Experimental Mechanics最新文献

{"title":"Thermal Stress Analysis for Functionally Graded Plates with Modulus Gradation, Part II","authors":"T. Baytak,&nbsp;M. Tosun,&nbsp;C. Ipek,&nbsp;C. Mollamahmutoglu,&nbsp;O. Bulut","doi":"10.1007/s11340-024-01091-9","DOIUrl":"10.1007/s11340-024-01091-9","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>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.</p><h3>Methods</h3><p>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 (&gt; 2) step variation of material coefficients in the models.</p><h3>Results</h3><p>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.</p><h3>Conclusions</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 8","pages":"1229 - 1247"},"PeriodicalIF":2.0,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-024-01091-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"User-Independent, Accurate and Pixel-Wise DIC Measurements with a Task-Optimized Neural Network","authors":"B. Pan,&nbsp;Y. Liu","doi":"10.1007/s11340-024-01088-4","DOIUrl":"10.1007/s11340-024-01088-4","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>In this work, we propose a task-optimized neural network, called RAFT-DIC, to achieve user-independent, accurate and pixel-wise displacement field measurements.</p><h3>Methods</h3><p>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.</p><h3>Results</h3><p>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).</p><h3>Conclusions</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 8","pages":"1199 - 1213"},"PeriodicalIF":2.0,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521303","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}

{"title":"Research on the Mechanical Properties of Single-Lap Rivet-Bonded Hybrid Joint Considering the Rivet Forming Process","authors":"X. Han,&nbsp;L. Z. Ren,&nbsp;X. Xu,&nbsp;L. Ying,&nbsp;C. W. Wu,&nbsp;W. B. Hou","doi":"10.1007/s11340-024-01093-7","DOIUrl":"10.1007/s11340-024-01093-7","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>The damage law of hybrid joints is studied to provide a reference for the design and manufacture of hybrid joints.</p><h3>Methods</h3><p>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.</p><h3>Results</h3><p>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.</p><h3>Conclusions</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 8","pages":"1215 - 1227"},"PeriodicalIF":2.0,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508849","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}

{"title":"Operando Characterizations of Lithium Penetration-Induced Fracture in Solid Electrolytes","authors":"M. Lu,&nbsp;S. Xia","doi":"10.1007/s11340-024-01085-7","DOIUrl":"10.1007/s11340-024-01085-7","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>We present the first quantitative <i>operando</i> analysis of the fracture characteristics of a model SE material under battery-relevant electrochemical cycling conditions.</p><h3>Methods</h3><p>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.</p><h3>Results</h3><p>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.</p><h3>Conclusion</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 7","pages":"1161 - 1174"},"PeriodicalIF":2.0,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531593","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}

{"title":"Effect of Speckle Edge Characteristics on DIC Calculation Error","authors":"H. Cui,&nbsp;Z. Zeng,&nbsp;H. Zhang,&nbsp;F. Yang","doi":"10.1007/s11340-024-01078-6","DOIUrl":"10.1007/s11340-024-01078-6","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>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.</p><h3>Methods</h3><p>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.</p><h3>Results</h3><p>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.</p><h3>Conclusions</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 7","pages":"1143 - 1160"},"PeriodicalIF":2.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141371571","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}

{"title":"Stereo-DIC Challenge 1.0 – Rigid Body Motion of a Complex Shape","authors":"W. Ahmad,&nbsp;J. Helm,&nbsp;S. Bossuyt,&nbsp;P. Reu,&nbsp;D. Turner,&nbsp;L.K. Luan,&nbsp;P. Lava,&nbsp;T. Siebert,&nbsp;M. Simonsen","doi":"10.1007/s11340-024-01077-7","DOIUrl":"10.1007/s11340-024-01077-7","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>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.</p><h3>Methods</h3><p>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.</p><h3>Results</h3><p>We show that over a very large range of motion, the 3D errors are very small, less than 80<span>(mu)</span>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.</p><h3>Conclusion</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 7","pages":"1073 - 1106"},"PeriodicalIF":2.0,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-024-01077-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141191279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing Pure Shear Experiment to Properly Characterize the Shear Properties of Thin-Walled Aluminum Alloy Tubes","authors":"S. Zhang,&nbsp;X. Wang,&nbsp;W. Hu,&nbsp;G. Liu","doi":"10.1007/s11340-024-01080-y","DOIUrl":"10.1007/s11340-024-01080-y","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>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.</p><h3>Methods</h3><p>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.</p><h3>Results</h3><p>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.</p><h3>Conclusions</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 7","pages":"1107 - 1121"},"PeriodicalIF":2.0,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141191983","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}

{"title":"Cryogenic Fracture Characterisation of High-Grade Pipeline Steels Using the Dynamic Tensile Tear Test Equipped with a Large-Surface Spray Cooling System","authors":"B. Paermentier,&nbsp;S. Cooreman,&nbsp;S. Coppieters,&nbsp;R. Talemi","doi":"10.1007/s11340-024-01082-w","DOIUrl":"10.1007/s11340-024-01082-w","url":null,"abstract":"<div><h3>Background</h3><p>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.</p><h3>Objective</h3><p>This study investigates a solution to perform low-temperature characterisation and analyse dynamic brittle fracture behaviour using the DT3 setup.</p><h3>Methods</h3><p>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.</p><h3>Results</h3><p>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.</p><h3>Conclusions</h3><p>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.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 7","pages":"1123 - 1142"},"PeriodicalIF":2.0,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141191317","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}

{"title":"A Deep Learning-Driven Fast Scanning Method for Micro-Computed Tomography Experiments on CMCs","authors":"R.Q. Zhu,&nbsp;G.H. Niu,&nbsp;Z.L. Qu,&nbsp;P.D. Wang,&nbsp;D.N. Fang","doi":"10.1007/s11340-024-01081-x","DOIUrl":"10.1007/s11340-024-01081-x","url":null,"abstract":"<div><h3>Background</h3><p><i>In-situ</i> 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 <i>in-situ</i> µCT tests.</p><h3>Objective</h3><p>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.</p><h3>Method</h3><p>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.</p><h3>Results</h3><p>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 <i>in-situ</i> tensile test of CMCs is conducted to further evaluate the performance in the practical application of <i>in-situ</i> 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.</p><h3>Conclusions</h3><p>Based on the deep-learning-based multi-domain sparse reconstruction method, the process of <i>in-situ</i> µCT tests can be greatly accelerated with little loss of the reconstructed image quality.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 7","pages":"1053 - 1072"},"PeriodicalIF":2.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141098652","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}

{"title":"Characterization on Fracture Toughness of Cermet Coating Coupling Instrumented Indentation and X‑Ray Computed Tomography","authors":"R. Huang,&nbsp;Y. Zheng,&nbsp;S. Luo,&nbsp;H. Bai,&nbsp;P. Wang,&nbsp;Y. Chen,&nbsp;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}