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The effect of stress barriers on unconventional-singularity-driven frictional rupture 应力屏障对非常规晶状体驱动的摩擦断裂的影响
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-25 DOI: 10.1016/j.jmps.2024.105876
Whether or not energy dissipation is localized in the vicinity of the rupture tip, and whether any distal energy dissipation far from the crack tip has a significant influence on rupture dynamics are key questions in the description of frictional ruptures, in particular regarding the application of Linear Elastic Fracture Mechanics (LEFM) to earthquakes. These questions are investigated experimentally using a 40-cm-long experimental frictional interface. Three independent pistons apply a normal load with a fourth piston applying a shear load, enabling the application of a heterogeneous stress state and stress barriers. After loading the frictional interface to a near-critical state, subsequent unloading of one normal-load piston leads to dynamic ruptures which propagate into the heterogeneous stress fields. The ruptures in these experiments are found to be driven by unconventional singularities, characterized by an ever-increasing breakdown work with slip, and as a result do not conform to the assumptions of LEFM. As these experimental stress barriers inhibit slip, they therefore also reduce the breakdown work occurring outside of the cohesive zone. It is shown that this distal weakening, far from the crack tip, must be considered for the accurate prediction of rupture arrest length. These experiments are performed in the context of a proposed stimulation technique for Enhanced Geothermal Systems (EGSs). It has previously been suggested, through theoretical arguments, that stress barriers could be induced through the manipulation of pore pressure such that there is reduced seismic hazard during the shear stimulation of EGSs. This stimulation technique, known as preconditioning, is demonstrated here to reduce the mechanical energy flux to the crack tip, G, while also increasing the fracture energy, Gc. Preconditioning is shown to be capable of arresting seismic rupture and reducing co-seismic slip, slip velocity, and seismic moment at preconditioning stresses which are reasonably achievable in the field. Due to the fully-coupled nature of seismic rupture and fault slip, preconditioning also reduces distal weakening and its contribution to the propagation of induced seismic ruptures. In a similar vein, heterogeneous pore pressure fields associated with some seismic swarms can be used to explain changes in stress drop within the swarm without recourse to material or total-stress heterogeneity.
能量耗散是否集中在断裂尖端附近,以及远离裂缝尖端的远端能量耗散是否对断裂动力学有重大影响,是描述摩擦断裂的关键问题,尤其是线性弹性断裂力学(LEFM)在地震中的应用。我们使用一个 40 厘米长的实验性摩擦界面对这些问题进行了实验研究。三个独立的活塞施加法向载荷,第四个活塞施加剪切载荷,从而实现了异质应力状态和应力屏障的应用。在将摩擦界面加载到接近临界状态后,一个正常加载活塞的后续卸载会导致动态断裂,并传播到异质应力场中。在这些实验中发现,断裂是由非常规奇异点驱动的,其特征是随着滑移不断增加的击穿功,因此不符合 LEFM 的假设。由于这些实验应力屏障会抑制滑移,因此也会减少内聚区外发生的击穿功。实验表明,要准确预测断裂停止长度,必须考虑这种远离裂纹尖端的远端削弱。这些实验是在拟议的强化地热系统(EGSs)激励技术背景下进行的。之前有人通过理论论证提出,可以通过操纵孔隙压力来诱导应力屏障,从而降低 EGSs 剪切激励过程中的地震危害。这种被称为 "预处理"(preconditioning)的激励技术在此被证明可以减少裂缝尖端的机械能通量(G),同时增加断裂能(Gc)。研究表明,在油田可合理达到的预处理应力条件下,预处理技术能够阻止地震破裂,减少共震滑移、滑移速度和地震力矩。由于地震破裂与断层滑移完全耦合,预处理还能减少远端削弱及其对诱发地震破裂传播的影响。同样,与某些地震震群相关的异质孔隙压力场也可用于解释震群内部应力降的变化,而无需求助于材料或总应力异质性。
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引用次数: 0
Analysis of shear localization in viscoplastic solids with pressure-sensitive structural transformations 具有压力敏感结构转换的粘塑性固体中的剪切定位分析
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-25 DOI: 10.1016/j.jmps.2024.105880
Localization, in the form of adiabatic shear, is analyzed in viscoplastic solids that may undergo structural transformation driven by pressure, shear stress, temperature, and magnetic field. As pertinent to polycrystalline metals, transformations may include solid–solid phase transitions, twinning, and dynamic recrystallization. A finite-strain constitutive framework for isotropic metals is used to solve a boundary value problem involving simple shearing with superposed hydrostatic pressure and constant external magnetic field. Three-dimensional theory is reduced to a formulation simple enough to facilitate analysis without advanced numerical methods, yet sophisticated enough to maintain the salient physics. Ranges of constitutive parameters (e.g., strain hardening, strain-rate sensitivity, thermal softening, and strain-driven structure transformation limits influenced by pressure and magnetic field) are obtained for which localization to infinite shear strain is possible. Motivated by experimental and theoretical studies suggesting a non-negligible role of shear on phase transformations in iron (Fe), the model is used to understand influences of pressure and phase transitions on applied strains for which localization should occur in pure Fe and a high-strength steel. Results show, among other trends for the two materials, that shear localization in conjunction with phase transformation is promoted when the transformed phase is softer than the parent phase. Localization that would occur in the isolated parent phase can be mitigated if strain hardening or thermal softening tendencies of the transformed phase are sufficiently increased or reduced, respectively.
以绝热剪切的形式分析了粘塑性固体中的局部化,这种固体可能会在压力、剪切应力、温度和磁场的驱动下发生结构转变。与多晶金属有关的转化可能包括固-固相变、孪晶和动态再结晶。各向同性金属的有限应变构成框架用于求解涉及叠加静水压力和恒定外磁场的简单剪切的边界值问题。三维理论的表述非常简单,无需先进的数值方法即可进行分析,但又足够复杂,以保持突出的物理特性。获得了一系列构成参数(如应变硬化、应变速率敏感性、热软化以及受压力和磁场影响的应变驱动结构转变极限),这些参数可以定位到无限剪切应变。实验和理论研究表明,剪切对铁(Fe)中的相变具有不可忽视的作用,受此启发,该模型被用来了解压力和相变对施加应变的影响,在纯铁和高强度钢中,局部化应该发生在这些应变上。结果表明,这两种材料的其他趋势包括:当转化相比母体相软时,会促进与相变同时发生的剪切局部化。如果转化相的应变硬化或热软化趋势分别得到充分提高或降低,则可减轻孤立母相中出现的局部化现象。
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引用次数: 0
An analytic traction-displacement model for a reinforcing ligament bridging a crack at an arbitrary angle, including elastic, frictional, snubbing, yielding, creep, and fatigue phenomena 以任意角度桥接裂缝的加固韧带的牵引-位移分析模型,包括弹性、摩擦、嗤缩、屈服、蠕变和疲劳现象
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-23 DOI: 10.1016/j.jmps.2024.105879
A micromechanical model is developed that generates analytic expressions for the crack displacement vector u given an arbitrary far-field stress state σa for a crack that is bridged by an array of ligaments oriented at an arbitrary angle with respect to the crack plane. The model is applicable to various materials, e.g., fibrous ceramic composites, or polymer composites reinforced by stitches or z-pins or woven tows, and deals with interfacial friction, enhanced friction due to increased contact pressure (“snubbing”), and the possibility of ligament deflection enabled by yield or damage. The model also conveniently incorporates ligament failure and rate dependent phenomena (fatigue or creep). Adaptability of the model is enabled by the definition of a standard Reference Model, which generates analytic expressions for the crack displacement for given possible yield, ligament deflection, and friction and snubbing effects and is invariant for all geometrical and material choices. The switching on or off and the strengths of all phenomena are governed by assigning values to a handful of material parameters. The material parameters will generally be calibrated against data in a top-down strategy, the model thereby mapping material selection onto engineering fracture via the predicted bridging relationship u[σa]. The relationship u[σa] can depend strongly on bi-angular ligament orientation. Yield and deflection can change u[σa] qualitatively, e.g., by creating fracture surface contact even when σa includes substantial opening tension. Snubbing has significant effects, including possible stabilization of the pullout of a finite ligament. Since model output is computed via analytic expressions, its speed will support the model's use in large-scale material simulations or as constraining physical information in machine learning algorithms.
本研究开发了一种微观力学模型,在给定任意远场应力状态 σa 的情况下,可生成裂纹位移矢量 u 的解析表达式,该裂纹由相对于裂纹平面以任意角度定向的韧带阵列桥接。该模型适用于各种材料,例如纤维状陶瓷复合材料,或通过缝合线、Z 形针或编织丝束加固的聚合物复合材料,并可处理界面摩擦、因接触压力增大("挤压")而增强的摩擦,以及因屈服或损坏而导致韧带变形的可能性。该模型还可方便地纳入韧带失效和速率相关现象(疲劳或蠕变)。标准参考模型可生成给定屈服、韧带挠度、摩擦和挤压效应下裂纹位移的解析表达式,并在所有几何和材料选择下保持不变。所有现象的开启或关闭以及强度都受一些材料参数值的制约。材料参数一般采用自上而下的策略根据数据进行校准,模型通过预测的桥接关系 u[σa] 将材料选择映射到工程断裂上。u[σa]关系在很大程度上取决于双角韧带的方向。屈服和挠曲可以从本质上改变 u[σa],例如,即使 σa 包括很大的张开张力,也会产生断裂面接触。挤压会产生重大影响,包括可能稳定有限韧带的拉伸。由于模型输出是通过解析表达式计算的,其速度将支持模型用于大规模材料模拟或作为机器学习算法中的约束物理信息。
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引用次数: 0
A multiscale Bayesian method to quantify uncertainties in constitutive and microstructural parameters of 3D-printed composites 量化三维打印复合材料构成参数和微结构参数不确定性的多尺度贝叶斯方法
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-23 DOI: 10.1016/j.jmps.2024.105881
3D-printed continuous carbon fiber reinforced composites (CCFRCs) are promising for various engineering applications due to high strength-to-weight ratios and design flexibility. However, the large variations in their mechanical properties pose a considerable challenge to their widespread applications. Here we develop a multiscale Bayesian method to quantify uncertainties in the constitutive parameters and microstructural parameters of 3D-printed CCFRCs. Based on the characterized microstructure of CCFRCs, a multiscale micromechanical model is developed to reveal the relationship between the properties of constituent materials, the microstructural parameters, and the macroscopic constitutive parameters. Furthermore, the joint posterior probability distribution of these parameters is formulated, and the Markov Chain Monte Carlo method (MCMC) is used to compute the posterior distributions of constitutive and microstructural parameters, enabling assessment of parameter uncertainty, correlation, and model calibration error. The inferred microstructural parameters are consistent with those measured by experiments. The posterior predictive distributions of the constitutive response are further computed to validate the probability model. Our method quantifies uncertainties in the constitutive parameters of 3D-printed CCFRCs and identifies their origins, which can optimize constituent material properties and microstructural parameters to achieve more robust composites.
三维打印连续碳纤维增强复合材料(CCFRC)具有高强度重量比和设计灵活性,在各种工程应用中大有可为。然而,其机械性能的巨大差异对其广泛应用构成了相当大的挑战。在此,我们开发了一种多尺度贝叶斯方法,用于量化三维打印 CCFRC 构成参数和微结构参数的不确定性。基于 CCFRC 的微观结构特征,我们建立了一个多尺度微观力学模型,以揭示组成材料的特性、微观结构参数和宏观组成参数之间的关系。此外,还制定了这些参数的联合后验概率分布,并使用马尔可夫链蒙特卡洛方法(MCMC)计算构成参数和微结构参数的后验分布,从而评估参数的不确定性、相关性和模型校准误差。推断出的微观结构参数与实验测量的参数一致。我们进一步计算了结构响应的后验预测分布,以验证概率模型。我们的方法量化了三维打印 CCFRC 构成参数的不确定性,并确定了其来源,从而可以优化组成材料性能和微结构参数,以获得更坚固的复合材料。
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引用次数: 0
Advanced modeling of higher-order kinematic hardening in strain gradient crystal plasticity based on discrete dislocation dynamics 基于离散位错动力学的应变梯度晶体塑性高阶运动硬化高级建模
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-21 DOI: 10.1016/j.jmps.2024.105875
An extensive study of size effects on the small-scale behavior of crystalline materials is carried out through discrete dislocation dynamics (DDD) simulations, intended to enrich strain gradient crystal plasticity (SGCP) theories. These simulations include cyclic shearing and tension-compression tests on two-dimensional (2D) constrained crystalline plates, with single- and double-slip systems. The results show significant material strengthening and pronounced kinematic hardening effects. DDD modeling allows for a detailed examination of the physical origin of the strengthening. The stress–strain responses show a two-stage behavior, starting with a micro-plasticity regime with a steep hardening slope leading to strengthening, and followed by a well-established hardening stage. The scaling exponent between the apparent (higher-order) yield stress and the geometrical size h varies depending on the test type. Scaling relationships of h0.2 and h0.3 are obtained for respectively constrained shearing and constrained tension-compression, aligning with some experimental observations. Notably, the DDD simulations reveal the occurrence of the uncommon type III (KIII) kinematic hardening of Asaro in both single- and double-slip cases, emphasizing the relevance of this hardening type in the realm of small-scale plasticity. Inspired by insights from DDD, two advanced SGCP models incorporating alternative descriptions of higher-order kinematic hardening mechanisms are proposed. The first model uses a Prager-type higher-order kinematic hardening formulation, and the second employs a Chaboche-type (multi-kinematic) formulation. Comparison of these models with DDD simulation results underscores their ability to effectively capture the observed strengthening and hardening effects. The multi-kinematic model, through the use of quadratic and non-quadratic higher-order potentials, shows a notably better qualitative congruence with DDD findings. This represents a significant step towards accurate modeling of small-scale material behaviors. However, it is noted that the proposed models still have limitations, especially in matching the DDD scaling exponents, with both models producing h1 scaling relationships (i.e., Orowan relationship for precipitate size effects). This indicates the need for further improvements in gradient-enhanced theories in order to guarantee their suitability for practical engineering applications.
通过离散位错动力学(DDD)模拟,对晶体材料小尺度行为的尺寸效应进行了广泛研究,旨在丰富应变梯度晶体塑性(SGCP)理论。这些模拟包括二维(2D)受约束晶体板的循环剪切和拉伸压缩试验,以及单滑移和双滑移系统。结果表明材料有明显的强化和运动硬化效应。通过 DDD 建模,可以详细研究强化的物理原因。应力-应变响应显示出两阶段行为,首先是微塑性状态,陡峭的硬化斜率导致强化,随后是成熟的硬化阶段。表观(高阶)屈服应力与几何尺寸 h 之间的比例指数因试验类型而异。对于约束剪切和约束拉伸-压缩,分别得到了 h-0.2 和 h-0.3 的比例关系,这与一些实验观察结果一致。值得注意的是,DDD 模拟揭示了单滑动和双滑动情况下不常见的阿萨罗第三类(KIII)运动硬化的发生,强调了这种硬化类型在小尺度塑性领域的相关性。受 DDD 的启发,我们提出了两个先进的 SGCP 模型,其中包含了对高阶运动硬化机制的替代描述。第一个模型采用了普拉格型高阶运动硬化公式,第二个模型采用了夏波奇型(多运动硬化)公式。将这些模型与 DDD 模拟结果进行比较后,发现它们能够有效捕捉观察到的强化和硬化效应。多运动模型通过使用二次和非二次高阶势能,在质量上与滴滴涕模拟结果的一致性明显提高。这标志着向精确模拟小尺度材料行为迈出了重要一步。然而,我们注意到所提出的模型仍有局限性,特别是在与滴滴涕缩放指数匹配方面,两个模型都产生了 h-1 缩放关系(即沉淀尺寸效应的奥罗恩关系)。这表明需要进一步改进梯度增强理论,以保证其适合实际工程应用。
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引用次数: 0
On the experimental identification of equilibrium relations and the separation of inelastic effects in soft biological tissues 关于软生物组织中平衡关系的实验鉴定和非弹性效应的分离
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-20 DOI: 10.1016/j.jmps.2024.105868
The mechanical characterization of vascular tissues has been mainly focused on the measurement of elastic properties, while the investigation of inelastic effects has received comparatively little attention. Even the relatively simple, purely elastic description of the material behavior requires an appropriate set of experimental data that cannot be easily isolated using standard testing procedures. The presence of viscous and damage-related phenomena poses some challenges in the definition of appropriate testing protocols capable of identifying an equilibrium response, which in general does not solely represent the elastic material behavior. The primary goal of the present study is therefore to devise an experimental procedure that can distinguish and evaluate the different constitutive phenomena separately. To this end, we apply methodologies widely used in the mechanical testing of rubber-like materials and transfer them to the field of biomechanics. We performed two types of experiments in equibiaxial extension on porcine thoracic aorta: a continuous cyclic test followed by a single-step relaxation test and a cyclic multi-step relaxation test, each at varying stretch rates. We demonstrate that the approximation of quasi-stationarity through continuous testing at slow rates is inadequate for the identification of an equilibrium relation. Alternatively, a step-wise protocol allows for the separation of equilibrium and viscous effects. This motivates a thermodynamic discussion of the experimental results in terms of energy dissipation and a closer look at the interplay of inelastic phenomena.
血管组织的力学特征主要集中在弹性特性的测量上,而对非弹性效应的研究则相对较少。即使是相对简单的纯弹性材料行为描述,也需要一组适当的实验数据,而这些数据无法通过标准测试程序轻易分离出来。粘性和损伤相关现象的存在给确定适当的测试方案带来了一些挑战,这些方案能够确定平衡响应,而平衡响应一般并不完全代表材料的弹性行为。因此,本研究的主要目标是设计一种实验程序,能够区分并分别评估不同的构成现象。为此,我们采用了广泛应用于橡胶类材料力学测试的方法,并将其应用于生物力学领域。我们对猪胸主动脉进行了两类等轴伸展试验:连续循环试验后的单步松弛试验和循环多步松弛试验,每种试验的拉伸速率各不相同。我们证明,通过慢速率连续测试来接近准稳态,不足以确定平衡关系。另一种方法是采用分步方案,将平衡效应和粘性效应分开。这促使我们从能量耗散的角度对实验结果进行热力学讨论,并对非弹性现象的相互作用进行更深入的研究。
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引用次数: 0
Exponential time propagators for elastodynamics 弹性力学的指数时间传播者
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-20 DOI: 10.1016/j.jmps.2024.105871
We propose a computationally efficient and systematically convergent approach for elastodynamics simulations. We recast the second-order dynamical equation of elastodynamics into an equivalent first-order system of coupled equations, so as to express the solution in the form of a Magnus expansion. With any spatial discretization, it entails computing the exponential of a matrix acting upon a vector. We employ an adaptive Krylov subspace approach to inexpensively and accurately evaluate the action of the exponential matrix on a vector. In particular, we use an apriori error estimate to predict the optimal Krylov subspace size required for each time-step size. We show that the Magnus expansion truncated after its first term provides quadratic and superquadratic convergence in the time-step for nonlinear and linear elastodynamics, respectively. We demonstrate the accuracy and efficiency of the proposed method for one linear (linear cantilever beam) and three nonlinear (nonlinear cantilever beam, soft tissue elastomer, and hyperelastic rubber) benchmark systems. For a desired accuracy in energy, displacement, and velocity, our method allows for 10100× larger time-steps than conventional time-marching schemes such as Newmark-β method. Computationally, it translates to a 1000× and 10100× speed-up over conventional time-marching schemes for linear and nonlinear elastodynamics, respectively.
我们提出了一种计算高效、系统收敛的弹性动力学模拟方法。我们将弹性动力学的二阶动力学方程重构为一个等效的一阶耦合方程系统,从而以马格努斯展开的形式表达解。在任何空间离散化的情况下,都需要计算矩阵作用于矢量的指数。我们采用自适应克雷洛夫子空间方法,以低成本准确评估指数矩阵对矢量的作用。特别是,我们使用先验误差估计来预测每个时间步长所需的最佳 Krylov 子空间大小。我们证明,在第一项之后截断的马格努斯展开分别为非线性和线性弹性力学提供了二次收敛和超二次收敛的时间步长。我们对一个线性(线性悬臂梁)和三个非线性(非线性悬臂梁、软组织弹性体和超弹性橡胶)基准系统演示了所提方法的准确性和效率。对于所需的能量、位移和速度精度,我们的方法允许的时间步长比 Newmark-β 方法等传统时间行进方案大 10-100 倍。在计算方面,与线性和非线性弹性动力学的传统时间行进方案相比,我们的方法分别提高了 1000 倍和 10-100 倍的速度。
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引用次数: 0
Modeling of textile composite using analytical network-averaging and gradient damage approach 使用分析网络平均法和梯度损伤法建立纺织复合材料模型
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-20 DOI: 10.1016/j.jmps.2024.105874
In this contribution, we present a gradient damage model for anisotropic textile reinforcements including fiber inextensibility and fiber sliding. In contrast to previous works, the gradient damage formulation stems not from a numerical regularization basis but from the thermodynamics of internal variables. It results in a nonlocal term as the internal energy of fiber bending with measurable nonlocal parameter. Furthermore, to guarantee a priori that rotations and reflections determined by orthogonal tensors among the symmetry group do not affect the response function of the anisotropic constitutive law, a novel mesoscopic kinematic measure for the representative volume element of the fabric is defined on the basis of the analytical network-averaging concept. Such kinematic measure is of crucial importance for material modeling of damage-elastoplasticity in anisotropic textile reinforcements, and allows for analytical descriptions of inter- and intra-ply sliding of fibers. A mixed finite element formulation is then presented for textile reinforcements taking into account fiber inextensibility. The predictive capability of the computational model is demonstrated by comparing with multiple experimental datasets of dry textile fabrics.
在这篇论文中,我们提出了一种各向异性纺织加固材料的梯度损伤模型,其中包括纤维非伸张性和纤维滑动。与以往的研究不同,梯度损伤模型的建立不是基于数值正则化,而是基于内部变量的热力学。它产生了一个非局部项,即具有可测量非局部参数的纤维弯曲内能。此外,为了事先保证由对称组间正交张量决定的旋转和反射不会影响各向异性结构定律的响应函数,我们在分析网络平均概念的基础上,为织物的代表性体积元素定义了一种新的介观运动测量方法。这种运动学度量对于各向异性织物加固材料的损伤-持久塑性建模至关重要,并可对纤维的层间和层内滑动进行分析描述。然后,考虑到纤维的不可伸缩性,提出了纺织加固材料的混合有限元计算方法。计算模型的预测能力通过与多个干纺织品实验数据集的比较得到了证明。
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引用次数: 0
Electroactive differential growth and delayed instability in accelerated healing tissues 加速愈合组织中的电活性差异生长和延迟不稳定性
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-19 DOI: 10.1016/j.jmps.2024.105867

Guided by experiments contrasting electrically accelerated recovery with natural healing, this study formulates a model to investigate the importance of electroactive differential growth and morphological changes in tissue repair. It underscores the clinical potential of leveraging electroactive differential growth for improved healing outcomes. The study reveals that voltage stimulation significantly enhances the healing and growth of biological tissues, accelerating the regeneration process across various growth modalities and steering towards isotropic growth conditions that do not favor any specific growth pathways. Enhancing the electroelastic coupling parameters improves the efficacy of bioelectric devices, initiating contraction and fortification of biological tissues in alignment with the electric field. This process facilitates swift cell migration and proliferation, as well as oriented growth of tissue. In instances of strain stiffening at elevated strains, the extreme critical growth ratio aligns with the predictions of neo-Hookean models. Conversely, for tissues experiencing strain stiffening under moderate to very low strain conditions, the strain stiffening effect substantially delays the onset of electroelastic growth instability, ultimately producing a smooth, hyperelastic surface devoid of any unstable morphologies. Our investigation, grounded in nonlinear electroelastic field and perturbation theories, explores how electric fields influence differential growth and instability in biological tissues. We examine the interactions among dimensionless voltage, internal pressure, electroelastic coupling, radius ratio, and strain stiffening, revealing their effects on promoting growth and delaying instability. This framework offers insights into the mechanisms behind electroactive growth and its instabilities, contributing valuable knowledge to the tissue healing.

在电加速恢复与自然愈合对比实验的指导下,本研究建立了一个模型来研究电活性差异生长和形态变化在组织修复中的重要性。它强调了利用电活性差异生长改善愈合效果的临床潜力。研究显示,电压刺激能显著增强生物组织的愈合和生长,加速各种生长模式的再生过程,并引导各向同性的生长条件,而不偏向于任何特定的生长途径。增强电弹性耦合参数可提高生物电设备的功效,启动生物组织的收缩和强化,使其与电场保持一致。这一过程有利于细胞的快速迁移和增殖,以及组织的定向生长。在高应变僵化的情况下,极端临界生长比符合新胡克模型的预测。相反,对于在中等应变到极低应变条件下出现应变硬化的组织,应变硬化效应大大推迟了电弹性生长不稳定性的发生,最终产生一个光滑的、没有任何不稳定形态的超弹性表面。我们的研究以非线性电弹性场和扰动理论为基础,探讨了电场如何影响生物组织的差异生长和不稳定性。我们研究了无量纲电压、内部压力、电弹性耦合、半径比和应变硬化之间的相互作用,揭示了它们对促进生长和延迟不稳定性的影响。这一框架深入揭示了电活性生长及其不稳定性背后的机制,为组织愈合贡献了宝贵的知识。
{"title":"Electroactive differential growth and delayed instability in accelerated healing tissues","authors":"","doi":"10.1016/j.jmps.2024.105867","DOIUrl":"10.1016/j.jmps.2024.105867","url":null,"abstract":"<div><p>Guided by experiments contrasting electrically accelerated recovery with natural healing, this study formulates a model to investigate the importance of electroactive differential growth and morphological changes in tissue repair. It underscores the clinical potential of leveraging electroactive differential growth for improved healing outcomes. The study reveals that voltage stimulation significantly enhances the healing and growth of biological tissues, accelerating the regeneration process across various growth modalities and steering towards isotropic growth conditions that do not favor any specific growth pathways. Enhancing the electroelastic coupling parameters improves the efficacy of bioelectric devices, initiating contraction and fortification of biological tissues in alignment with the electric field. This process facilitates swift cell migration and proliferation, as well as oriented growth of tissue. In instances of strain stiffening at elevated strains, the extreme critical growth ratio aligns with the predictions of neo-Hookean models. Conversely, for tissues experiencing strain stiffening under moderate to very low strain conditions, the strain stiffening effect substantially delays the onset of electroelastic growth instability, ultimately producing a smooth, hyperelastic surface devoid of any unstable morphologies. Our investigation, grounded in nonlinear electroelastic field and perturbation theories, explores how electric fields influence differential growth and instability in biological tissues. We examine the interactions among dimensionless voltage, internal pressure, electroelastic coupling, radius ratio, and strain stiffening, revealing their effects on promoting growth and delaying instability. This framework offers insights into the mechanisms behind electroactive growth and its instabilities, contributing valuable knowledge to the tissue healing.</p></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0022509624003338/pdfft?md5=aa01c5c4efb6b09e119d483a6617f63d&pid=1-s2.0-S0022509624003338-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Data-driven bio-mimetic composite design: Direct prediction of stress–strain curves from structures using cGANs 数据驱动的生物仿真复合材料设计:利用 cGANs 直接预测结构的应力-应变曲线
IF 5 2区 工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-18 DOI: 10.1016/j.jmps.2024.105857
Designing high-performance composites requires integrating tasks, including material selection, structural arrangement, and mechanical property characterization. Accurate prediction of composite mechanical properties requires a comprehensive understanding of their mechanical response, particularly the failure mechanisms under high deformations. As traditional computational methods struggle to exhaustively explore every composite configuration in the vast design space for optimal design search, machine learning offers rapid identification of optimal composite designs. This study presents a cGAN-based deep learning model for predicting stress–strain curves directly from composite structures using an image-to-vector approach. The model incorporates fully connected layers within a U-Net generator for stress–strain curve generation and utilizes a PatchGAN discriminator for realism assessment. This end-to-end mapping from structures to mechanical response effectively eliminates the need for extensive simulations and labor-intensive post-analyses. Phase-field simulations were conducted to model the material failure process, generating stress–strain curves for various composite structures used as ground truth data to train and test the surrogate model. This study incorporates various composite structures in the dataset, including random (RS), layered (LS), chessboard-like (CS), soft-scaffold (SS), and hard-scaffold (HS), enhancing the representation of design diversity. Despite being trained on a limited dataset (approximately 1.5% for each bio-mimetic structure and 1072% for RS composites), the model achieves highly accurate predictions in stress–strain curves, with MAE loss converging to 0.01 for training and 0.05 for testing after 2 million iterations. High evaluation scores on training data (R2>0.997, MAPE <1.08%) and testing data (R2>0.946, MAPE <5.53%) demonstrate the model’s accuracy in predicting mechanical properties such as Young’s modulus, strength, and toughness across all composite structures. Overall, the study provides a proof of concept for using machine learning to simplify the design process, demonstrating its potential for solving inverse composite design problems.
高性能复合材料的设计需要综合多项任务,包括材料选择、结构布置和机械性能表征。要准确预测复合材料的机械性能,就必须全面了解其机械响应,特别是高变形下的失效机理。传统的计算方法难以在广阔的设计空间中穷尽地探索每一种复合材料构型,从而进行最佳设计搜索,而机器学习可快速识别最佳复合材料设计。本研究提出了一种基于 cGAN 的深度学习模型,利用图像到向量方法直接预测复合材料结构的应力-应变曲线。该模型在用于生成应力应变曲线的 U-Net 生成器中加入了全连接层,并利用 PatchGAN 识别器进行真实性评估。这种从结构到机械响应的端到端映射有效地消除了大量模拟和劳动密集型后期分析的需要。通过相场模拟来模拟材料的失效过程,生成各种复合材料结构的应力-应变曲线,作为训练和测试代用模型的基本真实数据。这项研究在数据集中纳入了各种复合材料结构,包括随机结构(RS)、分层结构(LS)、棋盘式结构(CS)、软支架结构(SS)和硬支架结构(HS),从而增强了设计多样性的代表性。尽管该模型只在有限的数据集上进行了训练(每种仿生物结构的数据集约为 1.5%,RS 复合材料的数据集约为 10-72%),但它对应力-应变曲线的预测非常准确,经过 200 万次迭代后,训练的 MAE 损失趋近于 0.01,测试的 MAE 损失趋近于 0.05。在训练数据(R2>0.997,MAPE <1.08%)和测试数据(R2>0.946,MAPE <5.53%)上的高评估分数证明了该模型在预测所有复合材料结构的机械性能(如杨氏模量、强度和韧性)方面的准确性。总之,这项研究证明了使用机器学习简化设计流程的概念,展示了其解决反向复合材料设计问题的潜力。
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Journal of The Mechanics and Physics of Solids
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