
今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 2 篇,International Journal of Plasticity 3 篇
Study of fracture behavior of α-quartz crystals with trigonal symmetry using combined experimental and modelling techniques
Mohammad Safi, Shank S. Kulkarni, Pooyan B. Javadzadeh, Timothy Truster, Hongbing Lu, Khalid A. Alshibli
doi:10.1016/j.ijsolstr.2026.114027
采用实验与模拟相结合的方法研究三角形对称α-石英晶体断裂行为
The fracture of silica sand (α-quartz crystals) is significantly influenced by factors acting at both the macroscopic and microscopic levels. Prior research has established that α-quartz exhibits anisotropic behavior, meaning its mechanical properties vary depending on the loading direction. However, the existing literature lacks conclusive findings on how material orientation influences the fracture behavior of sand. This paper provides a mechanics-based experimental calibration of orientation-dependent fracture energy ( G c ) in single-crystal α-quartz and demonstrates how crystallographic anisotropy alters crack initiation, peak load, and crack-path evolution within a controlled phase-field framework. Systematic 3-point bending tests were conducted on U-notched plates and nanoindentation measurements were performed to verify crystallographic orientation. The resulting force–displacement curves were used to quantify fracture response under different notch geometries. A phase-field formulation incorporating trigonal elastic anisotropy was implemented to simulate crack propagation without prescribing crack paths. Numerical simulations were used to calibrate orientation-specific fracture energy values by minimizing the discrepancy between simulated and experimental peak loads. The calibrated fracture energies provide a quantitative basis for incorporating crystallographic anisotropy into particle-scale fracture models of silica sand. Unlike prior phase-field studies that assume prescribed anisotropic fracture parameters or focus on polycrystalline media, the present work directly links experimentally measured force–displacement responses to orientation-specific fracture energy in α-quartz crystals.
硅砂(α-石英晶体)的断裂受宏观和微观因素的显著影响。先前的研究已经确定α-石英表现出各向异性行为,这意味着它的力学性能随加载方向而变化。然而,现有文献缺乏关于材料取向如何影响砂的断裂行为的结论性发现。本文提供了一种基于力学的α-石英单晶断裂能(G c)的实验校准方法,并证明了晶体各向异性如何在受控相场框架内改变裂纹起裂、峰值载荷和裂纹路径演化。对u型缺口板进行了系统的三点弯曲试验,并进行了纳米压痕测量以验证晶体取向。得到的力-位移曲线用于量化不同缺口几何形状下的断裂响应。采用含三角弹性各向异性的相场公式,在不规定裂纹路径的情况下模拟裂纹扩展。数值模拟通过最小化模拟峰值载荷与实验峰值载荷之间的差异来校准定向断裂能值。校正后的裂缝能为将晶体各向异性纳入硅砂颗粒尺度裂缝模型提供了定量依据。与先前的相场研究假设规定的各向异性裂缝参数或关注多晶介质不同,本研究将实验测量的力-位移响应与α-石英晶体中定向断裂能直接联系起来。
Couplant-free and High-purity Excitation of Unidirectional Shear Waves via a Meta-exciter
Weijian Zhou, Muyang Li, Miao Yang, Yang Liu, He Sun, Zheng Zhong, Bin Wu, Weiqiu Chen
doi:10.1016/j.jmps.2026.106652
利用元激振器激发无耦合器和高纯度的单向剪切波
Traditional shear wave excitation faces a fundamental trade-off: high modal purity requires rigid tangential coupling (bonding or couplant), limiting scanning flexibility and throughput—critical for inline inspection. Portable methods (EMATs, laser ultrasound) suffer from low efficiency and multimodal interference. This work proposes a normal-encoding paradigm that enables high-purity directional shear wave excitation using only normal surface contact, eliminating the need for tangential stress trans mission. The principle exploits standing wave nodes formed by SV-Rayleigh interference in a half-space: at these nodes, tangential displacement vanishes while normal displacement exhibits a prescribed phase distribution. Placing a normally oriented point-source array at these nodes with the designed phase gradient synthesizes a directional SV wavefield without any tangential traction—shifting excitation from tangential-pushing to normal-encoding. This inherently supports rapid, couplant-free scanning. An an alytical relation linking SV angle to array spacing and phase gradient enables inverse design; a plane wave expansion model allows rapid wavefield computation. Finite-element simulations indicate an SV energy proportion exceeding 90%; experiments on a 1 mm aluminum plate (plane stress approximation) further demonstrate beam steering within 1°. This work establishes a rigorous framework for high-efficiency, couplant-free ultrasonic inspection with strong potential for automated inline NDT and elastography.
传统的横波激励面临着一个基本的权衡:高模态纯度需要刚性的切向耦合(键合或耦合剂),限制了扫描的灵活性和吞吐量——这对在线检测至关重要。便携式方法(EMATs、激光超声)存在效率低、多模态干扰等问题。这项工作提出了一种正常编码范式,使高纯度的定向剪切波激发仅使用法向表面接触,消除了切向应力传输的需要。该原理利用半空间中由SV-Rayleigh干涉形成的驻波节点:在这些节点上,切向位移消失,而法向位移呈现规定的相位分布。在这些节点上放置一个具有设计相位梯度的正向定向点源阵列,可以合成一个定向SV波场,而不需要任何从切向推进到正向编码的切向牵引移动激励。这本质上支持快速,无耦合扫描。SV角与阵列间距和相位梯度之间的解析关系使逆向设计成为可能;平面波展开模型允许快速波场计算。有限元模拟表明,SV能量占比超过90%;在1毫米铝板上的实验(平面应力近似)进一步证明了光束在1°内的转向。这项工作为高效、无耦合器的超声波检测建立了严格的框架,具有自动化在线无损检测和弹性成像的强大潜力。
Shear and compaction bands in porous rocks with a micromechanics-inspired non-local elastoplastic model
Jun Wu, Wei Wang, John Rudnicki, Jianfu Shao
doi:10.1016/j.jmps.2026.106648
基于微力学启发的非局部弹塑性模型的多孔岩石剪切和压实带
This study develops a novel approach for modeling shear and compaction bands in porous rock-like materials. A micromechanics-inspired constitutive model is first formulated to describe the fundamental mechanical response of porous rocks by incorporating the evolution of microstructure during plastic deformation. The novel non-local formulation is based on the interaction effect of spatial porosity distribution. Within this approach, the void and crack nucleation drives the shear deformation and localization, while the pore collapse controls the volumetric compaction and localization. The new model is implemented in the standard ABAQUS platform, providing a robust tool for investigating the formation of shear-compaction bands under various loading conditions. The results demonstrate that the proposed model accurately reproduces the transition of macroscopic pressure-sensitive plastic behavior from being dominated by pore and crack nucleation to pore collapse as confining pressure increases, thereby correctly capturing the brittle-ductile transition in the mechanical behavior of porous rocks. The model successfully captures the transition from shear bands to compaction bands under varying confining pressures, along with the associated microstructural evolution. During shear band formation, softening behavior driven by pore and crack nucleation dominates within the band, while the region outside the band undergoes elastic unloading. In the formation of shear-enhanced compaction bands, neither pore and crack nucleation nor pore collapse prevails due to their competitive interaction, resulting in multiple inclined or wavy bands, with continuous plastic development of porosity both inside and outside the bands. In the formation of pure compaction bands, discrete bands perpendicular to the maximum principal stress direction are formed, with hardening behavior induced by pore collapse dominating within the band.
本研究开发了一种模拟多孔类岩石材料中剪切和压实带的新方法。本文首先建立了一个基于细观力学的本构模型来描述多孔岩石在塑性变形过程中微观结构的演化过程。这种新的非局部公式是基于孔隙度空间分布的相互作用。在该方法中,孔隙和裂纹形核驱动剪切变形和局部化,孔隙崩塌控制体积压实和局部化。新模型在标准ABAQUS平台上实现,为研究各种荷载条件下剪切压实带的形成提供了一个强大的工具。结果表明,该模型准确地再现了宏观压敏塑性行为随围压增大由孔隙和裂纹成核主导向孔隙崩塌主导的转变过程,从而正确地捕捉了多孔岩石力学行为中的脆性-韧性转变过程。该模型成功捕获了在不同围压下从剪切带到压实带的转变,以及相关的微观结构演变。剪切带形成过程中,剪切带内以孔隙和裂纹成核驱动的软化行为为主,剪切带外则以弹性卸载为主。在剪切增强压实带的形成过程中,由于孔隙和裂纹的竞争相互作用,孔隙和裂纹既不成核,也不崩溃,形成多条倾斜或波浪状带,带内外孔隙度不断塑性发展。在纯压实带的形成中,垂直于最大主应力方向的离散带形成,带内主要由孔隙崩塌引起的硬化行为。
Critical Role of Highly Malleable Laves Phase on the Structure-Property Correlation in High Entropy Alloys
P.K. Ojha, S. Yoshida, C. Prakash, N. Tsuji, P.P. Bhattacharjee
doi:10.1016/j.ijplas.2026.104712
高延展性叶片相在高熵合金中组织-性能相关性中的关键作用
The microstructure and properties of CoCrFeNi2.1(HfNbTa) x (x = 0.3 and 0.4) of (FCC+Laves) dual-phase HEAs were studied in this work. The homogenized (HfNbTa)0.3 and (HfNbTa)0.4 HEAs showed highly off-stoichiometric cubic C15 Laves phase with volume fractions of ∼15% and 25%, respectively. Regardless of the volume fraction of the Laves phase, the off-stoichiometry, site occupancy preferences of specific elements, and energy factors contributed to the stability of the cubic C15 Laves phase in both HEAs. Nanoindentation results confirmed that the Laves phase in both HEAs was deformable under rolling (i.e. malleable), a finding supported by its elongated morphology and significant strain-partitioning during cold-rolling. The exceptional malleability observed in the off-stoichiometric Laves phase was attributed to its remarkable propensity for nano-twin (< 10 nm thickness) formation on the {111}<11 2 ¯ > system via the synchroshear mechanis m. Annealing produced an ultrafine equiaxed FCC phase with abundant D019 ε phase precipitates, effectively inhibiting grain growth. While the Laves phase fraction in both HEAs remained almost unchanged across annealing temperatures, the ε phase fraction decreased as its size and spacing increased. The cold-rolled (HfNbTa)0.3 HEA annealed at 800°C, having an optimal Laves phase fraction, ultrafine-grained FCC matrix, and finely dispersed nano-precipitates, exhibited a combination of yield and ultimate tensile strengths (YS: 1132±2.5 MPa, UTS: 1323±24 MPa) and total elongation of ∼10%, superior to many HEAs. The qualitative and quantitative ana lyses of the elongation mechanis m and the contributions of individual strengthening mechanis ms demonstrated a critical role of the Laves phase in structure-property correlation on these HEAs.
研究了(FCC+Laves)双相HEAs的CoCrFeNi2.1(HfNbTa) x (x = 0.3和0.4)的微观结构和性能。均质化的(HfNbTa)0.3和(HfNbTa)0.4 HEAs显示出高度非化学计量的立方C15 Laves相,体积分数分别为~ 15%和25%。无论Laves相的体积分数如何,非化学计量学、特定元素的位置占用偏好和能量因素都有助于两种HEAs中立方C15 Laves相的稳定性。纳米压痕结果证实,这两种HEAs中的Laves相在轧制过程中是可变形的(即可锻铸),这一发现得到了其拉长形态和冷轧过程中显著的应变分配的支持。在非化学计量Laves相中观察到的特殊延展性归因于其在{111}< 11.2¯>体系上通过同步剪切机制形成纳米孪晶(厚度< 10 nm)的显著倾向。退火形成具有丰富D019 ε相的超细等轴FCC相,有效地抑制了晶粒的生长。两种HEAs中的Laves相分数在不同退火温度下基本保持不变,而ε相分数则随着其尺寸和间距的增加而减小。经800℃退火的冷轧(HfNbTa)0.3 HEA具有最佳Laves相分数、超细晶FCC基体和分散的纳米析出相,其屈服强度和极限抗拉强度(YS: 1132±2.5 MPa, UTS: 1323±24 MPa)和总伸长率为~ 10%,优于许多HEAs。定性和定量分析表明,Laves相在这些HEAs的结构-性能相关性中起着关键作用。
Nanoscale probing of slip-mediated plastic anisotropy and associated energy dissipation in energetic crystals
Quan Li, Lichen Bai, Xiaochuan Sun, Huajie Song, Yue Liu
doi:10.1016/j.ijplas.2026.104710
含能晶体中滑移介导的塑性各向异性和相关能量耗散的纳米尺度探测
Energetic crystal materials (ECMs) are widely used in civilian and military applications due to their high energy density. Large-scale energy release in ECMs originates from microscopic energy accumulation, which is strongly governed by crystal anisotropy and inherently linked to dislocation activity. However, experimental quantification of dislocation-dominated deformation and the associated energy dissipation in ECMs remains challenging, particularly at the initial and early stages of dislocation slip, where precise nanoscale control of deformation is required. Here, we present a nanoindentation-based framework that leverages nanoscale pop-in events to reveal dislocation-dominated plastic anisotropy in ECMs. This framework enables quantitative determination of the critical resolved shear stress (CRSS) and plastic work associated with dislocation nucleation, multiplication, migration, and pinning-depinning. Demonstrated in representative orthorhombic structure ECM, hexahydro-1,3,5-trinitro-1,3,5-triazine (α-RDX), the CRSS for activation of primary slip systems is determined to be 35.7 ± 0.3 MPa for {011}<01 1 ¯ >, 13.2 ± 0.1 MPa for {010}<100>, and 28.4 ± 0.2 MPa for {110}<1 1 ¯ 0>. Energy statistical an alysis reveals that dislocation multiplication in the {010}<100> slip system most effectively accommodates plastic work. This study establishes a semi-quantitative framework for elucidating nanoscale, dislocation-dominant plastic anisotropy and associated microscopic energy dissipation mechanis ms in ECMs.
含能晶体材料因其高能量密度而广泛应用于民用和军事领域。ecm中的大规模能量释放源于微观能量积累,而微观能量积累受晶体各向异性的强烈控制,并与位错活动有内在联系。然而,在ecm中,位错主导的变形和相关能量耗散的实验量化仍然具有挑战性,特别是在位错滑移的初始和早期阶段,需要精确的纳米级变形控制。在这里,我们提出了一个基于纳米压痕的框架,利用纳米尺度的弹出事件来揭示ecm中位错主导的塑性各向异性。该框架能够定量确定临界分解剪切应力(CRSS)和与位错成核、增殖、迁移和钉-脱钉相关的塑性功。在具有代表性的正交结构ECM中,六氢-1,3,5-三硝基-1,3,5-三嗪(α-RDX),确定了初级滑移系统激活的CRSS为:{011}< 0.01¯>时为35.7±0.3 MPa,{010}<100>时为13.2±0.1 MPa,{110}< 11¯0>时为28.4±0.2 MPa。能量统计分析表明,{010}<100>滑移体系中的位错倍增最能有效地容纳塑性功。本研究建立了一个半定量框架来阐明纳米尺度、位错主导的塑性各向异性和相关的微观能量耗散机制。
From microcracks to fractures: A unified micromechanics-based framework for quasi-brittle failure
Lu Ren, Lunyang Zhao, Yuanming Lai, Qizhi Zhu, Jianfu Shao
doi:10.1016/j.ijplas.2026.104709
从微裂纹到断裂:准脆性破坏的统一微力学框架
The failure of quasi-brittle materials is typically governed by two sequential stages: (i) a diffuse damage phase driven by the accumulation and evolution of microcracks, and (ii) damage localization that culminates in macroscopic fracture. This study proposes a unified micromechanics-based framework that captures the entire failure process, from distributed microcracking to localized fracturing. A micromechanics-based diffuse damage (MDD) model is first developed to characterize pre-localization behavior, in which microcrack-induced inelastic deformation arises from displacement discontinuities across both open and closed microcracks, with frictional sliding considered explicitly in the latter. The transition to localization is defined by a critical microcrack density, representing the onset of coalescence into a dominant fracture. Post-localization behavior is governed by a localized micromechanics-based phase field (LMPF) model, formulated to ensure thermodynamic equivalence with the MDD model. This formulation captures both tensile (mode I) fracture, resulting from microcrack opening, and compressive-shear (mode II) fracture, governed by frictional sliding. The framework’s constitutive behavior is first explored under homogeneous loading conditions and then validated through finite element simulations of representative boundary value problems. The a nalytical and numerical results demonstrate the model’s robustness in reproducing key features of quasi-brittle failure, including nonlinear inelastic deformation, transition to fracture, and fracture propagation across mixed-mode regimes.
准脆性材料的破坏通常由两个连续的阶段控制:(i)由微裂纹的积累和演化驱动的弥散损伤阶段,以及(ii)损伤局部化,最终导致宏观断裂。该研究提出了一个统一的基于微观力学的框架,可以捕获从分布式微裂纹到局部破裂的整个破坏过程。首先建立了基于微力学的弥漫性损伤(MDD)模型来描述预局部化行为,其中微裂纹引起的非弹性变形是由开微裂纹和闭微裂纹之间的位移不连续引起的,后者明确考虑了摩擦滑动。过渡到局部化是由临界微裂纹密度定义的,代表开始合并成主导断裂。后局部化行为由基于局部微力学的相场(LMPF)模型控制,该模型旨在确保与MDD模型的热力学等效。该公式既适用于由微裂纹张开引起的拉伸(I型)断裂,也适用于由摩擦滑动控制的压缩-剪切(II型)断裂。首先探讨了框架在均匀荷载条件下的本构行为,然后通过具有代表性的边值问题的有限元模拟验证了框架的本构行为。分析和数值结果表明,该模型在再现准脆性破坏的关键特征方面具有鲁棒性,包括非线性非弹性变形、向断裂的过渡以及跨混合模式的断裂扩展。