Mechanics of Materials最新文献_第7页

Anisotropy of the fracture toughness in β-HMX crystals: A computational study

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2025-01-08 DOI: 10.1016/j.mechmat.2025.105242

Camilo A. Duarte , Catalin R. Picu , Vikas Tomar , WaiChing Sun

The reliability, stability, and secure handling of

β

-cyclo-tetramethylene tetranitramine (

β

-HMX) crystals, a high explosive (HE) material commonly used in polymer-bonded explosives (PBX), depend heavily on their fracture properties. Cracks in HE crystals are known to localize temperature or form hotspots due to interfacial friction and can also facilitate the propagation of chemical reactions, leading to early ignition and initiation. Hence, to develop safe and reliable HEs, it is essential to characterize the fracture toughness of

β

-HMX, which is believed to be highly anisotropic. Furthermore, it is important to understand the origin of fracture anisotropy in HMX crystals, which is hypothesized to depend not only on the surface energy of the fracture plane, as it occurs in brittle fracture, but also on plastic deformation due to crystallographic slip. For this purpose, we performed finite element simulations of single

β

-HMX crystals under Mode I deformation with an atomistic-informed crystal plasticity model. Fracture toughness is estimated computationally for crystals with cracks oriented in different directions using the J-integral method. Our results confirm that the fracture toughness of HMX is highly dependent on the crystal orientation, owing to both elastic and plastic anisotropy. Furthermore, we conclude that although brittle HMX crystals may not sustain extensive plastic deformation, the contribution of plasticity to the fracture toughness is not negligible, and the anisotropy of the plastic deformation should not be neglected.

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引用次数: 0

Exploring mechanical damage in fascia: Experiments and advanced constitutive modeling approaches

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2025-01-08 DOI: 10.1016/j.mechmat.2025.105239

Alejandro Aparici-Gil , Marta M. Pérez , Estefanía Peña

Biological tissues exhibit complex structures that necessitate mechanical models incorporating details of their key components and the physical processes occurring within the material. Our objective is to enhance the understanding of damage mechanisms in fibered tissues through mechanical testing. This includes conducting uniaxial tensile tests on fascia beyond physiological stretch limits and developing two constitutive models to describe damage and rupture. These models integrate both phenomenological and microstructural perspectives.

Two perpendicular directions, corresponding to the two families of collagen fibers, were compared: the longitudinal direction, characterized by greater stiffness, and the transverse direction. The mean Cauchy rupture stress (

σ_{r}

) was reported as 16.67 for the longitudinal direction and 4.76 MPa for the transverse direction, with a significant difference observed between them (

p

-value

<

0.05). Similarly, a significant difference in stored strain energy was found between the two directions (

p

-value

<

0.05) between directions, being in longitudinal equal to 1.33

N \cdot mm / {mm}^{3}

and 0.49 in transversal one. However, rupture stretches (

λ_{r}

) did not exhibit a significant difference (

p

-value

>

0.05) with values of 1.17 and 1.22 for the longitudinal and transverse directions, respectively.

In this study, a hyperelastic constitutive model for fascia was modified to incorporate damage effects into the strain energy function. Additionally, an extended version of a microstructural damage model was developed to effectively replicate the experimental data. The proposed damage models successfully captured the stress–strain behavior and accurately represented the damage process. The coefficient of determination

R^{2}

for the fitted data ranged from 0.616 to 0.973, except for Sample IV, which exhibited an

R^{2}

value of 0.251 when using the phenomenological model. In all cases, the microstructural model provided a more accurate fit compared to the phenomenological model, with

R^{2}

values ranging from 0.748 to 0.927.

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引用次数: 0

Micromechanics-based numerical analysis of failure in calcified abdominal aortic aneurysm

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2025-01-08 DOI: 10.1016/j.mechmat.2025.105241

Jaynandan Kumar, Anshul Faye

Abdominal aortic aneurysms (AAAs) are a critical medical concern characterized by the dilation of the abdominal aorta, with the potential for life-threatening rupture. Calcification of AAAs in varying amount is identified as one of the factors affecting their mechanical and failure behaviour. However, reasons behind the same are not clear. The current work presents a micro-mechanics based numerical method to analyse the effect of calcification on the rupture behaviour of aneurysmatic tissue. An anisotropic material model suitable for modelling biological tissues is used and it is calibrated against available experimental data under bi-axial loading. To model failure in tissues, an energy-based failure criterion is used and failure parameters are identified from available experimental data. Calcified tissues are modelled as a composite material with tissue as a matrix and calcium (Ca) particles as an inclusion. Multiple representative volume elements are generated and used for simulation to capture the effect of morphology and amount of calcification. Contact conditions between the tissue and Ca particles are also assumed for the investigation. Thus, failure envelopes of calcified tissues are generated under different conditions. Our findings reveal that calcification affects the aneurysm rupture significantly. Amount of calcification is more critical than its morphology. Highly calcified tissues fail at lower stretches and the failure initiates in the ligaments joining Ca particles. Failure location could be correlated with available experimental observations. With higher calcification, tissues also become more isotropic in nature. The study also emphasizes that stretch-based criterion is a better candidate for predicting the failure of the aneurysm than a stress-based criterion. Further, parameters for constitutive model and failure model are identified for homogenized calcified tissue with low calcification.

腹主动脉瘤（AAA）是一种严重的医学问题，其特点是腹主动脉扩张，破裂后可能危及生命。AAA 不同程度的钙化被认为是影响其机械和失效行为的因素之一。然而，其背后的原因尚不清楚。本研究提出了一种基于微观力学的数值方法，用于分析钙化对动脉瘤组织破裂行为的影响。该方法采用了适合生物组织建模的各向异性材料模型，并根据双轴加载下的现有实验数据进行了校准。为了模拟组织的失效，采用了基于能量的失效准则，并根据现有实验数据确定了失效参数。钙化组织被模拟为一种复合材料，以组织为基体，钙（Ca）颗粒为内含物。生成多个代表性体积元素并用于模拟，以捕捉形态和钙化量的影响。研究中还假设了组织和钙颗粒之间的接触条件。因此，钙化组织的破坏包络线是在不同条件下生成的。我们的研究结果表明，钙化对动脉瘤破裂的影响很大。钙化量比钙化形态更为重要。钙化程度高的组织在较低的拉伸强度下就会发生破裂，并且破裂始于连接钙颗粒的韧带。失效位置与现有的实验观察结果相关。钙化程度越高，组织的各向同性越强。研究还强调，与基于应力的标准相比，基于拉伸的标准更适合预测动脉瘤的破坏。此外，还确定了低钙化度均质钙化组织的构成模型和破坏模型参数。

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引用次数: 0

Enhancing robustness in machine-learning-accelerated molecular dynamics: A multi-model nonparametric probabilistic approach

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2025-01-04 DOI: 10.1016/j.mechmat.2024.105237

Ariana Quek , Niuchang Ouyang , Hung-Min Lin , Olivier Delaire , Johann Guilleminot

In this work, we present a system-agnostic probabilistic framework to quantify model-form uncertainties in molecular dynamics (MD) simulations based on machine-learned (ML) interatomic potentials. Such uncertainties arise from the design and selection of ML potentials, as well as from training aspects pertaining to the definition of datasets and calibration strategies. Our approach relies on a stochastic reduced-order model (SROM) where the approximation space is expanded through the randomization of the projection basis. The construction of the underlying probability measure is achieved in the context of information theory, by leveraging the existence of multiple model candidates, corresponding to different ML potentials for instance. To assess the effectiveness of the proposed approach, the method is applied to capture model-form uncertainties in a sodium thiophosphate system, relevant to sodium-ion-state batteries. We demonstrate that the SROM accurately encodes model uncertainties from different ML potentials – including a Neuro-Evolution Potential (NEP) and a Moment Tensor Potential (MTP) – and can be used to propagate these uncertainties to macroscopic quantities of interest, such as ionic diffusivity. Additionally, we investigate the impact of augmenting the snapshot matrix with momenta, and of introducing a frequency-based split in the construction of the random projection matrix. Results indicate that including momenta improves the accuracy of the SROM, while frequency splitting enables stabilization around nominal responses during uncertainty propagation. The proposed enhancements contribute to more robust and stable predictions in MD simulations involving ML potentials.

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引用次数: 0

The bending-buckling coupled model for blistering behavior in anti-corrosion coatings

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2025-01-02 DOI: 10.1016/j.mechmat.2024.105238

Liangji Ma , Yin Yao , Bo Zhang , Zhilong Peng , Shaohua Chen

Anti-corrosion coatings are widely applied in marine engineering and marine equipment. Understanding their blistering failure mechanisms is vital for optimizing coating designs and extending their service life. This paper develops a bending-buckling coupled model and employs the Rayleigh-Ritz method to investigate the axisymmetric circular blister of coatings with initial deflections, with a special focus on the situation where the transverse load is opposite to the deflection. By incorporating the chemo-mechanical coupling, an analytical solution of the critical buckling load in terms of diffusion strain is well achieved, concisely explaining the impacts of transverse loads, initial deflections, and aspect ratios on the critical buckling load. The influence of these parameters on the post-buckling behavior of the coating is further discussed and the contour of the coating blister can be presented. The results should have theoretical guidance significance for predicting and analyzing the service behavior of anti-corrosion coatings.

引用次数: 0

An additive Mori–Tanaka scheme for elastic–viscoplastic composites based on a modified tangent linearization

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2025-01-01 DOI: 10.1016/j.mechmat.2024.105191

K. Kowalczyk-Gajewska , S. Berbenni , S. Mercier

Mean-field modeling based on the Eshelby inclusion problem poses some difficulties when the non-linear Maxwell-type constitutive law is used for elasto–viscoplasticity. One difficulty is that this behavior involves different orders of time differentiation, which leads a long-term memory effect. One of the possible solutions to this problem is the additive interaction law. Generally, mean field models solely use the mean values of stress and strain fields per phase, while variational approaches consider the second moments of stresses and strains. It is seen that the latter approach improves model predictions allowing to account for stress fluctuation within the phases. However, the complexity of the variational formulations still makes them difficult to apply in the large scale finite element calculations and for non-proportional loadings. Thus, there is a need to include the second moments within homogenization models based on the additive interaction law. In the present study, the incorporation of the second moments of stresses into the formulation of the additive Mori–Tanaka model of two-phase elastic–viscoplastic material is discussed. A modified tangent linearization of the viscoplastic law is proposed, while the Hill–Mandel’s lemma is used to track the evolution of second moments of stresses. To study the model performance and efficiency, the results are compared to the full-field numerical calculations and predictions of other models available in the literature. Very good performance of the modified tangent linearization is demonstrated from these benchmarks for both monotonic and non monotonic loading responses.

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引用次数: 0

Identification for elastoplastic constitutive parameters of 316L stainless steel lattice structures using finite element model updating and integrated digital image correlation

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-12-25 DOI: 10.1016/j.mechmat.2024.105232

Zhaozhen Huang, Caroline Antion, Franck Toussaint

Lattice structures are widely considered for industrial applications owing to their excellent energy absorption and mechanical properties. In this work, octet-truss lattice structures are manufactured from 316L stainless steel powder by selective laser melting (SLM). The geometrical information of lattice structures is captured by SEM and X-ray tomography. It reveals that realistic dimensions of struts differ slightly from CAD-designed ones. The mechanical behaviors are investigated both experimentally and numerically. Quasi-static uni-axial compression experiments with 2D digital image correlation (DIC) technology are conducted to measure displacement/strain fields. Finite element analysis based on an elastic and anisotropic plastic constitutive model is used to simulate mechanical behaviors. To improve the predictive accuracy, a finite element model updating approach is implemented to identify constitutive parameters. The results show that numerical simulation with optimized parameters match well with experiments in aspect of force-displacement curve at elastic–plastic stage and displacement fields.

晶格结构因其出色的能量吸收和机械性能而被广泛应用于工业领域。在这项工作中，利用选择性激光熔化（SLM）技术，用 316L 不锈钢粉末制造出了八叉桁架晶格结构。通过扫描电子显微镜和 X 射线断层扫描捕捉了晶格结构的几何信息。结果表明，支柱的实际尺寸与 CAD 设计的尺寸略有不同。实验和数值研究了机械行为。利用二维数字图像相关（DIC）技术进行了准静态单轴压缩实验，以测量位移/应变场。基于弹性和各向异性塑性组成模型的有限元分析用于模拟机械行为。为了提高预测精度，采用了一种有限元模型更新方法来确定构成参数。结果表明，在弹塑性阶段的力-位移曲线和位移场方面，采用优化参数的数值模拟与实验结果非常吻合。

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引用次数: 0

Relating stiffness changes in porous materials to the evolution of pore space

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-12-24 DOI: 10.1016/j.mechmat.2024.105236

Yulia Pronina , Maria Narykova , Mark Kachanov

The work aims at relating stiffness changes in porous materials to the evolution of pore space geometry. After a brief review of the relevant micromechanics tools, we apply them to case studies on several metals. In particular, it is clarified, when porosity can or cannot be used as a single quantitative characteristic of the pore space in whose terms the effective stiffness is to be expressed, and when it must be changed to crack density. Namely, the use of porosity parameter is legitimate in cases of isotropic mixtures of pores having approximately equal shape factors, provided the shapes are not strongly oblate (aspect ratios larger than about 0.08). Considered examples show that, in cases of strongly oblate, crack-like pores, noticeable stiffness changes may occur at very low values of porosity; in such cases, the crack density parameter must be used. Besides predicting the effective stiffness in terms of proper characteristics of the pore space, the developed methodology allows monitoring the evolution of pore shapes based on stiffness changes and porosity data. In our analysis, pore geometries are modeled by spheroids of appropriate aspect ratios; they provide sufficient flexibility and allow quantitative modeling. The adequacy of such modeling is supported by agreement of the theoretical results with experimental data.

这项工作旨在将多孔材料的刚度变化与孔隙空间几何形状的演变联系起来。在简要回顾了相关的微观力学工具后，我们将其应用于几种金属的案例研究。我们特别澄清了孔隙度何时可以或何时不可以作为孔隙空间的单一定量特征来使用，而有效刚度则必须用裂纹密度来表示。也就是说，在各向同性孔隙混合物的形状系数大致相同的情况下，使用孔隙度参数是合理的，前提是孔隙的形状不是强烈扁圆形（长宽比大于 0.08）。考虑过的实例表明，在孔隙呈强扁圆形、裂缝状的情况下，孔隙度值很低时也会出现明显的刚度变化；在这种情况下，必须使用裂缝密度参数。除了根据孔隙空间的适当特征预测有效刚度外，所开发的方法还可以根据刚度变化和孔隙率数据监测孔隙形状的演变。在我们的分析中，孔隙几何形状是通过适当长宽比的球体来建模的；这些球体具有足够的灵活性，可以进行定量建模。理论结果与实验数据的一致性证明了这种建模的充分性。

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引用次数: 0

Homogenised modelling of the electro-mechanical behaviour of a vascularised poroelastic composite representing the myocardium

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-12-20 DOI: 10.1016/j.mechmat.2024.105215

Laura Miller , Raimondo Penta

We propose a novel model for a vascularised poroelastic composite representing the myocardium which incorporates both mechanical deformations and electrical conductivity. Our structure comprises a vascularised poroelastic extracellular matrix with an embedded elastic inclusions (representing the myocytes) and we consider the electrical conductance between these two solid compartments. There is a distinct lengthscale separation between the scale where we can visibly see the connected fluid compartment separated from the poroelastic matrix and the elastic myocyte and the overall size of the heart muscle. We therefore apply the asymptotic homogenisation technique to derive the new model. The effective governing equations that we obtain describe the behaviour of the myocardium in terms of the zero-th order stresses, current densities, relative fluid–solid velocities, pressures, electric potentials and elastic displacements. It effectively accounts for the fluid filling in the pores of the poroelastic matrix, flow in the vessels, the transport of fluid between the vessels and the matrix, and the elastic deformation and electrical conductance between the poroelastic matrix and the myocyte. This work paves the way towards a myocardium model that incorporates multiscale deformations and electrical conductivity whilst also considering the effects of the vascularisation and indeed the impact on mechanotransduction.

我们提出了一种代表心肌的血管化孔弹性复合材料的新模型，该模型同时包含机械变形和导电性。我们的结构包括一个血管化的多孔弹性细胞外基质和一个嵌入式弹性内含物（代表心肌细胞），我们考虑了这两个固体部分之间的导电性。在我们能明显看到从孔弹性基质和弹性肌细胞中分离出来的连接液体区块的尺度与心肌的整体尺寸之间存在明显的长度尺度差异。因此，我们采用渐近均质化技术来推导新模型。我们得到的有效控制方程通过零阶应力、电流密度、流固相对速度、压力、电动势和弹性位移来描述心肌的行为。它有效地解释了孔弹性基质孔隙中的流体填充、血管中的流动、血管与基质之间的流体传输以及孔弹性基质与心肌细胞之间的弹性变形和电导。这项工作为建立心肌模型铺平了道路，该模型包含了多尺度变形和导电性，同时还考虑了血管的影响以及对机械传导的影响。

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引用次数: 0

Critical exposure time for panel paintings due to change in environmental conditions

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-12-19 DOI: 10.1016/j.mechmat.2024.105234

Pietro Foti , America Califano , Chao Gao , Raffaele Sepe , Chiara Bertolin , Filippo Berto

Balancing the preservation of historical collections with energy consumption related to climate control is vital in museums and historical buildings to reduce carbon footprints. This is especially important for the structural integrity of hygroscopic objects like panel paintings, which are susceptible to damage from environmental changes. To address these challenges, a Finite Element (FE) hygro-mechanical-uncoupled model has been developed to assess the safety of panel paintings under changing environmental conditions, specifically changes in relative humidity (RH%) at a constant temperature (T). The model, similar to a thermal problem, uses material parameters from literature expressed consistently with RH as the driving potential. It evaluates scenarios involving panel paintings with different wood supports (Pine and Poplar) subjected to abrupt environmental changes, with or without moisture exchange through the gesso layer. This simulation approach investigates the environmental effects and their temporal evolution on panel paintings. The main outcome is the evaluation of the critical exposure time for a panel painting to experience new damage, particularly in the gesso layer, due to internal cracks.

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引用次数: 0