今日更新:International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇
A Mesoscale Crystal Plasticity Model to Predict Room-Temperature Deformation and Martensitic Transformation of High-Strength Quenching and Partitioning (Q&P) Steels and Validation with Synchrotron X-ray Diffraction
Jiahao Cheng, Brian K Lin, Narayan S. Pottore, Sriram Sadagopan, Hong Zhu, Xiaohua Hu
doi:10.1016/j.ijplas.2023.103833
预测高强度淬火与配分(Q&P)钢室温变形和马氏体转变的中尺度晶体塑性模型以及同步辐射 X 射线衍射验证
Renowned for the superior mechanical properties and adeptness at cold-forming, Quenching and Partitioning (QP) steels have gained prominence as a promising candidate material in fabricating safety-critical components in various industries. The pertinent research on QP steels focus on the martensitic transformation of the Retained Austenite (RA) phase during cold-forming, a crucial mechanism that substantially influences the overall strength and ductility of QP steels. The austenite stability and transformation rate heavily rely on the local strain path and the initial microstructure, which is challenging for analytical prediction. In this paper, a mesoscale model is developed to capture the deformation and transformation kinetics of QP steels inside the microstructure. The model integrates the detailed explicit microstructure, acquired from characterization experiments, into a high-resolution finite element (FE) mesh. It distinctly model the deformation and interaction between the various phases and the effect on the transformation of RA. The model is validated with high energy X-ray diffraction (HEXRD) data, and shows excellent capability in predicting the asymmetric stress-strain behavior under uniaxial tension and compression, as well as the martensitic transformation rate. The model is used to investigate the strain and load partitioning effect of surrounding matrix to the transformation of RA, offering insights into the complex behavior of QP980 and facilitates further material development.
淬火与隔热(QP)钢以其卓越的机械性能和冷成形能力而闻名,已成为各行业制造安全关键部件的理想候选材料。对 QP 钢的相关研究主要集中在冷成形过程中残余奥氏体(RA)相的马氏体转变上,这一关键机制对 QP 钢的整体强度和延展性产生了重大影响。奥氏体稳定性和转化率在很大程度上取决于局部应变路径和初始微观结构,这对分析预测具有挑战性。本文建立了一个中尺度模型,以捕捉 QP 钢在微观结构内部的变形和转变动力学。该模型将从表征实验中获得的详细明确的微观结构集成到高分辨率有限元(FE)网格中。该模型清晰地模拟了各种相之间的变形和相互作用,以及对 RA 转变的影响。该模型通过高能 X 射线衍射(HEXRD)数据进行了验证,在预测单轴拉伸和压缩下的非对称应力-应变行为以及马氏体转变率方面显示出卓越的能力。该模型用于研究周围基体对 RA 转变的应变和载荷分配效应,有助于深入了解 QP980 的复杂行为,并促进材料的进一步开发。
Flexural–torsional buckling of steel circular arches with I-section under central concentrated load in elevated-temperature environment
Ya-Chao Hu, Feng Xi, Feng Liu, Yu-Chao Yang, Ying-Hua Tan
doi:10.1016/j.tws.2023.111460
高温环境下中心集中荷载作用下 I 型截面钢圆弧拱的挠扭屈曲
This article reports the fire resistance experiments conducted on I-section circular steel arches, as well as the observed out-of-plane flexural–torsional buckling (FTB) behavior and in-depth finite element numerical simulation results. The test was carried out using a large fire test furnace to provide a real fire environment with a nonuniform temperature field. A specially designed loading device allowed for unconstrained out-of-plane deformation of the specimens inside the furnace, thereby achieving effective load conditions and noncoupled response of the components. Numerical analyses were performed using a combination of the general codes Fluent and Abaqus, with the former used for heat transfer analyses, and a structural FE model including the loading device and complex geometric imperfections was established based on the measured data. Thus, accurate simulation of the out-of-plane behavior of the steel arches at elevated temperature was achieved. On this basis, an in-depth parametric study was carried out to investigate the effects of temperature field variations, load ratio (LR), and geometric imperfection. The analysis results show that FTB occurs at nonuniform temperatures for the arches under concentrated load, and the difference in temperature distribution in fire has a minimal effect on the FTB behavior. LR is negatively correlated with critical temperature; the smaller the LR, the more significant the weakening of critical loads by fire. The effect of initial geometrical imperfections on FTB at elevated temperatures is similar to that at ambient temperatures, and the effect on the critical temperature of FTB can almost be ignored when the imperfection amplitude is less than S/400.
本文报告了对 I 型截面圆形钢拱架进行的耐火试验,以及观察到的平面外弯曲扭转屈曲(FTB)行为和深入的有限元数值模拟结果。试验使用大型火灾试验炉进行,以提供温度场不均匀的真实火灾环境。专门设计的加载装置允许试样在炉内无约束地发生平面外变形,从而实现有效的加载条件和组件的非耦合响应。数值分析结合使用了通用代码 Fluent 和 Abaqus,前者用于传热分析,后者则根据测量数据建立了包括加载装置和复杂几何缺陷在内的结构 FE 模型。因此,实现了对钢拱架在高温下平面外行为的精确模拟。在此基础上,对温度场变化、载荷比 (LR) 和几何缺陷的影响进行了深入的参数研究。分析结果表明,在集中荷载作用下,拱形结构在非均匀温度下发生 FTB,而火灾中的温度分布差异对 FTB 行为的影响微乎其微。LR 与临界温度呈负相关;LR 越小,火灾对临界荷载的削弱越明显。初始几何缺陷在高温下对 FTB 的影响与常温下类似,当缺陷振幅小于 S/400 时,对 FTB 临界温度的影响几乎可以忽略。
The fluid-structure interaction response of composite auxetic re-entrant honeycomb structures to underwater impact
Jiayi Liu, Xiaolong He, Zhikang Liu, Xiaoming Cao, Sheng Yu, Wei Huang
doi:10.1016/j.tws.2023.111465
复合辅助再入式蜂窝结构对水下冲击的流固耦合响应
In this paper, the effects of the gradient form, peak pressure and decaying time on the fluid-structure interaction of composite auxetic re-entrant honeycomb structures was experimentally and numerically investigated. The specimens for this experiment were manufactured by hot-press molding method. The acrylic transparent tube was utilized to accommodate water medium, pistons and specimen during experiment. The exponential decaying shock wave was simulated by accelerating the fly plate to impact the piston based on the one-stage light gas gun system. The incident velocity of the fly plate and process of the fluid-structure interaction response were monitored by high frame rate camera. In addition, the velocity of the shock wave in water was measured by transducers installed at different measuring points. The voltage signal of the dynamic overpressure collected by transducers was amplified by the charge amplifier and recorded by the oscilloscope. On the other hand, finite element software Abaqus/Explicit was applied to simulate the cavitation process of water domain and dynamic response of specimens. The experimental results and numerical results were in good agreement. The results indicated that the increase of the thickness of the fly plate had a certain effect on the propagation velocity of the shock wave, and the increase of the peak pressure would make the cavitation generation position close to the fluid-structure interface and make the cavitation duration longer. And the average structure which has a minimum transformation of 8.12 mm shows better underwater impact resistance than the gradient structure.
本文通过实验和数值方法研究了梯度形式、峰值压力和衰减时间对复合辅助再入式蜂窝结构流固耦合作用的影响。实验中的试样采用热压成型法制造。在实验过程中,利用丙烯酸透明管来容纳水介质、活塞和试样。在单级光气 枪系统的基础上,通过加速飞板冲击活塞来模拟指数衰减冲击波。飞板的入射速度和流体与结构相互作用的响应过程由高帧率摄像机进行监测。此外,还通过安装在不同测量点的传感器测量了水中冲击波的速度。传感器采集的动态超压电压信号经电荷放大器放大后由示波器记录。另一方面,应用有限元软件 Abaqus/Explicit 模拟了水域的空化过程和试样的动态响应。实验结果和数值结果非常吻合。结果表明,飞流板厚度的增加对冲击波的传播速度有一定影响,峰值压力的增加会使空化产生位置靠近流体-结构界面,空化持续时间延长。与梯度结构相比,最小变形量为 8.12 毫米的平均结构具有更好的水下抗冲击性能。