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Calibration of isotropic hardening parameters (a) saturation of the isotropic hardening variables, and (b) increase of the saturated isotropic hardening variables.
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The ability to model the cyclic behavior of low yield point steel accurately is essential for its application to seismic design. In this study, uniaxial tests of monotonic and strain controlled cyclic loading are conducted to investigate the mechanical properties of the low yield point steel BLY160. As observed in the test, work-hardening is an imp...
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In this study, a finite cyclic elasto-plastic constitutive model is developed to simulate the cyclic hardening and softening of the low-yield-point steel BLY160. Compared with existing models, an improved description of the stress-strain hysteresis loops is achieved by introducing a modified Chaboche kinematic hardening rule and a nonlinear isotrop...
We presented an elastic-plastic endochronic constitutive model of 0Crl7Ni4Cu4Nb stainless steel based on the plastic endochronic theory (which does not need the yield surface) and experimental stress-strain curves. The key feature of the model is that it can precisely describe the relation of stress and strain under various loading histories, inclu...
SANISAND-MSf is one the latest members of the SANISAND family of models within a critical state compatible bounding surface plasticity framework with kinematic hardening of the yield surface. In pursuance of enhancing the undrained cyclic response, the model incorporates a memory surface for controlling the stiffness affecting the deviatoric and vo...
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This paper focuses on the effect of loading history on the ratcheting behavior and stress–strain hysteresis loops under uniaxial loading. A nonlinear constitutive model for cyclic elastoplastic behavior of metals is developed in the rate-independent framework of small deformation plasticity theory. The effect of applied loading history on plastic m...
Correct determination of ratcheting strain is very important in cyclic loading. A new simple yield surface distortion model is presented and its effect on cyclic loading and ratcheting prediction is investigated in this research. Model of Baltov and Sawczuk was modified in order to be able to consider directional distortion of the yield surface. Mo...
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... One of the reasons of the excessive complexity stands in the historydependent behaviors which require the reconstruction of the whole past history [9][10][11][12][13][14]. Indeed, when this is combined with fine spatial meshes and very long time horizons, the computational complexity leads to veloped in [17][18][19][20][21][22], where the computational time is reduced via an interpolation of the solution at different time scales. ...
Within the framework of computational plasticity, recent advances show that the quasi-static response of an elasto-plastic structure under cyclic loadings may exhibit a time multiscale behavior. In particular, the system response can be computed in terms of time microscale and macroscale modes using a weakly intrusive multi-time Proper Generalized Decomposition (MT-PGD). In this work, such micro-macro characterization of the time response is exploited to build a data-driven model of the elasto-plastic constitutive relation. This can be viewed as a predictor-corrector scheme where the prediction is driven by the macrotime evolution and the correction is performed via a sparse sampling in space. Once the nonlinear term is forecast, the multi-time PGD algorithm allows the fast computation of the total strain. The algorithm shows considerable gains in terms of computational time, opening new perspectives in the numerical simulation of history-dependent problems defined in very large time intervals.
... A comprehensive study about this field can be found in Refs. [4][5][6][7][8]. In a classical singlesurface cyclic plasticity theory, the specific yield criteria and flow rule must be given to define the occurrence of yield and the evolution of plastic strain. ...
... During plastic deformation, the elastic modulus sharply decreases to a stable value with the accumulation of plastic strain. The natural exponential function originally proposed by Yoshida [43] is employed to describe the evolution of elastic modulus as shown in Eq. (8), where E 0 is the initial elastic modulus in the monotonic tensile phase, E sat is the saturation value, ξ E is the material parameter that controls the evolution rate. ...
... In the original memory surface model, only expansion and translation of the surface were admitted, i.e., only the historical maximum amplitude was considered with ignoring the effect of the current strain range, which was not appropriate for the descendant amplitude loading cases. Some researchers introduced the shrinkage of the memory surface with complete evanescence effects (or complete collapse effects [38]), where only the current amplitude was considered ignoring the role of the historical maximum amplitude [8,44]. To consider the incomplete evanescence effect, the evolution equations of ζ and q were proposed by Nouailhas [45] as follows. ...
A R T I C L E I N F O Keywords: Constitutive model Numerical integration algorithm Stainless steel Strain memory effect Unsaturated cyclic hardening/softening A B S T R A C T To predict seismic behavior of steel structures and conduct performance-based seismic design, a precise constitutive model to accurately reflect the elastic-plastic response of structural steel under various loading protocols is always needed, so that the strength, deformation capacity, and energy dissipation capacity of a steel component or system in case of a severe earthquake can be reasonably evaluated. On the other hand, the constitutive model should be convenient for practical engineering implementation and application. Previous studies show that certain type steel like stainless steel S30408 shows complex features under various strain ranges such as pronounced strain memory effect, unsaturated cyclic softening/hardening under small/large strain amplitudes, which differ from mild steel and low yield point steel. Therefore, the stainless steel S30408 is taken as the research object in this study to develop a new constitutive model to describe structural steels with such complex mechanical properties. First, a new nonlinear isotropic and kinematic hardening rule is extended based on the classical Chaboche model and a functional relationship between the hardening rate (defined as the variation value of peak stress in every adjacent cycle during cyclic loading) and the applied strain amplitude is established through a logistics function to describe the coupling effects. Second, the numerical implementation technique for three-dimensional is elaborated in detail. Third, the numerical implementation technique is extended to plane stress cases by the improved P projection method. Using the numerical integration algorithm, the proposed constitutive model can be successfully incorporated into ABAQUS/Standard through the UMAT subroutine interface which is suitable for both solid and shell elements.
... Although the strain amplitudes of some cycles of the constant and varying strain loading were the same, the corresponding peak stresses were mostly quite different, as reflected by the comparisons of the markers and dashed lines in the same colour (corresponding to the same strain amplitudes) in Fig. 20. An exception to this was LP6, for which the peak stresses at the strain amplitudes of ±1% and ±2% were similar to those under the corresponding constant strain amplitudes, indicating that the initial small strain amplitudes (see Fig. 7) had a negligible influence on the peak stresses [35,44,45]. Overall, the cyclic peak stresses of WAAM steel are not only dependent on the current strain amplitude but also on the strain history. ...
Wire arc additive manufacturing (WAAM) is an efficient and cost-effective method of metal 3D printing that is well suited to structural engineering applications. Fundamental test data on the mechanical properties of WAAM materials, especially under cyclic loading, are however lacking. To address this, an experimental study into the cyclic behaviour of WAAM steel plates has been undertaken and is reported herein. Following geometric and quasi-static mechanical characterisation, a total of 40 as-built and machined coupons were tested under different cyclic loading protocols. Key results from the tests, including the full hysteresis curves, are presented and discussed. A cyclic constitutive model allowing for a yield plateau and the degradation of elastic modulus is proposed and validated against the test data. It is shown that the examined WAAM steel exhibited cyclic hardening behaviour dependent on the strain amplitude and strain history. The elastic modulus of the WAAM material was found to decrease in the first few cycles and then remain stable with increasing accumulated plastic strain. Good energy dissipation performance was also observed, indicating the potential of WAAM steels for seismic applications. 2
... Zhang et al. [3] investigated the dynamic effects on the cyclic behaviors of LYP100 shear panel damper and proposed the linear strain-hardening analytical model for better description under dynamic random wave. Xu et al. [4][5][6] performed the experimental and modeling studies of the cyclic hardening and softening behaviors in terms of the BLY160 steel and the shear panel dampers. Wang et al. [7] experimentally investigated the monotonic as well as cyclic behaviors of SLY100 steel and developed the combined hardening constitutive model to simulate the buckling-restrained brace (BRB) made of SLY100 steel. ...
This paper presents the experimental and modeling studies of the ductile fracture initiation of LYP225 steel, considering the stress state and loading history dependency. The monotonic material tests, including the notched round bars (NRBs), flat grooved plates (FGPs), and the shear plates (SPs), confirm the prominent stress state dependency of the ductile fracture. The increased stress triaxiality will significantly reduce the fracture strain, and the shear effect quantified by the Lode angle parameter will degrade the deformability under similar triaxiality. The Hosford-Coulomb fracture criterion can well characterize the relationship between fracture strain and stress state variables. Regarding the cyclic loading, a generalized expression of the cutoff region is proposed to consider the temporarily frozen damage accumulation under compression applied. In addition, the premature cyclic fracture initiation predicted by the monotonic fracture criterion highlights the necessity of considering the loading history effect. Based on the plastic strain memory surface, a reduced factor is introduced for the lower damage accumulation rate under cyclic loading. By comparing the testing and predicted plastic deformation corresponding to fracture initiation, the proposed fracture model is validated under different stress states and loading protocols, as indicated by the low average percentage errors of 4.02% for monotonic loading and 16.7% for cyclic loading.
... Meanwhile, the previous studies indicate that the cyclic hardening or softening behavior depended not only on the material but also on the magnitude of the applied loading (stress/strain amplitude) and the loading path (pre-stressing/pre-cycling) [13][14][15]. Moreover, Xu, Nie, Fan, Tao, and Ding [16] observed in the LCF test on BLY160 that work-hardening is an essential hysteresis property concerning the energy dissipation of the steel. However, as plastic strain accumulates, a "flatting effect" occurs, i.e., cyclic softening in both stiffness and stress. ...
... Materials 2023, 16,6326 15 of 19 ...
To study the fatigue failure and microstructure evolution behavior of SS304, low-cycle fatigue tests are conducted at room temperature (RT), 300 °C, and 650 °C. The results indicate that, because of the influence of the dislocation walls, carbon-containing precipitates, and deformation twins, the cyclic hardening behavior is presented at RT. However, different from the cyclic hardening behavior at RT, the cyclic softening behavior of SS304 can be observed due to the dynamic recovery and recrystallization containing dislocation rearrangement and annihilation at 300 °C and 650 °C. In addition, two fatigue crack initiation modes are observed. At RT, the single fatigue crack initiation mode is observed. At high temperatures, multiple crack initiation modes are presented, resulting from the degradation of material properties. Furthermore, a new fatigue life prediction model considering the temperature is conducted as a reference for industrial applications.
... In general, the simulation of cyclic hardening/softening behavior often involves incorporating an isotropic hardening rule (Xu et al., 2016), which describes the expansion of the yield surface. Following this approach, the experiment and simulation of the maximum stress evolution and hysteresis loops at typical strain amplitude of ±0.6% are presented in Fig. 16. ...
... One of the reasons of the excessive complexity stands in the history-dependent behaviours which require the reconstruction of the whole past history [3,4,5,6,7,8]. Indeed, when this is combined with fine spatial meshes and very long time horizons, the computational complexity leads to cost-prohibitive simulations and to the necessity of adopting suitable simplified models. ...
Within the framework of computational plasticity, recent advances show that the quasi-static response of an elasto-plastic structure under cyclic loadings may exhibit a time multiscale behaviour. In particular, the system response can be computed in terms of time microscale and macroscale modes using a weakly intrusive multi-time Proper Generalized Decomposition (MT-PGD). In this work, such micro-macro characterization of the time response is exploited to build a data-driven model of the elasto-plastic constitutive relation. This can be viewed as a predictor-corrector scheme where the prediction is driven by the macrotime evolution and the correction is performed via a sparse sampling in space. Once the nonlinear term is forecasted, the multi-time PGD algorithm allows the fast computation of the total strain. The algorithm shows considerable gains in terms of computational time, opening new perspectives in the numerical simulation of history-dependent problems defined in very large time intervals.
... However, it is interesting to note that master curve could not be constructed. Hence, they analyzed the Masing/non-Masing behavior of 304L SS and 12 other materials from the literature [5,6] and found that the construction of the master curve was not possible for two other materials (BLY160 steel and AISI 321) [7,8]. Thus, Yadav et al. [5,6] highlighted that there are materials for which the construction of the master curve may not be possible and classified the non-Masing behavior into two categories based on the possibility of master curve construction; in Type-I ( Fig. 1(c)), the master curve can be constructed, while in Type-II ( Fig. 1(d)), the master curve can not be constructed. ...
... in 2021, no data or information related to the internal material/microstructural changes is available in the open literature.Although other researchers have not identified the Type-II non-Masing behavior, the analysis of the published data in the open literature suggests that several materials like-304L SS[6], BLY160 steel[7], ...
... Numerous studies have been conducted to clarify the cyclic plasticity and low-cycle fatigue properties of different structural metals, including low-yield-point (LYP) structural steels, mild structural steels (MS), highstrength structural steels (HSS), stainless steels and SC bimetallic steels. With regard to LYP steels, cyclic loading experiments on LYP100, LYP160, LYP225 and BLY160 steels were conducted respectively by Shi et al. [21], Yang et al. [22], Wang et al. [23] and Xu et al. [24]. Based upon the experimental results, the prediction models for fatigue life, cyclic skeleton curves and cyclic stress-strain curves are calibrated, modified and validated. ...
... (1)∼(3) indicate that the yield criterion and the hardening laws that control the evolution of internal variables can all be manipulated. Most classic elastoplastic constitutive models use mathematical regression to formulate special hardening laws that reproduce coupon test results [55]. For instance, the elastoplastic model of structural steel proposed in [56] developed the external Chaboche-Voce combined hardening framework and the internal "incomplete collapse effect of the memory surface" concept based on experimental observations that the trends of cyclic hardening or softening resembled exponential functions. ...
... Secondly, most static feature studies are interested in mechanical properties such as material strengths, structural loading capacities, and maximal interstory drift ratios. However, these mechanical properties are closely related to loading paths, which can experience strengthening or softening induced by cyclic loads [55,56], thereby affecting the results. Therefore, most static feature studies can be seen as simplified models that neglect the influence of loading path dependence. ...
With the informatization of the building and infrastructure industry, conventional analysis methods are gradually proving inadequate in meeting the demands of the new era, such as intelligent synchronization and real-time simulation. Artificial intelligence (AI) technology has emerged as a promising alternative due to its high expressiveness, efficiency, and scalability. This has given rise to a new research field of AI-based computation in civil engineering. In this study, a state-of-the-art review of the research on material and structural analyses using AI technology in civil engineering was performed to provide a general introduction to the current progress. The research was classified into static feature studies, dynamic feature studies, and composite feature studies according to the problem inputs. The general methodology, commonly used AI models, and representative applications of each research category were elaborated. On these bases, the strengths and weaknesses of current studies were discussed. To demonstrate the accuracy and efficiency of AI models in comparison with conventional numerical methods, a concrete example of an end-to-end deep learning framework for structural analysis was highlighted. Finally, we suggested four open problems from the perspective of engineering applications, indicating the major challenges and future research directions regarding AI-based computational analysis in civil engineering.
