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【新文速递】2024年9月8日固体力学SCI期刊最新文章

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今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 2 篇,Thin-Walled Structures 4 篇

International Journal of Solids and Structures

Energy absorption of Kresling pattern thin-walled structures with pre-folded patterns and graded stiffness

Xiaolei Wang, Haibo Qu, Buqin Hu, Haoqian Wang, Wenju Liu, Sheng Guo

doi:10.1016/j.ijsolstr.2024.113057

具有预折叠图样和梯度刚度的Kresling薄壁结构的能量吸收

Traditional thin-walled structures are widely employed in several energy-absorbing engineering fields, and origami patterns inspire novel structures with unique functionalities in this area. In this study, we explore energy-absorbing effects of origami-inspired thin-walled structures from perspective of the predicted stability of the Kresling origami. Our research utilizes finite element analysis and experimental validation to evaluate and contrast the energy-absorbing effects of the Kresling origami-inspired thin-walled structures (KOI-TWSs) with a traditional hexagonal thin-walled structure (HTWS). The results indicate that introducing the Kresling origami pattern into the thin-walled structure to obtain geometric defects (pre-folded pattern) and graded stiffness, and their effects are reflected in improving the buckling deformation stability or reducing the initial peak force. These effects depend on the predicted stability of the Kresling origami and are intuitively reflected in the geometric parameters. On the other hand, the reusability of materials is worth considering for improving the energy absorption of the thin-walled structures. These works provide new contents and perspectives for the KOI-TWSs.

传统薄壁结构广泛应用于吸能工程领域,折纸图案激发了具有独特功能的新型结构。在本研究中,我们从Kresling折纸的预测稳定性角度探讨了折纸启发薄壁结构的吸能效应。本研究利用有限元分析和实验验证对Kresling折纸薄壁结构(KOI-TWSs)和传统六边形薄壁结构(HTWS)的吸能效果进行了评价和对比。结果表明,在薄壁结构中引入Kresling折纸图案可获得几何缺陷(预折叠图案)和梯度刚度,其作用体现在提高屈曲变形稳定性或降低初始峰值力上。这些影响取决于克雷斯林折纸的预测稳定性,并直观地反映在几何参数中。另一方面,为了提高薄壁结构的吸能,材料的可重复使用性值得考虑。这些工作为KOI-TWSs提供了新的内容和视角。


Mechanics of Materials

Correlation between the ratio between the tensile and shear yield strength on porosity evolution in isotropic ductile materials

Karl R. Knaak, Oana Cazacu, Benoit Revil-Baudard

doi:10.1016/j.mechmat.2024.105150

各向同性韧性材料抗拉屈服强度与抗剪屈服强度之比与孔隙度演化的关系

In this paper, we investigate the dilatational response of porous solids with matrix plastic behavior governed by Cazacu (2018) yield criterion that involves both invariants of the stress deviator, the relative weight of these invariants being described by a parameter . This parameter depends only on the ratio  between the shear and tensile strengths; for  = 0,  =  and the von Mises criterion is recovered. For both compressive and tensile loadings, FE unit-cell simulations were conducted at fixed stress triaxialities and various ordering of the principal stresses, namely loadings such that  = 0 and axisymmetric loadings such that  > 0 and  < 0, respectively. Irrespective of the material’s  ratio, there is a combined effect of the sign of the mean stress and  on the dilatational response. The value of the ratio  dictates the rate at which the porosity evolves. Under axisymmetric tensile loadings, for a material with  <  the rate of void growth is faster than for a porous von Mises material, the reverse holds true for a material with  > . For axisymmetric compressive loadings, the larger is the  ratio of the material, the slower is the rate at which porosity closes. For loadings at  = 0 materials with  <  exhibit slower rate of void growth or void collapse than for axisymmetric loadings, the opposite being true for materials with  > .

在本文中,我们研究了具有基体塑性行为的多孔固体的膨胀响应,该响应受Cazacu(2018)屈服准则的约束,该准则涉及应力偏差的两个不变量,这些不变量的相对权重由参数描述。该参数仅取决于剪切强度与拉伸强度之比;为= 0,=,恢复von Mises判据。对于压缩和拉伸加载,有限元单元格模拟分别在固定应力三轴性和不同主应力顺序下进行,即加载= 0和轴对称加载> 0和< 0。无论材料的比例如何,平均应力的符号和膨胀响应都有共同的影响。比值的值决定了孔隙度演化的速率。在轴对称拉伸载荷下,孔隙生长速率<的材料比多孔的von Mises材料更快,而>的材料则相反。对于轴对称压缩载荷,材料的比例越大,孔隙率闭合的速度越慢。对于= 0加载,<的材料表现出比轴对称加载更慢的空穴生长或空穴塌陷速率,>的材料则相反。


International Journal of Plasticity

Tailoring Mechanical Properties of Pearlitic Steels through Size Regulation of Multiscale Microstructures: Experiments and Simulations

Xutao Huang, Yinping Chen, Jianjun Wang, Wenxin Wang, Gang Lu, Sixin Zhao, Qian Li, Yujie Liu, Chunming Liu

doi:10.1016/j.ijplas.2024.104110

珠光体钢多尺度显微组织尺寸调节的机械性能:实验与模拟

Pearlitic steels possess excellent mechanical properties due to their multiscale microstructures, yet this configuration introduces complex size and interface effects, impeding the elucidation of their microscopic deformation mechanisms. In this study, a predictive framework that combines a high-resolution reconstruction algorithm with a strain gradient crystal plasticity model was developed to investigate the relationship between local deformation behaviors in nodules, colonies, and lamellae of various sizes and their mechanical properties. This approach effectively reconstructs the multiscale structure of pearlite and accurately tracks the dynamic mechanical responses. The integrated experimental and computational findings highlight the critical role of microstructure size in regulating strain delocalization and dislocation dynamics, which, through strain partitioning and interface density, are vital for optimizing mechanical properties. Notably, a decrease in lamellar spacing and nodule size significantly enhances both strength and toughness, while smaller nodules and colonies promote increased plasticity. Finally, a dual-parameter Hall-Petch equation incorporating lamellar spacing and nodule size is introduced, enabling precise quantification of the impact of all microstructures in pearlite on mechanical properties with robust predictive capabilities.

珠光体钢由于其多尺度微观结构而具有优异的力学性能,但这种结构引入了复杂的尺寸和界面效应,阻碍了其微观变形机制的阐明。本研究开发了一个结合高分辨率重建算法和应变梯度晶体塑性模型的预测框架,以研究不同尺寸的结核、菌落和片层的局部变形行为与其力学性能之间的关系。该方法有效地重建了珠光体的多尺度结构,准确地跟踪了动态力学响应。综合实验和计算结果强调了微观结构尺寸在调节应变离域和位错动力学方面的关键作用,这些作用通过应变分配和界面密度对优化力学性能至关重要。值得注意的是,减少片层间距和结核尺寸可显著提高强度和韧性,而较小的结核和集落可提高塑性。最后,引入了包含片层间距和结核尺寸的双参数Hall-Petch方程,可以精确量化珠光体中所有微观结构对力学性能的影响,并具有强大的预测能力。


Atomistic analysis of the mechanisms underlying irradiation-hardening in Fe–Ni–Cr alloys

A. Ustrzycka, F.J. Dominguez-Gutierrez, W. Chromiński

doi:10.1016/j.ijplas.2024.104118

Fe-Ni-Cr合金辐照硬化机理的原子分析

This work presents a comprehensive examination of the physical mechanisms driving hardening in irradiated face-centered cubic FeNiCr alloys. The evolution of irradiation-induced defects during shear deformation is modeled by atomistic simulations through overlapping cascade simulations, where the nucleation and evolution of dislocation loops is validated by transmission electron microscopy images obtained from irradiated FeNiCr alloys using tandem accelerator. The effect of different shear rates on the microstructure of irradiated materials with a specific focus on the changes in the density of voids and dislocation loops induced by irradiation was analyzed. Additionally, the fundamental interaction processes between single irradiation-induced defects contributing to irradiation hardening, such as voids and dislocation loops in the alloy are explained. The analysis at atomic level indicates that both the dislocation loops and the voids exhibit strengthening effects. Furthermore, the nanometric voids are much stronger obstacles than dislocation loops of comparable size. The mechanism of cutting the voids leads to an increase of voids density and thus contributes to an increase in irradiation hardening. The mechanism of collapse of small voids into dislocation loops leads to decrease of voids density and at the same time increase of loops density. The coupling effect between the density of voids and dislocation loops is determined. Finally, the novel, physical mechanisms-based model of irradiation hardening and dislocation-radiation defect reaction kinetics are developed, which consider the mechanisms of void cutting, void shrink and void collapse to dislocation loop.

这项工作提出了一个全面的物理机制驱动硬化在辐照面心立方FeNiCr合金。在剪切变形过程中,辐照诱导缺陷的演变通过重叠级联模拟的原子模拟来模拟,其中位错环的成核和演变通过使用串联加速器从辐照FeNiCr合金中获得的透射电子显微镜图像来验证。分析了不同剪切速率对辐照材料微观结构的影响,重点分析了辐照引起的空洞和位错环密度的变化。此外,还解释了导致辐照硬化的单一辐照缺陷(如合金中的空洞和位错环)之间的基本相互作用过程。在原子水平上的分析表明,位错环和空洞都表现出强化作用。此外,纳米级的空洞比同等尺寸的位错环具有更强的障碍。切割孔洞的机制导致孔洞密度增加,从而导致辐照硬化的增加。小孔洞坍缩成位错环的机制导致孔洞密度减小,同时导致位错环密度增大。确定了孔隙密度与位错环之间的耦合效应。最后,建立了基于物理机制的辐照硬化和位错-辐射缺陷反应动力学模型,该模型考虑了空穴切削、空穴收缩和空穴坍缩到位错环的机理。


Thin-Walled Structures

Theoretical study of extracting modal frequencies and hinge joint stiffness for thin-walled assembled multi-girder bridges from 3D vehicle

Baoquan Wang, Yan Zeng, Dongming Feng

doi:10.1016/j.tws.2024.112429

薄壁拼装多梁桥三维车辆模态频率和铰节点刚度提取的理论研究

This paper presents a theoretical framework for extracting the modal frequencies of thin-walled assembled multi-girder bridges (AMGBs), which are widely adopted in small- and medium-span highway bridges, using the dynamic response of a three-dimensional (3D) moving vehicle. For the first time, closed-form solutions for the responses of the bridge and contact point (CP) are derived when the test vehicle passes through the AMGB. Based on the derived CP response, a guiding procedure for retrieving the modal frequency and hinge joint stiffness of the bridge is proposed. The correctness of the analytical solutions for the CP response and the reliability of the bridge frequency identification are verified through numerical examples. Additionally, the robustness of the proposed technique is examined under various influence factors. The results show that maintaining a moderate vehicle speed can balance the accuracy and efficiency of the bridge frequency identification. The damping of vehicle tires has a small effect on frequency extraction using the CP response, while an increase in bridge damping ratio diminishes the visibility of its frequencies. Nevertheless, for the investigated bridge damping ratios, the effectiveness remains satisfactory, as the first four frequencies still being discernible. The residual contact response of the front and rear wheels can effectively eliminate the masking effect of pavement roughness, thereby enhancing the frequency extraction effect. Furthermore, the proposed method exhibits strong robustness against measurement noise.

本文提出了一种基于三维运动车辆动力响应的薄壁拼装多梁桥模态频率提取的理论框架。薄壁拼装多梁桥在中小跨公路桥梁中得到广泛应用。首次推导了试验车辆通过AMGB时桥梁和接触点(CP)响应的封闭解。基于推导出的CP响应,提出了一种检索桥梁模态频率和铰节点刚度的指导程序。通过算例验证了CP响应解析解的正确性和桥梁频率识别的可靠性。此外,在各种影响因素下检验了所提出技术的鲁棒性。结果表明,保持适度车速可以平衡桥梁频率识别的准确性和效率。车辆轮胎阻尼对利用CP响应提取频率的影响较小,而桥梁阻尼比的增加会降低其频率的可见性。然而,对于所研究的桥梁阻尼比,有效性仍然令人满意,因为前四个频率仍然是可识别的。前后轮残余接触响应可以有效消除路面粗糙度的掩蔽效应,从而增强频率提取效果。此外,该方法对测量噪声具有较强的鲁棒性。


Seismic performance of ultra-high performance concrete-filled FRP tube composite columns reinforced with SFCBs: Test and modeling

Zhiwen Zhang, Ashraf Ashour, Wenjie Ge

doi:10.1016/j.tws.2024.112430

sfcb加固超高性能FRP混凝土筒复合柱抗震性能试验与建模

To reduce residual deformation and address corrosion issues, this paper introduces a novel type of composite columns, utilizing ultra-high performance concrete (UHPC)-filled fiber reinforced polymer (FRP) tubes (UHPC-FFT) and reinforced with steel-FRP composite bars (SFCBs). The seismic performance of the proposed SFCB-reinforced UHPC-FFT composite columns was evaluated through pseudo-static experiments and numerical analysis in comparison with those of traditional composite columns. Results indicated that the UHPC-FFT composite columns reinforced with SFCB exhibited larger energy dissipation compared with those reinforced with either steel or FRP bars. Increasing the axial compression ratio from 0.15 to 0.25 enhance load-bearing capacity but reduces ductility and energy dissipation. Increasing the yield strength of internal steel bar of SFCBs can improve the load-bearing capacity and deformation of the columns without affecting the ductility, initial stiffness, and stiffness degradation rate. Increasing the elastic modulus of out-wrapped FRP of SFCBs enhanced the seismic performance of UHPC-FFT composite columns but could lead to premature failure due to FRP rupture. It is recommended to set an elastic modulus for the outer FRP wrap at 55 GPa for optimal seismic performance in UHPC-FFT composite columns.

为了减少残余变形和解决腐蚀问题,本文介绍了一种新型的复合柱,利用超高性能混凝土(UHPC)填充纤维增强聚合物(FRP)管(UHPC- fft)和钢-FRP复合筋(SFCBs)加固。通过拟静力试验和数值分析,与传统组合柱的抗震性能进行了比较,评价了所提出的sfcb - UHPC-FFT组合柱的抗震性能。结果表明:SFCB加筋的UHPC-FFT组合柱比钢筋和FRP筋的组合柱耗能更大;将轴压比由0.15提高到0.25,可提高承载能力,但会降低延性和耗能。提高sfcb内钢筋屈服强度可以在不影响延性、初始刚度和刚度退化率的情况下提高柱的承载能力和变形量。提高sfcb外包FRP的弹性模量,提高了UHPC-FFT复合柱的抗震性能,但可能导致FRP断裂而过早破坏。为使UHPC-FFT复合柱抗震性能最佳,建议将FRP外膜弹性模量设置为55gpa。


Local buckling and capacities of stainless steel hexagonal hollow sections under axial compression

Yukai Zhong, Ke Jiang, Andi Su, Jiyang Fu, Airong Liu, Ou Zhao

doi:10.1016/j.tws.2024.112431

不锈钢六角形空心截面在轴压作用下的局部屈曲和承载力

This paper presents experimental and numerical investigations into the local buckling behaviour and capacities of stainless steel hexagonal hollow sections. A testing programme, including tensile coupon tests, initial local geometric imperfection measurements and fifteen stub column tests, was firstly carried out. The key test results, including failure loads, load–end shortening curves and failure modes, were reported. Subsequently, a numerical modelling programme was conducted, where finite element models were developed and validated against the test results and then used to conduct parametric studies to generate additional numerical data. The obtained test and numerical data were used to evaluate the relevant local buckling design rules specified in the European code, American specification and ASCE standard. The evaluation results revealed that the slenderness limits, as defined in the European code and American specification, were generally accurate and safe when used for cross-section classification of stainless steel hexagonal hollow sections, while the ASCE slenderness limit was unsafe. The European code and American specification resulted in overall accurate and consistent cross-section compression resistance predictions, but the predictions for non-slender cross-sections were conservative and scattered, due to the neglect of material strain hardening. The ASCE standard led to overall scattered and relatively conservative cross-section compression resistance predictions, but also with some unsafe predictions for those intermediate cross-section sizes due mainly to the unsafe slenderness limit. Finally, a revised ASCE design approach was proposed and shown to result in more accurate predictions of cross-section classification and resistances.

本文对不锈钢六角空心截面的局部屈曲行为和屈曲能力进行了实验和数值研究。首先进行了一套测试程序,包括张轴试验、初始局部几何缺陷测量和15根短柱试验。报告了主要试验结果,包括破坏荷载、荷载-端缩短曲线和破坏模式。随后,进行了数值模拟程序,其中开发了有限元模型,并根据测试结果进行验证,然后用于进行参数研究,以生成额外的数值数据。利用所获得的试验和数值数据,对欧洲规范、美国规范和ASCE标准中有关的局部屈曲设计规则进行了评价。评价结果表明,欧洲规范和美国规范定义的长细限值用于不锈钢六角形空心截面分类时,总体上是准确和安全的,而ASCE长细限值则不安全。欧洲规范和美国规范对截面抗压抗力的预测总体上是准确一致的,但对非细长截面的预测由于忽略了材料的应变硬化而较为保守和分散。ASCE标准对截面抗压性能的预测总体上较为分散和保守,但对中间截面尺寸的预测也存在一定的不安全,主要是由于长细限值的不安全。最后,提出了一种改进的ASCE设计方法,并证明该方法可以更准确地预测截面分类和阻力。


Fatigue test and evaluation of U-rib butt welds in orthotropic steel decks

Dengke Zhang, Chuang Cui, Shijin Qiu, Qinghua Zhang, Ye Lu

doi:10.1016/j.tws.2024.112432

正交各向异性钢甲板u形肋对接焊缝疲劳试验与评价

U-rib butt weld cracking is one of the most typical fatigue failure modes of orthotropic steel decks (OSDs), which directly endangers the safety of bridges. Since the on-site quality of butt welds is difficult to guarantee, manufacturing defects are an important factor affecting fatigue performance. A full-scale OSD section specimen was manufactured with a real process, and the force characteristics and fatigue stress history of U-rib butt welds were investigated, and the fatigue crack growth characteristics were analyzed. A finite element model (FEM) was developed to extract the structural stress components of typical failure modes, and the equivalent structural stress method was used to quantify the effect of manufacturing defect sizes on the failure modes and fatigue life of U-rib butt welds. The results showed that the fatigue strength of U-rib butt welds was evaluated to be 125.1 MPa (corresponding to 4.6 million load cycles) using the equivalent structural stress method. When the radius of defect R < 1.25 mm, the fatigue cracking mode is weld toe cracking; when R > 1.25 mm, the fatigue cracking mode is internal defect cracking, which has a significant effect on the fatigue life.

u型肋对接焊缝开裂是正交各向异性钢桥面最典型的疲劳破坏形式之一,直接危及桥梁的安全。由于对接焊缝的现场质量难以保证,制造缺陷是影响疲劳性能的重要因素。采用真实工艺制作了全尺寸OSD截面试样,研究了u肋对接焊缝的受力特性和疲劳应力历史,并分析了其疲劳裂纹扩展特征。建立有限元模型,提取典型失效模式的结构应力分量,采用等效结构应力法量化制造缺陷尺寸对u肋对接焊缝失效模式和疲劳寿命的影响。结果表明:采用等效结构应力法计算u肋对接焊缝的疲劳强度为125.1 MPa(对应460万次载荷循环);当缺陷半径R < 1.25 mm时,疲劳开裂方式为焊趾开裂;当R > 1.25 mm时,疲劳开裂方式为内部缺陷开裂,对疲劳寿命影响显著。


来源:复合材料力学仿真Composites FEM
ACTMechanicalHPCInspireDeform疲劳断裂电子ADS裂纹理论化机材料多尺度试验
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【新文速递】2024年9月11日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 2 篇,Thin-Walled Structures 1 篇International Journal of Solids and StructuresTowards a rational approach for multi-axial experimental campaigns for rubberlike materialBenjamin Martin, Erwan Verron, Michel Coret, Nathan Sellesdoi:10.1016/j.ijsolstr.2024.113060探讨类橡胶材料多轴实验运动的合理方法This work takes up the developments around the logarithmic strain tensor and uses the invariants of this tensor to propose a new approach to multi-axiality of fatigue experiments for elastomers. This study leads to the introduction of a new notion, modality, which is intended as the microscopic counterpart of uni- and multi-axiality. This notion is quantified by the K3 invariant (mode of deformation) of the logarithmic strain tensor, and is used to rationalize tension-torsion experimental campaigns. It is illustrated using two examples: the perfect cylinder and the AE2 “diabolo” sample. We then propose a methodology for building a test campaign based on this new definition.这项工作围绕对数应变张量展开,并利用该张量的不变量提出了弹性体疲劳实验多轴性的新方法。这项研究引入了一个新概念--模态,作为单轴性和多轴性的微观对应概念。该概念通过对数应变张量的 K3 不变式(变形模式)进行量化,并用于合理解释拉伸-扭转实验活动。我们用两个例子对其进行了说明:完美圆柱体和 AE2 “空竹”样品。然后,我们提出了基于这一新定义的试验方法。Journal of the Mechanics and Physics of SolidsA covariant formulation for finite strain modelling of orthotropic elasticity and orthotropic plasticity with plasticity-induced evolution of orthotropy: Application to natural fibresChristian C. Celigoj, Manfred H. Ulzdoi:10.1016/j.jmps.2024.105846具有塑性诱导正交异性演化的正交异性弹性和正交异性塑性有限应变模型的协变公式:在天然纤维中的应用We introduce a rate-independent model for orthotropic elastic and orthotropic plastic material behaviour in a hyper-elasto-plastic framework at finite strains. The model is based on the postulate of covariance and does not rely on a multiplicative decomposition of the deformation gradient. Furthermore, a plastic-deformation-induced evolution of orthotropy is considered, similar to the notion of plastic spin. We propose that the orthotropic strain energy function and the orthotropic yield criterion are guided by identical structural tensors that evolve with plasticity. The modelled material behaviour is significant for natural fibres such as flax, hemp, or pulp fibres. Our formulation has three findings. Firstly, the covariant formulation of plasticity provides rate equations for the plastic variables and the structural tensors suitable for reproducing stress–strain diagrams of natural fibres. Secondly, the introduction of plastic-deformation-induced evolution of orthotropy in the proposed covariant setting results in a non-associative plasticity algorithm. Thirdly, the covariant setting allows the incorporation of suitable constitutive equations for the structural tensors to evolve orthotropy. The latter successfully models the stiffness increase in stress–strain diagrams of cyclic tensile tests of natural fibres.我们介绍了在有限应变下超弹塑性框架中正交各向异性弹性和正交各向异性塑性材料行为的速率无关模型。该模型基于协方差假设,不依赖于变形梯度的乘法分解。此外,考虑了塑性变形诱导的正交异性演化,类似于塑性自旋的概念。我们提出正交各向异性应变能函数和正交各向异性屈服准则由相同的随塑性演化的结构张量指导。模拟材料的行为是显著的天然纤维,如亚麻,大 麻,或纸浆纤维。我们的公式有三个发现。首先,塑性协变公式提供了适于再现天然纤维应力-应变图的塑性变量和结构张量的速率方程。其次,在所提出的协变设置中引入塑性变形诱导的正交异性进化导致非关联塑性算法。第三,协变设置允许结合合适的本构方程的结构张量发展正交异性。后者成功地模拟了天然纤维循环拉伸试验的应力-应变图中的刚度增加。Mechanics of MaterialsA Statistical High-order Reduced Model for Nonlinear Random Heterogeneous Materials with Three-scale Micro-ConfigurationsZhiqiang Yang, Shanqiao Huang, Yi Sundoi:10.1016/j.mechmat.2024.105149具有三尺度微观结构的非线性随机非均质材料的统计高阶简化模型An effective statistical higher-order three-scale reduced homogenization (SHTRH) method is established to analyze the nonlinear random heterogeneous materials with multiple micro-configurations. Firstly, the various unit cell functions based on the microscale and mescoscale regions are given, and two expected homogenization coefficients are computed through Kolmogorov’s strong laws of large number. Further, the nonlinear homogenized equations are formulated, and the corresponding reduced-order multiscale systems for displacement and stress solutions are derived by using the high-order unit cell solutions and homogenized solutions. The key features of the new statistical multiscale methods are (i) the novel reduced models established to solve the inelastic problems of random composites at a fraction of cost, (ii) the high-order homogenized solutions which do not need high-order continuity for the macro solutions of the random problems and (iii) the statistical high-order multiscale algorithms developed for analyzing the nonlinear random composites with three-scale structures. Finally, the effectiveness and correctness of the algorithm are confirmed according to several hyperelastic, plasticity and damage periodic/random composites with multiple-scale configurations. The computation shows that the proposed SHTRH methods are useful for analyzing the macroscopic nonlinear performance, and can efficiently catch the microscopic and mesoscopic information for the random heterogeneous composites.建立了一种有效的统计高阶三尺度简化均质化(SHTRH)方法来分析具有多种微观构型的非线性随机非均质材料。首先,给出了基于微尺度和中尺度区域的各种单体胞函数,并利用Kolmogorov强大数定律计算了两个期望的均匀化系数。在此基础上,建立了非线性均质化方程,并利用高阶单元胞解和均质化解导出了相应的降阶多尺度位移和应力解。新统计多尺度方法的主要特点是:(1)建立了新的简化模型,以较低的成本求解随机复合材料的非弹性问题;(2)随机问题宏观解的高阶均匀化解不需要高阶连续性;(3)开发了用于分析具有三尺度结构的非线性随机复合材料的统计高阶多尺度算法。最后,以多尺度结构的超弹性、塑性和损伤周期/随机复合材料为例,验证了算法的有效性和正确性。计算结果表明,所提出的SHTRH方法可用于分析随机非均质复合材料的宏观非线性性能,并能有效地捕获其微观和细观信息。Modeling plasticity-mediated void growth at the single crystal scale: A physics-informed machine learning approachKarl Garbrecht, Andrea Rovinelli, Jacob Hochhalter, Paul Christodoulou, Ricardo A. Lebensohn, Laurent Capolungodoi:10.1016/j.mechmat.2024.105151在单晶尺度上模拟塑性介导的空洞生长:一种物理信息的机器学习方法Modeling the evolution of voids during plastic flow as well as their effects on plastic dissipation is critical for both component manufacturing and lifetime estimation purposes. To this end, we propose a rate-dependent constitutive model to homogenize the effects of semi-randomly distributed voids on single crystal plasticity whilst capturing void interaction and plastic anisotropy. The present work focuses on the case of face centered cubic crystals to introduce an anisotropic gauge function applicable within the crystal plasticity formalism. The approach combines analytical methods to describe the micromechanics of the system in combination with symbolic regression to capture analytically intractable mechanisms from data. The hybrid framework uses a physics-informed genetic programming-based symbolic regression algorithm to solve a multiform optimization problem simultaneously producing a new gauge function and a new strain rate equation. This is also a multi-objective optimization problem with many competing objectives. A new search and selection step is introduced to the genetic algorithm that promotes convergence toward a global solution that better satisfies all the objectives. Overall, the symbolic equations produced leverage data-driven methods to achieve greater accuracy than comparable alternatives on an analytically intractable problem while maintaining model transparency.模拟塑性流动过程中空洞的演化及其对塑性耗散的影响对于部件制造和寿命估计都是至关重要的。为此,我们提出了一个速率相关的本构模型,以均匀化半随机分布的空洞对单晶塑性的影响,同时捕捉空洞相互作用和塑性各向异性。本文以面心立方晶体为例,介绍了一种适用于晶体塑性形式的各向异性规范函数。该方法结合了分析方法来描述系统的微观力学,并结合符号回归从数据中捕获分析难以处理的机制。该混合框架采用基于物理信息遗传规划的符号回归算法来解决多形式优化问题,同时产生新的规范函数和新的应变率方程。这也是一个有许多竞争目标的多目标优化问题。在遗传算法中引入了一个新的搜索和选择步骤,以促进收敛到一个更好地满足所有目标的全局解。总的来说,产生的符号方程利用数据驱动的方法,在保持模型透明度的同时,在分析棘手问题上获得比可比替代方案更高的准确性。Thin-Walled StructuresExperimental and theoretical studies on 3D printed short and continuous carbon fiber hybrid reinforced compositesXiangren Kong, Guangyong Sun, Quantian Luo, Veniamin Brykin, Jin Qiandoi:10.1016/j.tws.2024.112406 3D打印短连续碳纤维混杂增强复合材料的实验与理论研究3D-printed carbon fiber composites hold significant potential in aerospace applications because of their lightweight, high strength and complex structure fabrication capabilities. However, additive manufacturing characteristics such as high porosity, anisotropy and continuous fiber content significantly affect the mechanical properties of printed parts. The aim of this study is to investigate the influence of hybrid printing of short and continuous carbon fibers on the mechanical properties and failure mechanisms of composites and to develop a model to predict elastic properties considering porosity. First, mechanical testing and characterization of short and continuous fiber reinforced polyamide (nylon) print filaments are performed. The results indicate that the elastic modulus and ultimate strength of continuous carbon fiber filaments reach 60 GPa and 1500 MPa, respectively, while the strength and elastic modulus of short carbon fiber filaments reach 60 MPa and 1 GPa, respectively. Then tensile specimens with different continuous fiber orientations and different continuous fiber placement sequences are printed and tested using a multi-material 3D printing technique. The specimens are characterized before and after testing using scanning electron microscopy and microscopy to assess the porosity and failure mechanisms of specimens with different configurations. The results show that the mechanical properties of the printed parts are much lower than those of the print filaments, which proves the serious negative impact of the material extrusion process on the mechanical properties of the printed structural parts. Finally, an analytical method for predicting the elastic behavior of printed composites is developed by introducing the porosity factor in the volume-averaged stiffness model. For continuous and short fiber filled composites with different fiber contents and printing orientations, the predicted results are in agreement with the experiments, and the prediction error is greatly reduced from 30% to less than 5%.3d打印碳纤维复合材料由于其轻量化、高强度和复杂结构的制造能力,在航空航天应用中具有巨大的潜力。然而,增材制造的高孔隙率、各向异性和连续纤维含量等特性会显著影响打印件的力学性能。本研究的目的是研究短碳纤维和连续碳纤维混合打印对复合材料力学性能和破坏机制的影响,并建立考虑孔隙率的弹性性能预测模型。首先,对短纤维和连续纤维增强聚酰胺(尼龙)打印长丝进行了力学测试和表征。结果表明:连续碳纤维长丝的弹性模量和极限强度分别达到60 GPa和1500 MPa,短碳纤维长丝的强度和弹性模量分别达到60 MPa和1 GPa。然后采用多材料3D打印技术对不同连续纤维取向和不同连续纤维放置顺序的拉伸试样进行打印和测试。利用扫描电镜和显微镜对试验前后的试样进行表征,评估不同构型试样的孔隙率和破坏机制。结果表明,打印件的力学性能远低于打印长丝的力学性能,证明了材料挤压工艺对打印结构件力学性能的严重负面影响。最后,在体积平均刚度模型中引入孔隙率因子,提出了一种预测打印复合材料弹性性能的解析方法。对于不同纤维含量和打印方向的连续和短纤维填充复合材料,预测结果与实验结果吻合较好,预测误差从30%大大降低到5%以下。来源:复合材料力学仿真Composites FEM

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