Experimental Mechanics最新文献

{"title":"Review: High Speed Temperature Measurements Under Dynamic Loading","authors":"G. G. Goviazin,&nbsp;J. C. Nieto-Fuentes,&nbsp;D. Rittel","doi":"10.1007/s11340-023-01027-9","DOIUrl":"10.1007/s11340-023-01027-9","url":null,"abstract":"<div><h3>Background</h3><p>This review discusses high-speed thermal measurements and their significance in understanding solid materials' behavior, focusing on rapid loading conditions. </p><h3>Objective</h3><p>While high-speed thermal measurements are challenging in some cases, these measurements provide unique insights into material response at high rates, by shedding light on failure modes, thermomechanical coupling, and thermal dissipation phenomena that are otherwise overlooked.</p><h3>Methods</h3><p>The review presents various direct measurement techniques (contact and non-contact) relevant to high-speed loading, with emphasis on the frequently used ones in mechanics of materials applications: thermocouples, infrared detectors, and high-speed infrared cameras. </p><h3>Results</h3><p>Pros and cons of each technique, alongside with typical applications are discussed. Understanding the interplay between thermal effects and mechanical responses opens new avenues for enhancing material performance and energy efficiency.</p><h3>Conclusions</h3><p>This review is expected to serve as a valuable resource for researchers and practitioners seeking to leverage high-speed thermal measurements to drive innovation and advance materials science in various applications.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 3","pages":"295 - 304"},"PeriodicalIF":2.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139556434","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 Label-Free Measurement Method for Plane Stress States in Optical Isotropic Films with Spectroscopic Ellipsometry","authors":"X. Sun,&nbsp;S. Wang,&nbsp;W. Xing,&nbsp;X. Cheng,&nbsp;L. Li,&nbsp;C. Li,&nbsp;Z. Wang","doi":"10.1007/s11340-023-01026-w","DOIUrl":"10.1007/s11340-023-01026-w","url":null,"abstract":"<div><h3>Background</h3><p>Stress measurement for thin films is crucial in a variety of fields such as in semiconductor manufacturing, the optoelectronics industry, and biomedical science, among others. However, most measurement methods require surface treatment of the thin film.</p><h3>Objective</h3><p>A label-free measurement method for plane stress states in optical isotropic thin films based on spectroscopic ellipsometry analysis is proposed and verified in this paper.</p><h3>Methods</h3><p>The proposed method is based on the modulation of the stress-optic effect on reflected spectroscopic ellipsometry. A theoretical model is established to describe the relation between all components of the plane-stress state and the classic ellipsometric parameters (Ψ, Δ). An algorithm is developed to determine all components of a plane-stress state by fitting the model to the experiment data.</p><h3>Results</h3><p>In the verification experiment, we determined the plane stress state of a Cu film coated on a PI (polyimide) substrate. The results show a reasonable agreement between the experimental measurements from spectroscopic ellipsometry and the theoretical analysis based on the applied loading.</p><h3>Conclusion</h3><p>The results prove that our method can effectively measure the plane stress state of optical isotropic thin films.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 3","pages":"341 - 352"},"PeriodicalIF":2.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139556514","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":"Correction: Experimental Investigation of the Ballistic Response of Head Surrogate Against Fragment Simulating Projectiles","authors":"P. K. Pandey,&nbsp;Y. K. Joshi,&nbsp;M. K. Khan,&nbsp;M. A. Iqbal,&nbsp;S. G. Ganpule","doi":"10.1007/s11340-023-01024-y","DOIUrl":"10.1007/s11340-023-01024-y","url":null,"abstract":"","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 2","pages":"291 - 292"},"PeriodicalIF":2.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138818955","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":"On the Cover: Novel Speckle Preparation and Heat Insulation Method for DIC Strain Measurement at Cryogenic Temperature and Large Deformation Environment","authors":"","doi":"10.1007/s11340-023-01025-x","DOIUrl":"10.1007/s11340-023-01025-x","url":null,"abstract":"","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 1","pages":"1 - 1"},"PeriodicalIF":2.0,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138744881","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":"Theoretical Prediction and Experimental Measurement of the Evolution of Polymerization Shrinkage Stress Under Different Photocuring Protocols","authors":"K. Wang,&nbsp;Z.Z. Wang","doi":"10.1007/s11340-023-01019-9","DOIUrl":"10.1007/s11340-023-01019-9","url":null,"abstract":"<div><h3>Background</h3><p>The service quality and life of photopolymerized materials are dramatically impaired by shrinkage stress generated during the polymerization process. Several soft-start photocuring protocols including two-step, ramp, and pulse delay have been proposed to reduce the shrinkage stress. However, the mechanism for the shrinkage stress reduction by soft-start photocuring remains largely elusive.</p><h3>Objective</h3><p>This study aims to explore the mechanism for shrinkage stress reduction in soft-start photocuring protocols and then propose a universal strategy to maximize the stress reduction.</p><h3>Method</h3><p>A theory-experiment-combined method was developed to investigate the effect of soft-start photocuring protocols on the shrinkage stress evolution. Shrinkage stresses under different protocols were measured by a standardized cantilever beam-based instrument. An improved theoretical model incorporating the evolutions of the reaction kinetics and material properties was developed to predict the shrinkage stress evolution under different curing protocols.</p><h3>Results</h3><p>Compared to the standard protocol with a constant photo-irradiation, all the soft-start photocuring protocols could effectively reduce the shrinkage stress and the two-step protocol achieved a maximum reduction of 25% among all experimental conditions. The elastic modulus of photopolymers coincided under the same radiant exposure and irradiation intensity. Unlike previous studies focusing on the mechanical properties of the photopolymers, we found that the shrinkage stress reduction by soft-start photocuring protocols could be attributed to a delayed gelation and a reduction in the peak temperature change after gelation. Based on these mechanisms, adding a delay time before the gelation was proposed as an effective strategy to reduce the shrinkage stress, leading to a reduction of up to more than 40% according to the theoretical predictions. Additionally, the timing for introducing the delay and its duration can be effectively and conveniently determined by monitoring the real-time evolution of shrinkage stress in the standard photocuring protocol.</p><h3>Conclusions</h3><p>This theory-experiment-combined study not only uncovers that the shrinkage stress reduction by soft-start photocuring protocol is attributed to the delay in the gelation and the reduction of the peak temperature change after the gelation but also proposes an effective approach to mitigate shrinkage stress by adding a delay time before the gelation. Such a strategy for maximizing the shrinkage stress reduction while maintaining the mechanical and curing properties is to guide the practical applications of photopolymers.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 2","pages":"225 - 244"},"PeriodicalIF":2.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138632150","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":"Quantitative Evaluation of Interfacial Defect Size and Pattern by Solving a 3D Inverse Problem Based on Step Heating Thermography","authors":"L. Zhuo,&nbsp;Y. Xu,&nbsp;J. Zhu,&nbsp;C. Li,&nbsp;C. Liu,&nbsp;F. Yi","doi":"10.1007/s11340-023-01021-1","DOIUrl":"10.1007/s11340-023-01021-1","url":null,"abstract":"<div><h3>Background</h3><p>Active infrared thermography is proved to be viable and attractive for non-destructive evaluation of interfacial defects like delaminations in a coating-substrate system. But it is a challenging task to accurately quantify small and deeply buried defects from thermal images, due to the inevitable effects of lateral heat diffusion and measurement noise.</p><h3>Objective</h3><p>The aim of this work is to estimate the size and pattern of defects at the interface of a two-layer system with high accuracy and high reliability based on step heating thermography.</p><h3>Methods</h3><p>To characterize the effect of defect on the heat flow, a virtual heat flux is assumed at the interface, which is reconstructed from measured surface temperature by solving a three-dimensional inverse problem. The inverse solution is obtained using the Green’s function and regularization techniques, and then used for estimating the defect pattern by threshold segmentation. An improvement on computational efficiency is achieved by an iteratively substitution of nodal temperature.</p><h3>Results</h3><p>Simulations with synthetic data generated by a finite element model validate the feasibility of this approach. Results obtained from experiments for an Aluminum oxide/steel system show the robustness of this approach, when temperatures are contaminated with measurement noise. Both the performance on estimation of various defect shapes and the effects of regularization are discussed.</p><h3>Conclusion</h3><p>This study show that the present approach brings an improvement in accuracy and reliability for the estimation of size and pattern of defects with various diameter-to-depth ratios, in comparison with conventional techniques.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 2","pages":"245 - 259"},"PeriodicalIF":2.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138632068","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":"Assessing the Validity of Analytical Equations for Offshore Power Cable Bending with Fixed and Loose Tube Fiber Strain Sensors","authors":"J. Ryvers,&nbsp;M. Loccufier,&nbsp;W. De Waele","doi":"10.1007/s11340-023-01023-z","DOIUrl":"10.1007/s11340-023-01023-z","url":null,"abstract":"<div><h3>Background</h3><p>Subsea power cable failures in offshore wind farms result in significant financial losses. One common failure mode is submarine power cable bending.</p><h3>Objective</h3><p>The primary objective of this study is to validate two analytical models using strain readings obtained from a novel 3-point bending setup designed for power cable specimens. The setup incorporates two types of optical fiber sensors for simultaneous strain measurement.</p><h3>Methods</h3><p>A 3-point bending setup is constructed, integrating optical fiber sensors installed on the embedded fiber optic cable within the submarine power cable. One set of sensors is fixed to the fiber optic cable sheath, while a second set consists of loose tube fibers that are inside the fiber optic cable. The strain readings of the fixed sensors are compared to two analytical models. The first analytical model assumes a constant power cable curvature, while the second model considers variable curvature.</p><h3>Results</h3><p>The analytical models both predict nearly flat strain profiles and are in line with each other. The strain data, however, approaches zero strain away from the cable center. Model assumptions such as perfect sensor positioning and zero slip of the fiber optic cable cause this discrepancy. The results of the constant curvature model agree well with strain averages of the fixed sensors around the central region of the power cable, and both scale linearly with amplitude. Finally, the strain readings from the loose tube fibers demonstrate high reproducibility, facilitating the development of a calibration curve for estimating power cable curvature.</p><h3>Conclusions</h3><p>The analytical models surpass existing models by providing good agreement with the measured strain around the cable center. Moreover, the highly reproducible strain readings from the loose tube fibers allow estimating power cable curvature.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 2","pages":"211 - 223"},"PeriodicalIF":2.0,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138561556","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":"Mitigating Oblique Impacts by Unraveling of Buckled Carbon Nanotubes in Helmet Liners","authors":"B. Maheswaran,&nbsp;K. Chawla,&nbsp;R. Thevamaran","doi":"10.1007/s11340-023-01013-1","DOIUrl":"10.1007/s11340-023-01013-1","url":null,"abstract":"<div><h3>Background</h3><p>Helmet systems most commonly experience oblique blunt impacts which cause simultaneous linear and rotational accelerations. The ability to attenuate both linear and rotational accelerations by absorbing the normal shock while accommodating large shear deformations with energy dissipation is critical to developing superior helmet liners that prevent traumatic brain injury (TBI).</p><h3>Objective</h3><p>To investigate the quasistatic compression-shear response of vertically aligned carbon nanotube (VACNT) foams—which are known for their exceptional specific energy absorption in compression—and explore their potential of accommodating large shear strains at lower shear stress levels, under large compression-shear loadings.</p><h3>Methodology</h3><p>We investigate the quasistatic compression shear response of freestanding vertically aligned carbon nanotube foams subjected to varied initial precompressions. We use <i>in situ</i> high speed microscopy to visualize the microscale deformations during shear.</p><h3>Results</h3><p>Vertically aligned carbon nanotube foams exhibit a nonlinear hysteric shear stress–strain response that varies as a function of initial normal precompression. At a given precompression, initial linear response at very low shear strains leads to a behavior showing increasing compliance leading to a plateau like regime at moderate shear strains and then transitions into a stiffening behavior at high shear strains. The shear stress–strain response softens with the increase in initial precompression demonstrating the vertically aligned carbon nanotube foam’s potential to accommodate large shear strains more effectively at severe compression-shear loads unlike other solids that typically jam. <i>In situ</i> high-speed microscopy reveals the unraveling of carbon nanotubes that collectively buckled during precompression, allowing them to accommodate large shear strains at low shear stress levels.</p><h3>Conclusion</h3><p>We demonstrate the ability of vertically aligned carbon nanotube to accommodate large shear strains at lower shear stress levels under large compression-shear loadings. We propose a model to predict the compression-shear response at different precompressive strains and use this model to develop a deformation modality diagram that categorizes the dominant deformation mechanisms at different loads along different loading angles.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 2","pages":"197 - 209"},"PeriodicalIF":2.0,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138561521","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":"Residual Stresses in Alloy IN718 Produced Through Modulated Laser Powder Bed Fusion","authors":"K. Georgilas,&nbsp;H. Guo,&nbsp;B. Ahmad,&nbsp;R. H. U. Khan,&nbsp;M. E. Fitzpatrick,&nbsp;M. E. Kartal","doi":"10.1007/s11340-023-01018-w","DOIUrl":"10.1007/s11340-023-01018-w","url":null,"abstract":"<div><h3>Background</h3><p>Laser powder bed fusion (L-PBF) additive manufacturing (AM) is used for building metallic parts layer-by-layer and often generates non-uniform thermal gradients between layers during fabrication, resulting in the development of residual stresses when parts are cooled down.</p><h3>Objective</h3><p>The impact of modulated laser used during the L-PBF process on residual stresses in Inconel 718 (IN718) material was investigated. The impact of build directions on residual stress is also determined.</p><h3>Methods</h3><p>The contour method is employed to measure the full-field residual stress component on the cross-section of samples. A complementary residual stress measurement method, incremental hole drilling, was employed for obtaining in-plane residual stress components.</p><h3>Results</h3><p>The results show that the residual stress distribution is sensitive to the build direction, with a higher magnitude of residual stress in the direction of build than that in the transverse direction. Multiple measurements with the same manufacturing parameters show good repeatability.</p><h3>Conclusion</h3><p>Residual stresses in the as-built parts are significant and hence a further consideration regarding relieving residual stresses is required when post-thermal treatments are developed.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 2","pages":"181 - 195"},"PeriodicalIF":2.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-023-01018-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138547597","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":"A Thermodynamic Framework for Rapid Prediction of S-N Curves Using Temperature Rise at Steady-State","authors":"A. Mahmoudi,&nbsp;M.M. Khonsari","doi":"10.1007/s11340-023-01016-y","DOIUrl":"10.1007/s11340-023-01016-y","url":null,"abstract":"<div><h3>Background</h3><p>Building S-N curves for materials traditionally involves conducting numerous fatigue tests, resulting in a time-consuming and expensive experimental procedure that can span several weeks. Thus, there is a need for a more efficient approach to extract the S-N curves.</p><h3>Objective</h3><p>The primary purpose of this research is to propose a reliable approach in the framework of thermodynamics for the rapid prediction of fatigue failure at different stress levels. The proposed method aims to offer a simple and efficient means of extracting the S-N curve of a material.</p><h3>Methods</h3><p>In this paper, a method is introduced based on the principles of thermodynamics. It uses the fracture fatigue entropy (FFE) threshold to estimate the fatigue life by conducting a limited number of cycles at each stress level and measuring the temperature rise during the steady-state stage of fatigue.</p><h3>Results</h3><p>An extensive set of experimental results with carbon steel 1018 and SS 316 are conducted to illustrate the utility of the approach. Also, the efficacy of the approach in characterizing the fatigue in axial and bending loadings of SAE 1045 and SS304 specimens is presented. It successfully predicts fatigue life and creates the S-N curves.</p><h3>Conclusion</h3><p>The effectiveness of the approach is evaluated successfully for different materials under different loading types. The results show that the temperature rise is an indicator of the severity of fatigue and can be used to predict life.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"64 2","pages":"167 - 180"},"PeriodicalIF":2.0,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138507491","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}