今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Thin-Walled Structures 3 篇
A generalized strain model for nonlinear residually stressed magneto-electrically coupled viscoelastic solids
M.H.B.M. Shariff, R. Bustamante, J. Merodio
doi:10.1016/j.ijsolstr.2024.112659
非线性残余应力磁电耦合粘弹性固体的广义应变模型
In this communication a generalized strain approach is proposed, in order to obtain constitutive equations for nonlinear residually stressed magneto-electric coupled viscoelastic solids with short term memory. This approach is a change with respect to the work that has been done in the last decades regarding mechanics of nonlinear solids. The generalized strain model uses spectral invariants, where they have a clear physical meaning and hence are attractive for use in experiments. A specific form for a constitutive equation containing single-variable functions is presented, which are easy to deal with, if compared to multivariable functions. The effects of viscosity, residual stress and magneto-electric fields are studied via the results of boundary value problems, and some of these results are compared with experimental data.
本文提出了一种广义应变方法,以获得具有短期记忆的非线性残余应力磁电耦合粘弹性固体的构成方程。这种方法改变了过去几十年中有关非线性固体力学的研究。广义应变模型使用频谱不变量,这些不变量具有明确的物理意义,因此在实验中很有吸引力。本文介绍了包含单变量函数的构成方程的具体形式,与多变量函数相比,单变量函数易于处理。通过边界值问题的结果研究了粘度、残余应力和磁电场的影响,并将其中一些结果与实验数据进行了比较。
On the theory of mechanically induced chemiluminescence in multiple network elastomers
Peng Sun, Shaoxing Qu, Rui Xiao
doi:10.1016/j.jmps.2024.105543
论多重网络弹性体的机械诱导化学发光理论
Mechanophores, force-sensitive molecules, can be covalently linked into polymer networks to reveal the damage properties of polymeric materials under deformation. Recent works have introduced bis-adamantyl dioxetane (Ad) into multiple network elastomers. These mechanoluminescent cross-linking molecules can emit luminescence as they break. The experimental results can directly visualize the damage behaviors of multiple network elastomers and reveal the damage mechanism of these materials during deformation. In this work, we develop a constitutive model to describe the complex mechanical behaviors of multiple network elastomers based on observations from mechano-chemiluminescent experiments. The free energy density consists of the contributions from the filler network, the matrix network, and the entangled network. A new type of single-chain model is developed for the filler network, while the classic eight-chain mapping is adopted for the micro-macro transition. The chains in the filler network are progressively damaged under deformation to explain the stress-softening behaviors observed in the small and median strain regions of multiple network elastomers. The entangled network is rooted in individual fragments of the damaged filler network, which can be further damaged in the large deformation regime. The model can comprehensively capture the complex mechanical responses of multiple network elastomers with different values of the prestretching ratio of the filler network, including linear response, necking instability, and re-hardening phenomena in quadruple networks. By assuming that the luminescence intensity of the materials is proportional to the total percentage of damage from both filler and entangled networks, we quantify the relationship between damage and the luminescence intensity from mechanophores, which is further validated in quantifying luminescence intensity against different sets of experimental data on the uniaxial tension of multiple network elastomers. The model is further implemented for finite element analysis, demonstrating the ability to visualize and characterize the damage behaviors around a crack.
力学分子是对力敏感的分子,可通过共价键连接到聚合物网络中,从而揭示聚合物材料在变形过程中的破坏特性。最近的研究将双金刚烷基二氧杂环丁烷(Ad)引入到多种网络弹性体中。这些机械发光交联分子可在断裂时发出荧光。实验结果可以直接观察到多重网络弹性体的损伤行为,并揭示这些材料在变形过程中的损伤机理。在这项工作中,我们根据机械化学发光实验的观察结果,建立了一个构成模型来描述多重网络弹性体的复杂机械行为。自由能密度由填料网络、基体网络和缠结网络的贡献组成。针对填料网络开发了一种新型单链模型,而针对微观-宏观过渡则采用了经典的八链映射。填充网络中的链在变形过程中逐渐损坏,从而解释了在多网络弹性体的小应变区和中值应变区观察到的应力软化行为。缠结网络植根于受损填充网络的单个片段,在大变形机制中会进一步受损。该模型能全面捕捉不同填充网络预拉伸比值的多重网络弹性体的复杂机械响应,包括线性响应、颈缩不稳定性和四重网络中的再硬化现象。通过假定材料的发光强度与填料和纠缠网络的总损伤百分比成正比,我们量化了损伤与来自机械分子的发光强度之间的关系,并根据多网络弹性体单轴拉伸的不同实验数据集进一步验证了发光强度的量化。该模型进一步用于有限元分析,展示了可视化和描述裂纹周围损伤行为的能力。
Axial compressive behavior of high-strength steel-UHPC-clad steel composite walls
Ying Wang, Xiang Li, Tianyu Liao, Zhichao Lai, Chenxi Fang, Junbo Zuo
doi:10.1016/j.tws.2024.111588
高强度钢-UHPC 包钢复合墙体的轴向抗压行为
This paper proposed a novel high-strength steel-UHPC-clad steel composite wall (HS-UHPC-CS composite wall) and investigated its axial compressive behavior through experimental and numerical methods. A total of 18 axial compressive tests and finite element (FE) analyses, including parametric studies of 120 cases, were conducted. It was shown that the stud spacing-to-plate thickness ratio and the normalized slenderness ratio notably affected the strength and local buckling, while their influence on the initial stiffness was minor. The strength and initial stiffness were improved, while the ductility was compromised by the presence of ultra-high-performance concrete (UHPC). Steel fiber was critical to the HS-UHPC-CS composite wall, while the lack of steel fiber could trigger premature brittle failure. The influence of the strength of concrete was higher compared to steel plate. The critical buckling stress of the steel plate was calculated using Euler's buckling formula for the clad steel plate of the HS-UHPC-CS composite wall. The results were compared with the ordinary composite wall database. In addition, strength from test results, FE results, and the database were compared were compared with strength calculated by design provisions. It was found that the calculated strength was close but not safe. It was recommended that different concrete contribution coefficients should be applied for HS-UHPC-CS composite walls with different normalized slenderness ratios.
本文提出了一种新型高强度钢-UHPC-覆层钢复合墙体(HS-UHPC-CS 复合墙体),并通过实验和数值方法研究了其轴向抗压行为。共进行了 18 次轴向抗压试验和有限元(FE)分析,包括 120 个案例的参数研究。结果表明,螺栓间距与板厚之比和归一化细长比对强度和局部屈曲有显著影响,而对初始刚度的影响较小。超高性能混凝土(UHPC)的存在提高了强度和初始刚度,而延展性则受到了影响。钢纤维对 HS-UHPC-CS 复合墙体至关重要,而缺乏钢纤维则会引发过早的脆性破坏。与钢板相比,混凝土强度的影响更大。采用欧拉屈曲公式计算了 HS-UHPC-CS 复合墙体包覆钢板的临界屈曲应力。结果与普通复合墙体数据库进行了比较。此外,还将测试结果、FE 结果和数据库中的强度与设计规定计算出的强度进行了比较。结果发现,计算出的强度虽然接近,但并不安全。建议对不同归一化细长比的 HS-UHPC-CS 复合墙体采用不同的混凝土贡献系数。
S890 hot-rolled ultra-high strength steel (UHSS) seamless circular hollow section beam–columns: Testing, modelling and design
Yajin Wang, Andi Su, Hua Yang, Jian Zhao, Yuyin Wang
doi:10.1016/j.tws.2024.111583
S890 热轧超高强度钢 (UHSS) 无缝圆形空心截面梁柱:测试、建模和设计
With the recent rapid development of manufacturing techniques and material science, advanced hot-rolling of ultra-high strength steel (UHSS) with material grades up to S890 becomes possible. The structural behaviour of S890 hot-rolled ultra-high strength steel (UHSS) seamless circular hollow section (CHS) beam–columns fabricated through the advanced manufacturing method, was investigated through testing and numerical modelling and reported in this paper. In the physical testing, a total of 12 beam–columns were firstly tested featuring the flexural buckling failure mode, with the material coupon tests and initial global geometric imperfection measurements performed. FE modelling was then conducted, where the FE models were developed and validated against the test observations. The validated FE models were then adopted in the parametric studies in a wider spectrum of member lengths, cross-section dimensions and loading combinations, resulting in the additional 300 FE data to be generated. Finally, the current design provisions, as set out in Eurocode, American specification and Australian standard, are assessed for their applicability to S890 hot-rolled UHSS seamless CHS beam–columns. It was revealed from the assessment results that the design provisions in three design codes can be accurately applied to S890 hot-rolled UHSS seamless CHS beam–columns.
随着近年来制造技术和材料科学的快速发展,材料等级高达 S890 的超高强度钢(UHSS)的先进热轧技术已成为可能。本文通过测试和数值模拟研究了采用先进制造方法制造的 S890 热轧超高强度钢(UHSS)无缝圆形空心截面(CHS)梁柱的结构行为,并对其进行了报告。在物理测试中,首先对 12 根梁柱进行了挠曲屈曲失效模式测试,并进行了材料试样测试和初步的全局几何缺陷测量。然后进行 FE 建模,开发 FE 模型并根据测试观测结果进行验证。经过验证的 FE 模型随后被应用于参数研究,研究范围包括更广泛的构件长度、横截面尺寸和加载组合,从而产生了额外的 300 个 FE 数据。最后,评估了欧洲规范、美国规范和澳大利亚标准中的现行设计规定对 S890 热轧 UHSS 无缝 CHS 梁柱的适用性。评估结果表明,三种设计规范中的设计规定均可准确地应用于 S890 热轧 UHSS 无缝 CHS 梁柱。
Investigation on the mechanical properties and damage mechanisms of plain-woven composites at elevated temperatures through a newly-designed testing system
Hao Lu, Tao Zheng, Li Zhang, Xiaodong Liu, Jindi Zhou, Xiaojian Han, Licheng Guo
doi:10.1016/j.tws.2024.111587
通过新设计的测试系统研究平织复合材料在高温下的力学性能和损伤机理
In this paper, the mechanical properties and damage mechanisms of T800/epoxy plain-woven composites at elevated temperatures are investigated by using a newly-designed testing system, including improved digital image correlation (DIC) equipment, modified fixture and dedicated environmental chamber. The molecular structure, glass transition temperature (Tg) and thermal stability of the composites and epoxy resin are separately characterized. The tensile and compressive experiments of plain-woven composites are conducted at 20°C, 60°C, 100°C and 150°C. The full-field strain distributions of plain-woven composites at elevated temperatures can be accurately measured by the newly-designed testing system. The experimental results indicate that the modulus, failure strengths and damage mechanisms of plain-woven composites are highly temperature dependent. In general, the tensile and compressive moduli decrease slightly with increasing temperature, and the temperature exhibits a more pronounced weakening effect on compressive strength. When the temperature exceeds Tg, the resin attached to fiber yarns is gelatinous. High temperatures severely degrade the interlayer performance of plain-woven composites, resulting in severe delamination accumulation. Particularly, a modified Gibson model is proposed to predict the failure strengths of plain-woven composites at elevated temperatures, which is in high agreement with the experimental results.
本文使用新设计的测试系统,包括改进的数字图像相关(DIC)设备、改良的夹具和专用环境室,研究了 T800/ 环氧平织复合材料在高温下的力学性能和损伤机理。分别对复合材料和环氧树脂的分子结构、玻璃化转变温度(Tg)和热稳定性进行了表征。在 20°C、60°C、100°C 和 150°C 下对平织复合材料进行了拉伸和压缩实验。新设计的测试系统可精确测量平织复合材料在高温下的全场应变分布。实验结果表明,平织复合材料的模量、破坏强度和破坏机制与温度高度相关。一般来说,拉伸模量和压缩模量随温度升高而略有下降,而温度对压缩强度的削弱作用更为明显。当温度超过 Tg 时,附着在纤维纱上的树脂呈胶状。高温会严重降低平织复合材料的层间性能,导致严重的分层累积。特别是提出了一种改进的 Gibson 模型来预测平织复合材料在高温下的破坏强度,该模型与实验结果高度吻合。