{"title":"An Inverse Parameter Identification in Finite Element Problems Using Machine Learning-Aided Optimization Framework","authors":"A. Tariq, B. Deliktaş","doi":"10.1007/s11340-024-01136-z","DOIUrl":"10.1007/s11340-024-01136-z","url":null,"abstract":"<div><h3>Background</h3><p>The ability of finite element analysis to produce high fidelity results is greatly dependent on quality of constitutive model and the accuracy of their parameters. As such, the calibration of phenomenological constitutive models to replicate real-world behaviors has remained a focal point of many research works.</p><h3>Objective</h3><p>A new inverse identification approach combining numerical-experimental methods and data-driven techniques to characterize the nonlinear response of materials using a single experiment is proposed.</p><h3>Methods</h3><p>This approach integrates finite element analysis, optimization methods and machine learning techniques, such as Artificial Neural Networks and Support Vector Regression, to accurately determine model parameters while significantly reducing computational time. This approach can be used to characterize a wide range of models irrespective of the number of parameters involved. A detailed flowchart of the methodology focusing on its implementation aspects is provided and its each module is explained.</p><h3>Results</h3><p>The proposed model calibration approach successfully identified eight parameters for a cohesive zone model implemented in user element subroutine (UEL), four parameters for a hardening model implemented in user material subroutine (UMAT), and five parameters for a Johnson–Cook plasticity model. In all cases, this method achieved an excellent fit between the simulation and experimental results. Moreover, it demonstrated a significant improvement in efficiency, being 2–3 times faster than traditional optimization algorithms in determining optimal parameters.</p><h3>Conclusions</h3><p>Based on the presented investigations, the proposed machine learning-based inverse method can significantly accelerate the parameter identification procedure and can be extended to a wide range of material models.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 3","pages":"325 - 349"},"PeriodicalIF":2.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554015","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}
H. Sadaghian, S. Khalilzadehtabrizi, S. Khodadoost, J.H. Yeon
{"title":"Torsional Performance of Vat-Photopolymerized Tough Resin: Influence of Gauge Length and UV Post-Curing","authors":"H. Sadaghian, S. Khalilzadehtabrizi, S. Khodadoost, J.H. Yeon","doi":"10.1007/s11340-024-01135-0","DOIUrl":"10.1007/s11340-024-01135-0","url":null,"abstract":"<div><h3>Background</h3><p>A myriad of materials, ranging from soft sensors to bone substitutes, undergo torsional loading throughout their operational lifespan. Many of these materials are produced using additive manufacturing (AM) technology due to its broad applicability. Understanding the torsional behavior of these AM components is crucial prior to their utilization. However, research on the torsional behavior of solid additively-manufactured resin polymers remains very limited.</p><h3>Objective</h3><p>To address the gap in understanding the torsional behavior of additively-manufactured resin polymers, this study aimed to investigate the effect of varying gage lengths and UV post-curing durations on the torsional capacity, shear modulus, and energy absorption characteristics of these materials.</p><h3>Methods</h3><p>Torsion specimens were fabricated using vat photopolymerization (VPP) with <i>AnyCubic</i> UV Tough Resin. The specimens were prepared with different gage lengths (20, 40, 60, and 80 mm) and were subjected to five UV post-curing durations (0, 15, 30, 60, 90, and 120 min). Monotonic torsion was applied to the specimens until failure at a rate of 0.1 revolutions per minute.</p><h3>Results</h3><p>The tests revealed ductile failure patterns across all specimens. Longer post-curing times were found to correlate with increased torsional capacities and shear moduli. However, conclusions regarding energy absorption per unit volume remained inconclusive. The results showed that UV exposure had a significantly greater impact on the mechanical properties of the specimens compared to the gage length. Additionally, a normalized trilinear model was proposed to characterize the behavior of additively-manufactured resin polymers under monotonic torsion, which facilitates numerical simulation of material responses in finite element software.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 3","pages":"365 - 384"},"PeriodicalIF":2.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-024-01135-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554016","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}
R. Kaczmarek, L. Teixeira, M. Mouiya, J.-C. Dupré, P. Doumalin, O. Pop, N. Tessier-Doyen, M. Huger
{"title":"Study of Thermomechanical Behaviour of Refractory Materials Under Thermal Gradient. Part II—Experimental and Numerical Analysis on the Example of a Shaped Alumina Spinel Refractory","authors":"R. Kaczmarek, L. Teixeira, M. Mouiya, J.-C. Dupré, P. Doumalin, O. Pop, N. Tessier-Doyen, M. Huger","doi":"10.1007/s11340-024-01142-1","DOIUrl":"10.1007/s11340-024-01142-1","url":null,"abstract":"<div><h3>Background</h3><p>Improving the understanding of how a refractory material responds to thermal shocks and allowing the validation of finite element models require a valuable tool for experimental data collection.</p><h3>Objective</h3><p>This paper presents a comprehensive thermal shock behaviour analysis of an alumina spinel refractory material using the recently developed device in part I.</p><h3>Methods</h3><p>Based on real material properties evolving with temperature and on characteristics of the applied laser beam sequence, the Finite Element Method transient heat transfer model has been validated through the experimental displacement/strain/temperature fields obtained with the developed device.</p><h3>Results</h3><p>The experimental evolution of strain and temperature fields at the bottom of the sample during the applied thermal shock testing sequence have been found to be similar to those evaluated by FEM modelling. Three-dimensional evolutions of stress state within the sample during the applied laser sequence leads to thermal bowing of the sample which is identified by both experimental measurements and by FEM modelling. An occurrence of a macrocrack has been clearly detected at a specific laser heating cycle using Two-Part Digital Image Correlation technique.</p><h3>Conclusions</h3><p>The innovative approach, presented in these two linked articles, offers a comprehensive understanding of the thermal shock behaviour of a representative refractory material using both numerical simulations and experimental techniques.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 3","pages":"351 - 364"},"PeriodicalIF":2.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554014","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":"Compressive Properties of Aluminium Foam-Filled Square Stainless Steel Tubes With Elliptical and Circular Holes","authors":"M.M. Su, Q.X. Ma, A. Zhang, H. Wang","doi":"10.1007/s11340-024-01143-0","DOIUrl":"10.1007/s11340-024-01143-0","url":null,"abstract":"<div><h3>Background</h3><p>Achieving stable deformation of lightweight thin-walled structures is the goal of the anti-collision energy field. Tube wall perforation and foam filling provide an effective approach for achieving the goal.</p><h3>Objective</h3><p>The objective of this paper is to realize adjustable mechanical properties and deformation of thin-walled tubes by optimizing the perforation shape and rate, the foam filling rate and the pore arrangement.</p><h3>Methods</h3><p>The effects of the perforation rate of negative Poisson’s ratio elliptical holes, the regular and staggered arrangement of positive Poisson’s ratio circular holes, and the number of foam filling layers on the mechanical response of stainless steel square tubes were experimentally studied. Additionally, samples with different elliptical distribution positions, foam filling rates, tube wall thicknesses, elliptical hole sizes and foam densities were simulated.</p><h3>Results</h3><p>Elliptical holes caused the square tube to exhibit an auxetic effect, while circular holes caused the square tube to protrude outwards. The foam filling alleviated the unstable deformation of the square tubes with circular holes. The distribution of elliptical holes had a great influence on the deformation behaviour. Increasing the thickness of the elliptical hole tube wall and decreasing the thickness of the solid tube wall stabilised the deformation and mechanical properties of the sample. Small elliptical holes and high-density foam can improve the sample properties.</p><h3>Conclusions</h3><p>Through structural design, the mechanical properties and deformation behaviour of thin-walled square tubes can be effectively controlled to meet different application requirements.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 3","pages":"307 - 324"},"PeriodicalIF":2.0,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-024-01143-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553878","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":"Analysis of Deformation Mechanisms in Metal Extrusion of 17–4 PH Stainless Steel: Influence of Layer Thickness and Contour Number","authors":"J. Marae Djouda, M. Ali Bouaziz, F. Hild","doi":"10.1007/s11340-024-01138-x","DOIUrl":"10.1007/s11340-024-01138-x","url":null,"abstract":"<div><h3>Background</h3><p>Metal extrusion additive manufacturing (MEAM) is a cost-effective method for fabricating parts. Understanding the impact of processing parameters and their interactions on mechanical properties remains challenging.</p><h3>Objective</h3><p>This study aims to investigate the relationship between layer thickness, number of contours and the deformation mechanisms of 17–4 PH stainless steel parts produced through Atomic Diffusion Additive Manufacturing (ADAM).</p><h3>Methods</h3><p>Notched samples were fabricated with two different layer thicknesses (50 µm and 125 µm) and two contour configurations (2 and 4 contours). In-situ tensile tests combined with digital image correlation (DIC) were performed to investigate strain fields.</p><h3>Results</h3><p>The results indicate that the layer thickness significantly influences crack propagation, while also interacting with the number of contours. All samples achieved similar notch opening displacements (NOD) at failure. Differences in layer thickness and contour configurations led to distinct deformation mechanisms.</p><h3>Conclusions</h3><p>Variations in layer thickness and number of contours affected the deformation mechanisms and crack propagation in parts manufactured by MEAM, underscoring the importance of optimizing these parameters to enhance the mechanical performance.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 4","pages":"467 - 480"},"PeriodicalIF":2.0,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143919061","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":"Investigating De-Bonding Using an Impact Loaded Blister Test","authors":"S. Devi, V. Parameswaran","doi":"10.1007/s11340-024-01137-y","DOIUrl":"10.1007/s11340-024-01137-y","url":null,"abstract":"<div><h3>Background</h3><p>De-bonding is a commonly observed failure in adhesively bonded system under impact loading. Therefore, it is important to understand such failures for properly designing and evaluating the integrity of these systems.</p><h3>Objective</h3><p>An Impact Loaded Blister Test (ILBT) is proposed to investigate de-bonding under impact loading and to obtain the de-bond initiation toughness. Further the Cohesive Zone (CZ) parameters for de-bonding are also determined.</p><h3>Methods</h3><p>An adhesively bonded steel-Poly Metha Methyl Acrylate (PMMA) system was used for tests. A polycarbonate (PC) loading bar, impacted by another PC bar, was used to load the PMMA layer and initiate growth of an existing de-bond. From the strain history measured at mid-length of the loading bar, the load and load-point displacement histories were calculated. The critical energy release rate at the instant the de-bond starts to grow was calculated through an axisymmetric analysis. Finite element analysis (FEA) with CZ was carried out and the remaining parameters of CZ were obtained by inverse approach.</p><h3>Results</h3><p>High-speed imaging of the de-bonding processes indicated a circular de-bond growing radially outward. Load-point displacement rate as high as 3.5 m/s was achieved. De-bond growth rate of 115 m/s and de-bond area growth rate of 8 m<sup>2</sup>/s were achieved. CZ parameters obtained through inverse approach were able to accurately predict the debonding observed in experiment.</p><h3>Conclusion</h3><p>The ILBT is demonstrated for isotropic material as a promising technique for determining the de-bond toughness and the CZ parameters of adhesively bonded systems under displacement rate comparable to that encountered in impact like situations.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 2","pages":"241 - 253"},"PeriodicalIF":2.0,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513296","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}
Q. Hu, A. Beaurain, J. F. Witz, A. El Bartali, D. Najjar
{"title":"Comparison of Hall–Petch Law with an Elastic Limit Identification Method Using Kinematic Field Measurements","authors":"Q. Hu, A. Beaurain, J. F. Witz, A. El Bartali, D. Najjar","doi":"10.1007/s11340-024-01140-3","DOIUrl":"10.1007/s11340-024-01140-3","url":null,"abstract":"<div><h3>Background</h3><p>Plastic deformation in polycrystalline metals is highly heterogeneous due to the varied microstructure distribution. Although some traditional laws, such as the Hall–Petch law, describe the relationship between microstructure and yield stress, accurately predicting the initial yield stress (hence elastic limit) related to local plasticity activation remains challenging.</p><h3>Objective</h3><p>This study proposes a novel approach to identify local elastic limits using full-field strain measurements, avoiding complex constitutive models.</p><h3>Methods</h3><p>Full-field kinematic measurements were performed on the heat-treated polycrystalline 316L austenitic stainless steel. By examining the different mechanical responses during elastic and plastic deformation, the onset of plasticity activation for each grain is identified from its grain-average strain evolution, allowing further calculation of the grain-scale elastic limit.</p><h3>Results</h3><p>Strain field observations indicate early strain localizations, particularly at twin boundaries and triple junctions. Based on microstructures segmented by ordinary grain and twin boundaries, considering and not considering twins, two different local elastic limits are identified.</p><h3>Conclusions</h3><p>The average elastic limit for the case considering twins is closer to the value obtained from the macroscopic stress–strain curve. In addition, the statistical analysis of the classified grain sizes reveals a more pronounced Hall–Petch relationship when twins are considered. These results indicate the necessity of considering twins in identifying the local mechanical properties.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 2","pages":"205 - 220"},"PeriodicalIF":2.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513343","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}
K.S.O. Li, A. Van Lerberghe, A. D. Barr, A. A. Dennis, S. D. Clarke
{"title":"Split-Hopkinson Pressure Bar Testing of Water with Partial Lateral Confinement","authors":"K.S.O. Li, A. Van Lerberghe, A. D. Barr, A. A. Dennis, S. D. Clarke","doi":"10.1007/s11340-024-01134-1","DOIUrl":"10.1007/s11340-024-01134-1","url":null,"abstract":"<div><h3>Background</h3><p>For the first time, the high-strain-rate behaviour of water is investigated experimentally and validated to LS-DYNA numerical simulations, using Smooth Particle Hydrodynamics (SPH).</p><h3>Objective</h3><p>This paper presents the application of a modified split-Hopkinson pressure bar (SHPB) fitted with a partial lateral confinement apparatus on a water specimen.</p><h3>Method</h3><p>The lateral confinement is provided by a water reservoir surrounding the specimen. A pressure transducer is installed in the reservoir wall to measure lateral stresses, and a dispersion correction algorithm, <span>SHPB_Processing.py</span>, is utilised to obtain accurate measurements of axial and radial stresses and strains.</p><h3>Results</h3><p>Experimental results underscore the capability of the modified apparatus to assess triaxial behaviour of water under high-strain rates. Comparisons with numerical modelling reveal that cohesion between water particles is non-existent, highlighting an intrinsic limitation in numerical modelling.</p><h3>Conclusion</h3><p>These results highlight the capability to perform characterisation of fluids under high-strain rates. While limitations in numerical modelling still exist, numerical modelling and experimental testing using the modified apparatus can be applied to characterise fluid behaviour in the future.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 2","pages":"195 - 203"},"PeriodicalIF":2.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-024-01134-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513337","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":"On the Cover: A Novel Method to In-Situ Characterize Fatigue Crack Growth Behavior of Nickel Based Superalloys by Laser Thermography","authors":"","doi":"10.1007/s11340-024-01132-3","DOIUrl":"10.1007/s11340-024-01132-3","url":null,"abstract":"","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 1","pages":"1 - 1"},"PeriodicalIF":2.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142994517","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":"Physics-Informed Neural Network Based Digital Image Correlation Method","authors":"B. Li, S. Zhou, Q. Ma, S. Ma","doi":"10.1007/s11340-024-01139-w","DOIUrl":"10.1007/s11340-024-01139-w","url":null,"abstract":"<div><h3>Background</h3><p>Deep Learning-based Digital Image Correlation (DL-DIC) approaches take advantages such as pixel-wise calculation in a full-automatic manner without user's input and improved accuracy in non-uniform deformation measurements. However, DL-DIC still faces accuracy limitations due to the lack of high-precision real-world training data in supervised-learning methods and the need for smoothing noisy solutions in unsupervised-learning methods.</p><h3>Objective</h3><p>This paper proposes a DIC solution method based on Physics-Informed Neural Networks (PINN), called PINN-DIC, to address deformation measurement challenges of current DL-DIC in practical applications.</p><h3>Methods</h3><p>PINN-DIC utilizes a fully connected neural network, with regularized spatial coordinate field as input and displacement field as output. It applies the photometric consistency assumption as a physical constraint, using grayscale differences between predicted and actual deformed images to construct a loss function for iterative optimization of the displacement field. Additionally, a warm-up stage is designed to assist in iterative optimization, allowing PINN-DIC to achieve high accuracy in analyzing both uniform and non-uniform displacement fields.</p><h3>Results</h3><p>PINN-DIC, validated through simulations and real experiments, not only maintained the advantages of other DL-DIC methods but also demonstrated superior performance in achieving higher accuracy than conventional unsupervised DIC and handling irregular boundaries with adjusting the input coordinate field.</p><h3>Conclusions</h3><p>PINN-DIC is an unsupervised method that takes a regularized coordinate field (instead of speckle images) as input and achieves higher accuracy in deformation field results with a simple network. It introduces a novel approach to DL-DIC, enhancing performance in complex measurement scenarios.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 2","pages":"221 - 240"},"PeriodicalIF":2.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513336","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}