【新文速递】2024年1月27日固体力学SCI期刊最新文章
今日更新：Journal of the Mechanics and Physics of Solids 2 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 1 篇
Journal of the Mechanics and Physics of Solids
Combined influence of shallowness and geometric imperfection on the buckling of clamped spherical shells
Kanghyun Ki, Jeongrak Lee, Anna Lee
doi:10.1016/j.jmps.2024.105554
浅度和几何缺陷对夹紧球壳屈曲的综合影响
We investigate the combined influence of shallowness and geometric imperfection on the pressure-induced buckling behavior of clamped spherical shells. The buckling phenomenon in spherical shells has gained significant interest in diverse fields, such as soft robotics and biomechanics, due to its distinct and drastic shape morphing characteristics. However, a notable discrepancy between analytic solutions and experimental results persists, necessitating further research to comprehend the buckling behavior of spherical shells with varying shallowness and geometric imperfection. To address this gap, we experimentally investigate the buckling of clamped spherical shells under uniform pressure while controlling the shell shallowness over a wide range. The experimental results validate finite element simulations, enabling analysis of the variation in buckling pressure and behaviors by manipulating the shell shallowness and geometric imperfection. Our analysis reveals decaying oscillatory variations in the buckling strength versus the shallowness curves, eventually converging to stable buckling strength for sufficiently deep shells. Moreover, these curves exhibit changes in level and shape with varying geometric imperfection. We also observe non-axisymmetric buckling modes in shells with small geometric imperfection and specific shallowness ranges. Through parametric studies, we identify the geometric conditions influencing the buckling behavior, particularly the non-snap-through criteria and non-axisymmetric buckling modes. This comprehensive investigation sheds light on the interplay between shallowness and geometric imperfection affecting the buckling behavior of clamped spherical shells. The findings contribute to a deeper understanding of shell buckling phenomena and have implications for various shell design applications.
我们研究了浅度和几何缺陷对夹紧球壳的压力诱导屈曲行为的综合影响。球壳的屈曲现象由于其独特而剧烈的形状变形特征，在软机器人和生物力学等多个领域引起了人们的极大兴趣。然而，解析解与实验结果之间仍然存在显著差异，需要进一步研究以理解不同浅度和几何缺陷的球壳的屈曲行为。为了解决这一差距，我们实验研究了在均匀压力下夹紧球壳的屈曲，同时在很大范围内控制壳的浅度。实验结果验证了有限元模拟，可以通过操纵壳体浅度和几何缺陷来分析屈曲压力和行为的变化。我们的分析表明，在较浅的曲线上，屈曲强度的振荡变化是衰减的，对于足够深的壳，最终收敛到稳定的屈曲强度。此外，这些曲线在不同的几何缺陷下表现出水平和形状的变化。我们还观察到具有较小几何缺陷和特定浅度范围的壳的非轴对称屈曲模式。通过参数化研究，我们确定了影响屈曲行为的几何条件，特别是非卡断准则和非轴对称屈曲模式。这项全面的研究揭示了浅度和几何缺陷之间的相互作用，影响夹紧球壳的屈曲行为。这些发现有助于更深入地理解壳体屈曲现象，并对各种壳体设计应用具有指导意义。
A machine learning perspective on the inverse indentation problem: uniqueness, surrogate modeling, and learning elasto-plastic properties from pile-up
Quan Jiao, Yongchao Chen, Jong-hyoung Kim, Chang-Fu Han, Chia-Hua Chang, Joost J. Vlassak
doi:10.1016/j.jmps.2024.105557
反缩进问题的机器学习视角:唯一性、代理模型和从堆积中学习弹塑性特性
The inverse analysis of indentation curves, aimed at extracting the stress-strain curve of a material, has been under intense development for decades, with progress relying mainly on the use of analytical expressions derived from small data sets. Here, we take a fresh, data-driven perspective to this classic problem, leveraging machine learning techniques to advance indentation technology. Using a neural network (NN), we efficiently assess uniqueness and identify materials that have indistinguishable indentation responses without the need for complex, domain knowledge-based algorithms. We then demonstrate that inclusion of the residual imprint information resolves the non-uniqueness problem. We show that the elasto-plastic properties of a material can be learned directly from indentation pile-up. Notably, an accurate stress-strain curve can be derived using solely the applied indentation load and pile-up information, thereby eliminating the need for depth-sensing. We also present a systematic analysis of the machine learning model, covering important aspects such as prediction performance, sensitivity, feature selection, and permutation importance, providing insight for model development and evaluation. This study introduces and provides the groundwork of a machine-learning-based profilometry-informed indentation inversion (PI3) technique. It showcases the potential of machine learning as a transformative alternative when analytical solutions are difficult or impossible to obtain.
以提取材料应力-应变曲线为目的的压痕曲线逆分析已经得到了几十年的大力发展，其进展主要依赖于使用从小数据集导出的解析表达式。在这里，我们采取了一个新的，数据驱动的角度来解决这个经典问题，利用机器学习技术来推进缩进技术。使用神经网络(NN)，我们有效地评估唯一性并识别具有不可区分的压痕响应的材料，而无需复杂的基于领域知识的算法。然后，我们证明了残余印记信息的包含解决了非唯一性问题。我们证明了材料的弹塑性特性可以直接从压痕堆积中了解到。值得注意的是，仅使用施加的压痕载荷和堆积信息就可以推导出精确的应力-应变曲线，从而消除了深度传感的需要。我们还对机器学习模型进行了系统的分析，涵盖了预测性能、灵敏度、特征选择和排列重要性等重要方面，为模型开发和评估提供了见解。本研究介绍并提供了基于机器学习的轮廓信息缩进反演(PI3)技术的基础。它展示了机器学习作为一种变革性替代方案的潜力，当分析解决方案很难或不可能获得时。
Mechanics of Materials
On the flat punch hole expansion test of sheet metals: Mechanics of deformation and evaluation of anisotropic plasticity models
A. Abedini, A. Narayanan, C. Butcher
doi:10.1016/j.mechmat.2024.104931
板料平冲孔膨胀试验:变形力学及各向异性塑性模型的评价
The conventional approach to calibrating anisotropic yield functions relies upon uniaxial and biaxial tension data. Consequently, the stress state in which plane strain conditions arise is allowed to occur anywhere between uniaxial and equal-biaxial states despite growing experimental evidence suggesting that it is close to the theoretical stress state predicted by pressure-independent plasticity for steel and aluminum alloys. The objective of the study was to investigate the role of the plane strain stress state on yield surface calibration and its influence upon the mechanics of the flat punch hole expansion test. First, a parametric study was performed to determine how the plane strain stress state affects the predicted strain field in flat punch hole expansion simulations of an AA6022-T4 sheet. It is shown that the flat punch hole expansion deformation can be described as being under stress-controlled boundary conditions. The predicted location behind the hole edge where zero minor strain occurs was observed to be directly related to the yield function calibration and its accuracy evaluated from optical strain measurements. It was shown that the thinning strain distributions away from the edge could be well predicted by coupling the major strain gradient near the hole edge (geometry effect) with the normal vectors of the yield function from uniaxial-to-plane strain tension (yield function effect). The resulting best practices for plasticity characterization were then applied to a 3rd Gen 1180 steel. The global and local responses of the 3rd Gen 1180 flat punch hole expansion tests were accurately predicted by simulations using calibrations of the Yld2000 and Yld2004 anisotropic yield functions that enforced the plane strain constraint.
校准各向异性屈服函数的传统方法依赖于单轴和双轴张力数据。因此，尽管越来越多的实验证据表明，它接近由压力无关塑性预测的钢和铝合金的理论应力状态，但允许出现平面应变条件的应力状态发生在单轴和等双轴状态之间的任何地方。研究了平面应变应力状态在屈服面标定中的作用及其对平冲孔膨胀试验力学性能的影响。首先，进行了参数化研究，以确定平面应变应力状态对AA6022-T4板材平冲孔扩展模拟中预测应变场的影响。结果表明，在应力控制的边界条件下，扁冲孔的膨胀变形可以被描述为。观察到，在孔边缘后发生零小应变的预测位置与屈服函数校准及其通过光学应变测量评估的精度直接相关。结果表明，将孔边缘附近的主应变梯度(几何效应)与从单轴到平面的应变张力屈服函数法向量(屈服函数效应)耦合，可以很好地预测孔边缘以外的应变变薄分布。然后将塑性表征的最佳实践应用于第三代1180钢。通过对施加平面应变约束的Yld2000和Yld2004各向异性屈服函数的校正，模拟准确预测了第3代1180平冲孔扩展试验的整体和局部响应。
International Journal of Plasticity
Characterization and unified modelling of creep and viscoplasticity deformation of titanium alloy at elevated temperature
Yong Li, Haosheng Chen, Lihua Du, Feng Yang, Ying Zhang, Dongsheng Li
doi:10.1016/j.ijplas.2024.103892
钛合金高温蠕变与粘塑性变形表征及统一建模
A unified model to characterize the mechanism transitions in a wide range of strain rates at elevated temperatures of titanium alloys has been developed and validated in this study. Models of microstructure-based backstress and strain rate dependent stress sensitivity covering both creep and viscoplasticity domains have been proposed, so as to predict different deformation behaviors concurrently for hot forming. Systematical experiments, including hot tensile, creep, stress-relaxation, and corresponding loading-unloading tests have been designed and performed, to get the different deformation behaviors, as well as the evolution of backstresses of titanium alloys at elevated temperatures. Microstructural observations, such as electron backscatter diffraction (EBSD), have also been performed to assist the mechanisms characterization. Based on the microstructural and macro properties results, the developed unified model has been calibrated and further implemented for typical cases of hot stamping - stress-relaxation forming (HS-SRF). The developed model achieved an excellent accuracy for all the tensile, creep, and stress-relaxation behaviors concurrently, with an error of only about 4.9%, and a comparative 71.8% ∼ 90.8% reduction in springback prediction error has been reported for hot forming of typical thin-walled titanium alloy components when compared with the conventional modelling strategy where a single deformation mechanism is considered. The potential of the proposed model for process design and optimizations has also been discussed.
本研究建立了一个统一的模型来表征钛合金在高温下大范围应变速率下的机制转变。基于微观组织的背应力和应变率相关的应力敏感性模型涵盖了蠕变和粘塑性两个领域，从而可以同时预测热成形的不同变形行为。设计并进行了热拉伸、蠕变、应力松弛和相应的加载-卸载试验，得到了钛合金在高温下的不同变形行为和背应力的演变规律。显微结构观察，如电子背散射衍射(EBSD)，也被用于协助机制表征。基于微观组织和宏观性能的结果，对所建立的统一模型进行了标定，并对热冲压-应力松弛成形(HS-SRF)的典型案例进行了进一步的实施。与考虑单一变形机制的传统建模策略相比，所开发的模型对所有拉伸、蠕变和应力松弛行为同时具有优异的精度，误差仅为4.9%，并且在典型薄壁钛合金部件的热成形中回弹预测误差降低71.8% ~ 90.8%。本文还讨论了所提出的模型在工艺设计和优化方面的潜力。
Thin-Walled Structures
Research on Mechanical Properties of Duplex Stainless Steel S22053 at Elevated Temperature and after Fire
Tiancheng Chen, Shenggang Fan, Qingfeng Xu, Kuiyuan Xu, Jinpeng Luo, Yuxian Tang
doi:10.1016/j.tws.2024.111620
S22053双相不锈钢高温及火后力学性能研究
Stainless steel has advantages such as corrosion resistance, durability and aesthetic appearance, with extensive application prospects in the field of construction engineering. In order to investigate the mechanical properties of duplex stainless steel S22053 at elevated temperature and after fire, 58 standard coupons were fabricated, with 4 coupons for tensile tests at ambient temperature, 18 coupons for steady-state tests at elevated temperatures, and 36 coupons for tensile tests after fire. The temperatures were set at 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C and 900 °C, in total of 9 temperature levels. Two cooling methods, water cooling and air cooling, were employed for the postfire coupons. Based on the test results, the expressions of stress-strain relations for duplex stainless steel S22053 under two fire conditions were proposed, and comparisons were made with existing models. The reduction formulas for 6 major mechanical parameters (E0, σ0.05, σ0.2, σ1.0, σ2.0 and σu) of duplex stainless steel S22053 under two fire conditions were obtained through data fitting. Reliability analysis was performed on the mechanical property parameters, and corresponding standard values were proposed.
不锈钢具有耐腐蚀、耐用、美观等优点，在建筑工程领域具有广泛的应用前景。为了研究双相不锈钢S22053在高温和火灾后的力学性能，制作了58个标准试样，其中4个试样用于常温拉伸试验，18个试样用于高温稳态拉伸试验，36个试样用于火灾后拉伸试验。温度设置为100°C、200°C、300°C、400°C、500°C、600°C、700°C、800°C和900°C，共9个温度级别。火后汽票采用水冷却和风冷两种冷却方式。根据试验结果，提出了两种火灾条件下双相不锈钢S22053的应力应变关系式，并与已有模型进行了比较。通过数据拟合得到了两种着火条件下双相不锈钢 S22053 的 6 个主要力学参数（E0、σ0.05、σ0.2、σ1.0、σ2.0 和 σu）。对力学性能参数进行了可靠性分析，并提出了相应的标准值。
