http://dx.doi.org/10.2118/205497-pa.

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Summary The petroleum industry has long relied on predrilling geomechanics models to generate static representations of the allowable mud weight limits. These models rely on simplifying assumptions such as linear elasticity, a uniform wellbore shape, and generalized failure criteria to predict failure and determine a safe mud weight. These assumptions lead to inaccurate results, and they fail to reflect the effect of different routing drilling events. Thus, this paper’s main objective is to improve the process for predicting the wellbore rock failure while drilling. This work overcomes the limitations by using a new and integrated modeling scheme. Wellbore failure prediction is improved through the use of an integrated modeling scheme that involves an elasto-plastic finite element method (FEM) model, machine learning (ML) algorithms, and real-time drilling data, such as image logs from a logging while drilling (LWD) tool that accurately describes the current shape of the wellbore. Available offset well data are modeled in the FEM code and are then used to train the ML algorithms. The produced integrated model of FEM and ML is used to predict failure limits for new wells. This improved failure prediction can be updated with the occurrence of different drilling events such as induced fractures and wellbore enlargements. The values are captured from real-time data and reflected in the integrated model to produce a dynamic representation of the drilling window. The integrated modeling scheme was first applied to laboratory experimental results to provide a proof of concept and validation. This application showed improvement in rock-failure prediction when compared with conventional failure criteria such as Mohr-Coulomb. Also, offset-well data from wireline logging and drilling records are used to train and build a field-based integrated model, which is then used to show that the model output for a separate test well reasonably matches the drilling events from the test well. Application of this integrated model highlights how the allowable mud-weight limits can vary because drilling progresses in a manner that cannot be captured by the conventional predrilling models. As illustrated by a field case, the improvement in failure prediction through this modeling scheme can help avoid nonproductive time events such as wellbore enlargements, hole cleaning issues, pack-offs,stuck-pipe, and lost circulation. This efficiency is to be achieved by a real-time implementation of the model where it responds to drilling events as they occur. Also, this model enables engineers to take advantage of available data that are not routinely used by drilling.

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Journal articles on the topic 'Elasto-plastic validation'

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