Experimental Mechanics最新文献_第5页

Thermal Stress Analysis for Functionally Graded Plates with Modulus Gradation, Part II 模量分级功能分级板的热应力分析，第二部分

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-06-27 DOI: 10.1007/s11340-024-01091-9

T. Baytak, M. Tosun, C. Ipek, C. Mollamahmutoglu, O. Bulut

Background

The gradation of thermal expansion coefficient was analyzed in the earlier study. The analytical formulation derived here, which is quite different, should be validated to understand the thermal stress distribution in a laminated composite and functionally graded material. Besides this solution, a validated numerical model can also be used to optimize the material gradation of plates in terms of sustainability.

Objective

To validate the analytical formulation derived here, an experimental model is presented to understand the thermal stress concentration for functionally graded and laminated composite plates. A numerical model is also validated to extend to understand the effects of the number of layers, the thickness of a layer, the gradation function, the ratio of elastic moduli, and the coating.

Methods

The experimental problems in the production of the experimental models with layers of different elastic moduli are discussed here. In the experimental analysis, a three-dimensional photoelastic stress analysis of two- and four-layer composite plate was used to mechanically model the thermal expansion. The analytical solution for the thermal stress in a free plate was derived by the strain suppression method based on the principle of superposition. The numerical models were analyzed using finite element software. The step variation in the experiment was used as a reference point for a continuous or multi-layer (> 2) step variation of material coefficients in the models.

Results

The variation of stress concentration is shown for various cases of laminated and continuous gradations of elastic modulus. The four-layer experimental model provides the difference in thermal stress distribution as a result of a layered coating. The validated analytical and numerical models provide reasonable results. An empirical formula to optimize the material gradation in terms of elastic modulus is derived.

Conclusions

The experimental model can be used to analyze thermal stress in functionally graded materials. The gradations of the material in the plate or the coating of the plates can be optimized by the validated analytical and numerical models. The empirical formula can be used to determine the elastic modulus of the coating to minimize the stress concentration.

背景早先的研究分析了热膨胀系数的分级。本文得出的分析公式与之大相径庭，应加以验证，以了解层压复合材料和功能分级材料中的热应力分布。为了验证本文得出的分析公式，本文提出了一个实验模型，以了解功能分级和层压复合板的热应力集中情况。同时还验证了一个数值模型，以扩展了解层数、层厚、分级函数、弹性模量比和涂层的影响。方法这里讨论了在制作具有不同弹性模量层的实验模型时遇到的实验问题。在实验分析中，使用了二层和四层复合板的三维光弹性应力分析来建立热膨胀的力学模型。自由板中热应力的解析解是通过基于叠加原理的应变抑制法得出的。数值模型使用有限元软件进行分析。实验中的阶跃变化被用作模型中材料系数连续或多层（> 2）阶跃变化的参考点。四层实验模型提供了分层涂层导致的热应力分布差异。经过验证的分析和数值模型提供了合理的结果。结论实验模型可用于分析功能分级材料中的热应力。通过验证分析和数值模型，可以优化板材或板材涂层中的材料级配。经验公式可用于确定涂层的弹性模量，以尽量减少应力集中。

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引用次数: 0

User-Independent, Accurate and Pixel-Wise DIC Measurements with a Task-Optimized Neural Network 利用任务优化神经网络进行与用户无关、精确且像素化的 DIC 测量

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-06-26 DOI: 10.1007/s11340-024-01088-4

B. Pan, Y. Liu

Background

Being an image-based optical technique for full-field deformation measurements, the ultimate purpose of digital image correlation (DIC) is to realize accurate, precise and pixel-wise displacement/strain measurements in a full-automatic manner without users’ inputs.

Objective

In this work, we propose a task-optimized neural network, called RAFT-DIC, to achieve user-independent, accurate and pixel-wise displacement field measurements.

Methods

RAFT-DIC is based on the state-of-the-art optical flow architecture: Recurrent All-Pairs Field Transforms (RAFT). We make two targeted improvements that fundamentally enhanced its measurement accuracy and generalization performance. Firstly, we remove all the down-sampling operations in the encode module to improve the perception of spatial information, and reduce the number of pyramid levels of the correlation layer to increase the small displacement accuracy. By building the correlation layer to compute the similarity of pixel pairs, and iteratively updating the displacement field through a recurrent unit, RAFT-DIC introduces the prior information of DIC measurement to guide the displacement estimation with high accuracy. Secondly, we develop a novel dataset generation method to synthesize customized speckle patterns and diverse displacement fields, which facilitate the construction of a robust and adaptable dataset to improve the network generalization.

Results

Both simulated and real experimental results demonstrate that the accuracy of the proposed method is approximately an order of magnitude higher than pervious deep learning-based DIC (DL-DIC).

Conclusions

The proposed RAFT-DIC shows higher accuracy as well as stronger practicality and cross-dataset generalization performance over existing DL-DIC methods, and is expected to be a new standard architecture for DL-DIC.

背景作为一种基于图像的全场形变测量光学技术，数字图像相关（DIC）的最终目的是在不需要用户输入的情况下，以全自动的方式实现准确、精确和像素级的位移/应变测量：RAFT-DIC基于最先进的光流架构：递归全对场变换（RAFT）。我们进行了两项有针对性的改进，从根本上提高了测量精度和泛化性能。首先，我们取消了编码模块中的所有下采样操作，以提高空间信息的感知能力；同时减少了相关层的金字塔层数，以提高小位移精度。通过建立相关层来计算像素对的相似度，并通过递归单元迭代更新位移场，RAFT-DIC 引入了 DIC 测量的先验信息来指导高精度的位移估计。其次，我们开发了一种新颖的数据集生成方法，以合成定制的斑点模式和多样化的位移场，从而有助于构建稳健且适应性强的数据集，提高网络的泛化能力。结论与现有的 DL-DIC 方法相比，所提出的 RAFT-DIC 具有更高的精度、更强的实用性和跨数据集泛化性能，有望成为 DL-DIC 的新标准架构。

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引用次数: 0

Research on the Mechanical Properties of Single-Lap Rivet-Bonded Hybrid Joint Considering the Rivet Forming Process 考虑铆钉成型工艺的单圈铆接混合接头力学性能研究

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-06-26 DOI: 10.1007/s11340-024-01093-7

X. Han, L. Z. Ren, X. Xu, L. Ying, C. W. Wu, W. B. Hou

Background

This paper investigates the mechanical properties and failure behaviours of rivet-bonded hybrid joints composed of aluminium adherends and steel rivets under quasi-static tensile loading.

Objective

The damage law of hybrid joints is studied to provide a reference for the design and manufacture of hybrid joints.

Methods

Tensile tests were conducted on aluminium and steel specimens at various triaxial stress levels. The corresponding finite element model (FEM) was developed to verify the Johnson–Cook damage parameters of the studied metals. The hybrid joint considering the rivet forming process was constructed through FE modelling using the Johnson–Cook failure criterion and Cohesive Zone Model (CZM), which was then validated with the experimental results.

Results

Experimental results of the hybrid joint showed that a typical two-stage failure: 1) the adhesive layer bears the majority of the load during the initial loading stage, and 2) the adhesive layer completely fails after reaching the peak load and the rivet solely bears the load subsequently.

Conclusions

The riveting process did not cause damage to the adhesive layer, which ensured the reliability of the manufacturing techniques of the hybrid joint. And the yielding of rivets may buffer the immediate failure of hybrid joints.

背景本文研究了由铝粘合剂和钢铆钉组成的铆接混合接头在准静态拉伸载荷下的机械性能和破坏行为。目的研究混合接头的破坏规律，为混合接头的设计和制造提供参考。开发了相应的有限元模型（FEM），以验证所研究金属的约翰逊-库克损伤参数。通过使用约翰逊-库克破坏准则和内聚区模型（CZM）进行有限元建模，构建了考虑铆钉成型过程的混合接头，并与实验结果进行了验证。结果混合接头的实验结果表明，典型的两阶段失效：1）在初始加载阶段，粘合剂层承受了大部分载荷；2）在达到峰值载荷后，粘合剂层完全失效，铆钉独自承受随后的载荷。铆钉的屈服可缓冲混合接头的直接失效。

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引用次数: 0

Operando Characterizations of Lithium Penetration-Induced Fracture in Solid Electrolytes 固体电解质中锂离子穿透诱发断裂的操作特性分析

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-06-26 DOI: 10.1007/s11340-024-01085-7

M. Lu, S. Xia

Background

Lithium penetration-induced fracture within solid electrolytes (SEs) is a major issue hindering the commercialization of solid-state lithium-ion batteries (SS-LIBs). Such fracture has been frequently observed during electrochemical plating of lithium (Li)-metal anodes, but its mechanistic origin is still largely unclear.

Objective

We present the first quantitative operando analysis of the fracture characteristics of a model SE material under battery-relevant electrochemical cycling conditions.

Methods

Full-field deformation during Li deposition-induced cracking of garnet-type LLZTO was measured using the digital image correlation (DIC) method. The obtained displacement data were denoised via equilibrium smoothing, and then fitted to the linear elastic asymptotic crack-tip field to extract the electrochemical fracture toughness values under different current densities.

Results

The physics-based equilibrium smoothing method demonstrated effectiveness in enhancing the accuracy of DIC measurements. The electrochemical fracture toughness obtained was substantially lower than the mechanical fracture toughness of the same material determined through indentation, attributed to combined effects of electrochemical embrittlement and a transition in fracture mode from intergranular to transgranular.

Conclusion

The discrepancy between the two types of fracture toughness suggests that electrochemical cycling could have a significant impact on the fracture mode and resistance of a solid electrolyte.

背景固态电解质（SE）中锂渗透引起的断裂是阻碍固态锂离子电池（SS-LIB）商业化的一个主要问题。在锂（Li）金属阳极的电化学电镀过程中，经常会观察到这种断裂，但其机理起源在很大程度上仍不清楚。通过平衡平滑法对获得的位移数据进行去噪处理，然后与线性弹性渐近裂纹尖端场进行拟合，以提取不同电流密度下的电化学断裂韧性值。获得的电化学断裂韧性大大低于通过压痕法测定的同种材料的机械断裂韧性，这归因于电化学脆化和断裂模式从晶间过渡到晶间的综合影响。

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引用次数: 0

Effect of Speckle Edge Characteristics on DIC Calculation Error 斑点边缘特性对 DIC 计算误差的影响

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-06-07 DOI: 10.1007/s11340-024-01078-6

H. Cui, Z. Zeng, H. Zhang, F. Yang

Background

In DIC studies, positional parameters and speckle size are commonly used to characterise speckle images. The influence of edge parameters is ignored. This leads to a great difference between the DIC calculation results of simulated and real images. And some contradictory results are also produced.

Objective

The main objective of this paper is to investigate the effect of edge parameters. As well as to give more reasonable parameters to describe the speckle characteristics.

Methods

Firstly, this paper proposes a series of more reasonable parameters to describe the speckle features based on the mathematical expression of the speckle image. Subsequently, the effect of different edge functions on the computational error of DIC is investigated. The effect of different edge functions on pre-filtering is also investigated. Finally, real speckle images are produced using Gaussian and step functions to study the difference between the simulated and real speckle images.

Results

Generally, it is believed that prefiltering can reduce the computational error of DIC, but for Gaussian edges, prefiltering hardly reduces the error, whereas hybrid edges correctly exhibit this phenomenon. Although the Gaussian edge perform well in the simulation, the actual speckle images taken show that the DIC error corresponding to the camera-acquired Gaussian speckle is much larger than that of the step speckle.

Conclusions

The introduction of edge parameters to describe speckle images is necessary for DIC studies. Pre-filtering always reduces the DIC error, but for Gaussian edges this property cannot be demonstrated. The most suitable edges in reality are step edges, not Gaussian edges.

背景在 DIC 研究中，位置参数和斑点大小通常用于描述斑点图像的特征。而边缘参数的影响却被忽略了。这就导致了模拟图像和真实图像的 DIC 计算结果之间存在很大差异，并产生了一些相互矛盾的结果。本文的主要目的是研究边缘参数的影响。方法首先，本文根据斑点图像的数学表达式，提出了一系列更合理的参数来描述斑点特征。随后，研究了不同边缘函数对 DIC 计算误差的影响。还研究了不同边缘函数对预滤波的影响。结果一般认为，预过滤可以减少 DIC 的计算误差，但对于高斯边缘，预过滤几乎不能减少误差，而混合边缘却能正确显示这一现象。虽然高斯边缘在模拟中表现良好，但实际拍摄的斑点图像显示，相机获取的高斯斑点对应的 DIC 误差远远大于阶跃斑点。预滤波总能减少 DIC 误差，但对于高斯边缘，这一特性却无法体现。现实中最合适的边缘是阶梯边缘，而不是高斯边缘。

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引用次数: 0

Stereo-DIC Challenge 1.0 – Rigid Body Motion of a Complex Shape Stereo-DIC Challenge 1.0 - 复杂形状的刚体运动

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-05-31 DOI: 10.1007/s11340-024-01077-7

W. Ahmad, J. Helm, S. Bossuyt, P. Reu, D. Turner, L.K. Luan, P. Lava, T. Siebert, M. Simonsen

Background

Stereo-DIC is a widely used optical measurement technique that provides a dense full-field 3D measurement of the shape, displacement, and strain of a solid sample. When compared with 2D-DIC, Stereo-DIC provides greater flexibility and expands its use beyond flat, planar specimens. Furthermore, the widespread availability of commercial systems has led to the adoption of the technique throughout industry, academia, and government research labs.

Objective

Even though some research has been done to understand the effects of different experimental and stereo-DIC parameters, no reference is available to benchmark and compare the performance of current stereo-DIC algorithms to each other.

Methods

This paper provides the description and analysis of a carefully controlled 3D experiment and associated images used to compare the results from five subset based DIC software packages. Both the images and analysis codes used in this paper to compare the results are described here and are available for download and use for continued research.

Results

We show that over a very large range of motion, the 3D errors are very small, less than 80(mu)m over a travel of ±20 mm out-of-plane and ±20 mm in-plane. While all codes performed similarly, there are important differences noted in the paper.

Conclusion

The image sets and results comparison software are hosted by the International DIC Society (www.iDICs.org) and are freely available for download and analysis for comparison with results in this paper. Furthermore, it is hoped that this set of images can be used for future research in improving stereo-DIC by future authors.

背景立体-DIC 是一种广泛使用的光学测量技术，可对固体样品的形状、位移和应变进行密集的全场三维测量。与 2D-DIC 相比，立体-DIC 提供了更大的灵活性，并将其应用扩展到平面试样之外。此外，商业系统的普及也促使该技术在工业界、学术界和政府研究实验室得到广泛应用。方法本文描述并分析了一个精心控制的三维实验和相关图像，用于比较基于子集的五个 DIC 软件包的结果。结果我们发现，在很大的运动范围内，三维误差非常小，在平面外±20 毫米和平面内±20 毫米的行程中，误差小于 80 （mu）米。虽然所有代码的性能相似，但本文中指出了一些重要的差异。结论图像集和结果比较软件由国际 DIC 协会 (www.iDICs.org) 托管，可免费下载和分析，以便与本文中的结果进行比较。此外，我们还希望这组图像可用于未来作者改进立体 DIC 的研究。

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引用次数: 0

Optimizing Pure Shear Experiment to Properly Characterize the Shear Properties of Thin-Walled Aluminum Alloy Tubes 优化纯剪切实验，正确表征薄壁铝合金管的剪切特性

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-05-30 DOI: 10.1007/s11340-024-01080-y

S. Zhang, X. Wang, W. Hu, G. Liu

Background

For an anisotropic thin-walled tube without changing its circular geometry, only the experimental data of initial yield and subsequent plastic deformation along the axial and circumferential directions can be obtained till now. These experimental data are not sufficient to construct an anisotropic constitutive relation for simulations of tube deformation processes.

Objective

A novel shear test of tubular materials is proposed to achieve the state of shearing plastic deformation along the axial direction of thin-walled tubes.

Methods

Two semi-circle mandrels and one specially designed tubular specimen are used in the shear experiment. Optimizations of the specimen shape and mandrel structure were carried out by using FE simulation. The influence of the specimen shape, such as the length of the shear zone and the length of the axial slot, on the stress state of the shear zone was discussed. A thin-walled 5052 aluminum tube was used in the shear experiment using the optimized specimen shape. To understand the corresponding relationship between the tensile properties and the shear properties of an anisotropic tube, the uniaxial tension stress-strain relationship was equivalently transformed to the shear stress-stain relationship using the Mises, Tresca, Hill48, and Barlat-lian constitutive functions.

Results

After optimizing the specimen shape, the shearing condition of the tested tube is closer to the pure shear stress state. Based on the tests, the pure shear stress state can be maintained to a large deformation extent. The experimental shear stress-strain relationship was compared with the converted stress-strain relationship based on the uniaxial tension tests using the Mises, Tresca, Hill48, and Barlat-lian constitutive functions. The results show a large difference between the transformed stress-strain relationship and the shear stress-strain relationship.

Conclusions

This testing method can provide necessary empirical data with the principal stress directions along the direction at an angle of 45° to the tube axis. The shear plastic deformation properties of some anisotropic materials cannot be equivalently described by the experimental data of the tensile test. The shearing characteristics obtained by this novel experimental method can be applied to the characterizations of anisotropic constitutive relations for simulations of tube deformation processes.

背景对于不改变圆形几何形状的各向异性薄壁管材，目前只能获得初始屈服和随后沿轴向和圆周方向塑性变形的实验数据。这些实验数据不足以构建用于模拟管材变形过程的各向异性构成关系。方法在剪切实验中使用了两个半圆心轴和一个特殊设计的管状试样。通过有限元模拟对试样形状和心轴结构进行了优化。讨论了剪切区长度和轴向槽长度等试样形状对剪切区应力状态的影响。在剪切实验中使用了薄壁 5052 铝管，并使用了优化后的试样形状。为了了解各向异性管材的拉伸性能和剪切性能之间的对应关系，使用 Mises、Tresca、Hill48 和 Barlat-lian 构成函数将单轴拉伸应力-应变关系等效转换为剪切应力-应变关系。根据试验结果，纯剪应力状态可以维持到较大的变形程度。使用 Mises、Tresca、Hill48 和 Barlat-lian 构成函数，将实验剪应力-应变关系与基于单轴拉伸试验的换算应力-应变关系进行了比较。结果表明，转换后的应力-应变关系与剪切应力-应变关系之间存在很大差异。结论这种测试方法可以提供必要的经验数据，即主应力方向沿与管轴线成 45° 角的方向。某些各向异性材料的剪切塑性变形特性无法用拉伸试验的实验数据等效描述。通过这种新型实验方法获得的剪切特性可用于各向异性构成关系的表征，以模拟管材的变形过程。

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引用次数: 0

Cryogenic Fracture Characterisation of High-Grade Pipeline Steels Using the Dynamic Tensile Tear Test Equipped with a Large-Surface Spray Cooling System 利用配备大型表面喷雾冷却系统的动态拉伸撕裂试验对高等级管道钢进行低温断裂表征

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-05-30 DOI: 10.1007/s11340-024-01082-w

B. Paermentier, S. Cooreman, S. Coppieters, R. Talemi

Background

In contrast to traditional impact-based testing, the Dynamic Tensile Tear Test (DT3) has shown great potential to characterise high-grade pipeline steels as it mimics the in-field pipeline conditions. However, material characterisation using the DT3 method has only been performed at room temperature and lower-shelf characterisation has not yet been investigated.

Objective

This study investigates a solution to perform low-temperature characterisation and analyse dynamic brittle fracture behaviour using the DT3 setup.

Methods

A large-surface spray cooling system using liquid nitrogen was constructed and implemented onto the DT3 system. Cooling performance and temperature uniformity were assessed using thermocouples across a large surface area up to 412 cm² (2 × 206 cm²). Numerical validation was performed through Finite Element (FE) analysis using the Modified Bai-Wierzbicki (MBW) material model. A combined stress–strain criterion was used to take into account cleavage failure.

Results

Temperatures down to -125 °C were reached using the spray cooling system and a fracture tests was performed at -80 °C. The obtained data and resulting fracture surface indicated clear brittle fracture behaviour. An average crack velocity of 152 m/s was measured, which is in the same order of magnitude associated with crack velocities observed in large-scale testing.

Conclusions

The constructed spray cooling system proved to be capable of cooling a large volume down to cryogenic temperatures while achieving acceptable temperature uniformity. Lower-shelf characterisation of X70 grade pipeline steel was achieved using the DT3 method and a good correlation was obtained between numerical data and experimental observations.

背景与传统的冲击试验相比，动态拉伸撕裂试验（DT3）模拟了现场管道条件，因此在表征高等级管道钢方面显示出巨大的潜力。然而，使用 DT3 方法进行的材料表征仅在室温下进行，尚未对低温表征进行研究。本研究调查了使用 DT3 设置进行低温表征和分析动态脆性断裂行为的解决方案。使用热电偶对高达 412 平方厘米（2 × 206 平方厘米）的大表面区域的冷却性能和温度均匀性进行了评估。通过使用改良 Bai-Wierzbicki (MBW) 材料模型进行有限元 (FE) 分析，进行了数值验证。结果使用喷雾冷却系统将温度降至 -125 °C，并在 -80 °C下进行了断裂测试。获得的数据和断裂面显示了明显的脆性断裂行为。测得的平均裂纹速度为 152 米/秒，与大规模测试中观察到的裂纹速度处于同一数量级。使用 DT3 方法实现了 X70 级管线钢的下层表征，并在数值数据和实验观察之间获得了良好的相关性。

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引用次数: 0

A Deep Learning-Driven Fast Scanning Method for Micro-Computed Tomography Experiments on CMCs 用于 CMC 显微计算机断层扫描实验的深度学习驱动型快速扫描方法

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-05-24 DOI: 10.1007/s11340-024-01081-x

R.Q. Zhu, G.H. Niu, Z.L. Qu, P.D. Wang, D.N. Fang

Background

In-situ micro-computed tomography (µCT) technology is an attractive approach to investigate the evolution process of damage inside ceramic matrix composites (CMCs) during high-temperature service. The evolution process is highly time-sensitive under temperature-induced loads, and fast scanning is very necessary for in-situ µCT tests.

Objective

The objective of this work is to provide a fast scanning method for in situ µCT tests on CMCs with complex microstructures by the innovation of a reconstruction algorithm.

Method

To overcome the severe degradation of the reconstructed image quality resulting from sparse CT scans, a deep-learning-based multi-domain sparse reconstruction method was proposed. Three sub-networks including the projection-domain, image-domain, and fusion network were constructed in the multi-domain method to make full use of the information from the projection and image domain.

Results

The proposed deep-learning-based sparse reconstruction method provided satisfactory µCT images on C/SiC composites with acceptable quality. The scanning time was reduced by 6 times. All selected evaluation metrics of the proposed method are higher than those of other single-domain methods and traditional iterative method. The segmentation accuracy of the µCT images obtained by the proposed method can meet the subsequent quantitative analysis. An in-situ tensile test of CMCs is conducted to further evaluate the performance in the practical application of in-situ experiments. The results indicate that the weak and thin micro-cracks can still be effectively retained and recovered. A detailed workflow to implement the method generally is also provided.

Conclusions

Based on the deep-learning-based multi-domain sparse reconstruction method, the process of in-situ µCT tests can be greatly accelerated with little loss of the reconstructed image quality.

背景原位微计算机断层扫描（µCT）技术是研究高温服役期间陶瓷基复合材料（CMC）内部损伤演变过程的一种极具吸引力的方法。为了克服稀疏 CT 扫描导致的重建图像质量严重下降的问题，提出了一种基于深度学习的多域稀疏重建方法。结果基于深度学习的稀疏重建方法为 C/SiC 复合材料提供了令人满意的 µCT 图像，图像质量可以接受。扫描时间缩短了 6 倍。与其他单域方法和传统迭代法相比，所提方法的所有选定评价指标都更高。该方法获得的 µCT 图像的分割精度可以满足后续定量分析的需要。对 CMC 进行了原位拉伸试验，以进一步评估其在原位实验实际应用中的性能。结果表明，薄弱的微裂纹仍能有效保留和恢复。结论基于深度学习的多域稀疏重建方法可以大大加快原位 µCT 试验的进程，而重建图像的质量几乎没有损失。

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引用次数: 0

Characterization on Fracture Toughness of Cermet Coating Coupling Instrumented Indentation and X‑Ray Computed Tomography 将仪器压痕法和 X 射线计算机断层扫描法相结合，表征金属陶瓷涂层的断裂韧性

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2024-05-23 DOI: 10.1007/s11340-024-01075-9

R. Huang, Y. Zheng, S. Luo, H. Bai, P. Wang, Y. Chen, Z. Qu

Background

The surface brittle fracture of cermet coating seriously restricts its application. Accurate evaluation of the fracture toughness of cermet coating is a prerequisite for improving its life.

Objective

This paper aims to propose an accurate characterization method for fracture toughness of cermet coating.

Methods

By coupling instrumented indentation and X‑ray computed tomography (XCT), the indentation-induced fracture behaviors under various loads within WC-12%Co coatings were studied. The three-dimensional subsurface crack morphologies and the damage evolution within the coating were nondestructively observed by XCT. The indentation response was correlated with the damage evolution. The impact of substrate effects on indentation-induced fracture behaviors was further studied using finite element analysis (FEA).

Results

The Palmqvist shape of the indentation crack under low loads was successfully identified. The first pop-in event in the load-displacement (P-h) curve was determined to be triggered by bottom cracking, marking the onset of the multiple fracture mode. Laugier’s equation offered a stable and reliable estimation of fracture toughness for the coating in the radial cracking mode.

Conclusions

XCT plays a crucial role in selecting the appropriate equation for indentation toughness calculation. The critical indentation depth for the first pop-in was suggested as the threshold for reliably extracting intrinsic fracture toughness of cermet coatings. Numerical results revealed a constant linear relationship between the critical depth and coating thickness, and a high sensitivity of the critical depth to yield stress of the substrate. The proposed analytical procedure holds potential for generalization to diverse cermet coatings on metal substrates.

背景金属陶瓷涂层的表面脆性断裂严重限制了其应用。本文旨在提出一种精确表征金属陶瓷涂层断裂韧性的方法。方法通过仪器压痕法和 X 射线计算机断层扫描（XCT），研究了 WC-12%Co 涂层在各种载荷下的压痕诱导断裂行为。XCT 对涂层内的三维次表层裂纹形态和损伤演变进行了非破坏性观察。压痕响应与损伤演变相关。利用有限元分析 (FEA) 进一步研究了基底效应对压痕诱导断裂行为的影响。载荷-位移（P-h）曲线中的第一个弹入事件被确定为由底部开裂引发，标志着多重断裂模式的开始。结论 XCT 在选择适当的压痕韧性计算公式方面起着至关重要的作用。建议将首次弹入的临界压痕深度作为可靠提取金属陶瓷涂层内在断裂韧性的临界值。数值结果表明，临界深度与涂层厚度之间存在恒定的线性关系，临界深度对基体屈服应力的敏感性很高。所提出的分析程序有望推广到金属基底上的各种金属陶瓷涂层。

{"title":"Characterization on Fracture Toughness of Cermet Coating Coupling Instrumented Indentation and X‑Ray Computed Tomography","authors":"R. Huang, Y. Zheng, S. Luo, H. Bai, P. Wang, Y. Chen, Z. Qu","doi":"10.1007/s11340-024-01075-9","DOIUrl":"10.1007/s11340-024-01075-9","url":null,"abstract":"<div><h3>Background</h3><p>The surface brittle fracture of cermet coating seriously restricts its application. Accurate evaluation of the fracture toughness of cermet coating is a prerequisite for improving its life.</p><h3>Objective</h3><p>This paper aims to propose an accurate characterization method for fracture toughness of cermet coating.</p><h3>Methods</h3><p>By coupling instrumented indentation and X‑ray computed tomography (XCT), the indentation-induced fracture behaviors under various loads within WC-12%Co coatings were studied. The three-dimensional subsurface crack morphologies and the damage evolution within the coating were nondestructively observed by XCT. The indentation response was correlated with the damage evolution. The impact of substrate effects on indentation-induced fracture behaviors was further studied using finite element analysis (FEA).</p><h3>Results</h3><p>The Palmqvist shape of the indentation crack under low loads was successfully identified. The first pop-in event in the load-displacement (<i>P</i>-<i>h</i>) curve was determined to be triggered by bottom cracking, marking the onset of the multiple fracture mode. Laugier’s equation offered a stable and reliable estimation of fracture toughness for the coating in the radial cracking mode.</p><h3>Conclusions</h3><p>XCT plays a crucial role in selecting the appropriate equation for indentation toughness calculation. The critical indentation depth for the first pop-in was suggested as the threshold for reliably extracting intrinsic fracture toughness of cermet coatings. Numerical results revealed a constant linear relationship between the critical depth and coating thickness, and a high sensitivity of the critical depth to yield stress of the substrate. The proposed analytical procedure holds potential for generalization to diverse cermet coatings on metal substrates.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 7","pages":"1037 - 1051"},"PeriodicalIF":2.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141103656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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