This contribution deals with the development of a new shear specimen, which allows precise simple shear measurements for large shear values. The main idea is that the shear load for the rubber mat is applied via steel pins. A form fit connection has the advantage that for the load application, no clamping force or high friction coefficient is required. In addition, the disadvantages resulting from vulcanisation or bonding, for example, shrinkage, are avoided. This offers the big advantage that homogeneous ageing tests can be performed, and also fibre‐reinforced materials can be tested. In order to show the potential of the new pin design, simulation results are compared to each other, and also a first experimental implementation is conducted. The new shear specimen can be used for phenomenological investigations of rubber properties, like Payne effect, Mullins effect, anisotropy, permanent set, softening, recovery, creep and relaxation behaviour.
{"title":"Development of a shear device for precise simple shear measurements of rubber mats","authors":"Lars Kanzenbach, J. Ihlemann","doi":"10.1111/str.12376","DOIUrl":"https://doi.org/10.1111/str.12376","url":null,"abstract":"This contribution deals with the development of a new shear specimen, which allows precise simple shear measurements for large shear values. The main idea is that the shear load for the rubber mat is applied via steel pins. A form fit connection has the advantage that for the load application, no clamping force or high friction coefficient is required. In addition, the disadvantages resulting from vulcanisation or bonding, for example, shrinkage, are avoided. This offers the big advantage that homogeneous ageing tests can be performed, and also fibre‐reinforced materials can be tested. In order to show the potential of the new pin design, simulation results are compared to each other, and also a first experimental implementation is conducted. The new shear specimen can be used for phenomenological investigations of rubber properties, like Payne effect, Mullins effect, anisotropy, permanent set, softening, recovery, creep and relaxation behaviour.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2021-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12376","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48359470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information","authors":"","doi":"10.1111/str.12355","DOIUrl":"https://doi.org/10.1111/str.12355","url":null,"abstract":"No abstract is available for this article.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2021-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12355","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42294280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work presents results from oedometric compression of coarse granular material. Coarse granular media exhibit significant deformations making it complicated to predict the settlement of structures. In this paper, a measurement technique was developed for the analysis of two‐dimensional (2‐D) images of a deforming coarse granular medium to investigate its deformation. This was achieved by realising grain‐based image correlation to measure the grain transformation in gravel with the use of a digital image correlation technique. The 2‐D displacement fields enable us to explore the behaviour of granular media at different scales: microscopic, mesoscopic and macroscopic scales. The mesoscopic scale is defined from branches that connect the centres of three neighbouring grains, using a Delaunay triangulation to account for an equivalent continuum media. Whereas the consistency of the macroscopic strain and the average mesoscopic strain is assessed, it is shown that a deviation from the normalised microscopic vertical displacement is an indicator of the heterogeneity of the mesoscopic strain field. The proposed mesoscopic analysis allows us to investigate these heterogeneities. Another important result is that even if the amplitude of the microscopic strain is small (approximately 100 times smaller) compared with the other strain measures, it confirms that the grains are not rigid and that their ultimate strain can be estimated using the proposed approach.
{"title":"Measuring coarse grain deformation by digital image correlation","authors":"C. Silvani, J. Réthoré, S. Nicaise","doi":"10.1111/str.12378","DOIUrl":"https://doi.org/10.1111/str.12378","url":null,"abstract":"This work presents results from oedometric compression of coarse granular material. Coarse granular media exhibit significant deformations making it complicated to predict the settlement of structures. In this paper, a measurement technique was developed for the analysis of two‐dimensional (2‐D) images of a deforming coarse granular medium to investigate its deformation. This was achieved by realising grain‐based image correlation to measure the grain transformation in gravel with the use of a digital image correlation technique. The 2‐D displacement fields enable us to explore the behaviour of granular media at different scales: microscopic, mesoscopic and macroscopic scales. The mesoscopic scale is defined from branches that connect the centres of three neighbouring grains, using a Delaunay triangulation to account for an equivalent continuum media. Whereas the consistency of the macroscopic strain and the average mesoscopic strain is assessed, it is shown that a deviation from the normalised microscopic vertical displacement is an indicator of the heterogeneity of the mesoscopic strain field. The proposed mesoscopic analysis allows us to investigate these heterogeneities. Another important result is that even if the amplitude of the microscopic strain is small (approximately 100 times smaller) compared with the other strain measures, it confirms that the grains are not rigid and that their ultimate strain can be estimated using the proposed approach.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2021-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12378","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47121423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Su, Xiaoping Ma, Wen Wang, Yiyi Yang, Jingyu Hu
Cumulative plastic damage caused during the low cycle fatigue (LCF) regime may seriously undermine the safety of the steel members and even lead to serious industrial accidents. Magnetic memory method (MMM), as a novel nondestructive testing technology, has been developed to evaluate the fatigue damage for the ferromagnetic material, but there is the lack of a quantitative description exists for the relationship between magnetic memory signals and cumulative plastic damage yet. In this paper, the strain‐based Jiles–Atherton hysteresis model under cyclic load during the LCF regime was established. Meanwhile, the LCF tests for S355 steel were performed, and the HSF signals on the surface of the specimen were collected under different loading cycles. Finite element (FE) simulations for coupling magnetic memory signals and cumulative plastic strain were carried out by the strain‐based Jiles–Atherton hysteresis model. Comparing with experimental results verifies the feasibility and accuracy of the FE method. The results indicate that the slope of the HSF signals fitting curve, K, as a characteristic parameter, has an exponential decrease as the cumulative plastic damage D increases. A general quantitative expression of the magneto‐damage model was built by discussing the influences of different factors on the K–D relation curves. It can be proved by verification that the magneto‐damage model provides a direct way for the quantitative evaluation of the cumulative plastic damage for the low‐carbon steel under LCF.
{"title":"Quantitative evaluation of cumulative plastic damage for ferromagnetic steel under low cycle fatigue based on magnetic memory method","authors":"S. Su, Xiaoping Ma, Wen Wang, Yiyi Yang, Jingyu Hu","doi":"10.1111/str.12379","DOIUrl":"https://doi.org/10.1111/str.12379","url":null,"abstract":"Cumulative plastic damage caused during the low cycle fatigue (LCF) regime may seriously undermine the safety of the steel members and even lead to serious industrial accidents. Magnetic memory method (MMM), as a novel nondestructive testing technology, has been developed to evaluate the fatigue damage for the ferromagnetic material, but there is the lack of a quantitative description exists for the relationship between magnetic memory signals and cumulative plastic damage yet. In this paper, the strain‐based Jiles–Atherton hysteresis model under cyclic load during the LCF regime was established. Meanwhile, the LCF tests for S355 steel were performed, and the HSF signals on the surface of the specimen were collected under different loading cycles. Finite element (FE) simulations for coupling magnetic memory signals and cumulative plastic strain were carried out by the strain‐based Jiles–Atherton hysteresis model. Comparing with experimental results verifies the feasibility and accuracy of the FE method. The results indicate that the slope of the HSF signals fitting curve, K, as a characteristic parameter, has an exponential decrease as the cumulative plastic damage D increases. A general quantitative expression of the magneto‐damage model was built by discussing the influences of different factors on the K–D relation curves. It can be proved by verification that the magneto‐damage model provides a direct way for the quantitative evaluation of the cumulative plastic damage for the low‐carbon steel under LCF.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2021-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45926014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Seven, M. A. Çankaya, Cetin Uysal, A. Taşdemirci, S. Saatci, M. Güden
The dynamic compression deformation of an in‐house cast concrete (average aggregate size of 2–2.5 mm) was modelled using the finite element (FE), element‐free Galerkin (EFG) and smooth particle Galerkin (SPG) methods to determine their capabilities of capturing the dynamic deformation. The numerical results were validated with those of the experimental split Hopkinson pressure bar tests. Both EFG and FE methods overestimated the failure stress and strain values, while the SPG method underestimated the peak stress. SPG showed similar load capacity profile with the experiment. At initial stages of the loading, all methods present similar behaviour. Nonetheless, as the loading continues, the SPG method predicts closer agreement of deformation profile and force histories. The increase in strength at high strain rate was due to both the rate sensitivity and lateral inertia caused by the confinement effect. The inertia effect of the material especially is effective at lower strain values and the strain rate sensitivity of the concrete becomes significant at higher strain values.
{"title":"Constitutive equation determination and dynamic numerical modelling of the compression deformation of concrete","authors":"S. Seven, M. A. Çankaya, Cetin Uysal, A. Taşdemirci, S. Saatci, M. Güden","doi":"10.1111/str.12377","DOIUrl":"https://doi.org/10.1111/str.12377","url":null,"abstract":"The dynamic compression deformation of an in‐house cast concrete (average aggregate size of 2–2.5 mm) was modelled using the finite element (FE), element‐free Galerkin (EFG) and smooth particle Galerkin (SPG) methods to determine their capabilities of capturing the dynamic deformation. The numerical results were validated with those of the experimental split Hopkinson pressure bar tests. Both EFG and FE methods overestimated the failure stress and strain values, while the SPG method underestimated the peak stress. SPG showed similar load capacity profile with the experiment. At initial stages of the loading, all methods present similar behaviour. Nonetheless, as the loading continues, the SPG method predicts closer agreement of deformation profile and force histories. The increase in strength at high strain rate was due to both the rate sensitivity and lateral inertia caused by the confinement effect. The inertia effect of the material especially is effective at lower strain values and the strain rate sensitivity of the concrete becomes significant at higher strain values.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2021-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12377","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42459330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to demonstrate the safety of engineered barriers for radwaste geological repositories, rich characterisations of bentonite hydro‐mechanical behaviour are essential. X‐ray computed tomography was used as the single input to measure both the full displacement field and water content in a heterogeneous bentonite sample resaturated in quasi‐isochoric conditions. Since large texture changes do not allow the use of digital volume correlation, this was achieved using 3D particle tracking to provide the kinematics in combination with calibrated and beam hardening‐corrected grey levels. Matching the grey level sampling with kinematics using a mesh‐based analysis, results show the development of heterogeneous swelling inside the cell and a final solid density gradient in the direction of water flow.
{"title":"Simultaneous fluid and solid density measurements in swelling clay using X‐ray microtomography and 3D particle tracking","authors":"F. Bernachy-Barbe, Kevin Alvarado","doi":"10.1111/str.12373","DOIUrl":"https://doi.org/10.1111/str.12373","url":null,"abstract":"In order to demonstrate the safety of engineered barriers for radwaste geological repositories, rich characterisations of bentonite hydro‐mechanical behaviour are essential. X‐ray computed tomography was used as the single input to measure both the full displacement field and water content in a heterogeneous bentonite sample resaturated in quasi‐isochoric conditions. Since large texture changes do not allow the use of digital volume correlation, this was achieved using 3D particle tracking to provide the kinematics in combination with calibrated and beam hardening‐corrected grey levels. Matching the grey level sampling with kinematics using a mesh‐based analysis, results show the development of heterogeneous swelling inside the cell and a final solid density gradient in the direction of water flow.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12373","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42810990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information","authors":"","doi":"10.1111/str.12324","DOIUrl":"https://doi.org/10.1111/str.12324","url":null,"abstract":"No abstract is available for this article.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12324","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41574486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This special issue entitled “Quantitative visualization testing techniques applied to civil engineering structures and materials” follows the organization of a series of thematic workshops entitled “Techniques d'Imagerie pour la Caracté risation des Matériaux et des Structures du Génie Civil” (image-based techniques for the characterization of materials and structures in civil engineering). The different editions took place in France in the cities of Clermont-Ferrand (March 20–21, 2014), Grenoble (March 10–11, 2016) and Champs-sur-Marne (April 4–5, 2019), bringing together about 50 PhD students, post-doc, early career or senior researchers who gave oral or poster presentations in the field of the experimental mechanics applied to civil engineering structures and materials. The present special issue illustrates how much the quantitative measurement experimental techniques in that research field have progressed and diversified within the last decade. Among the quantitative testing techniques used in the presented papers, one may want to highlight the various full-field or multipoint measurement methods: 2D and 3D Digital Image Correlation, Grid method, Particle Image Tracking, Particle Imagery Velocimetry, Digital Volume Correlation, Sampling moiré, Reflection photoelasticity, Optical fibre sensors, among others. These test methods are applied to heterogeneous materials: concrete, fibre-reinforced concrete, textile-reinforced concrete, granular materials, etc., from the microscopic or nanoscopic scale to the metre or decameter scale when applied to concrete bridges or masonry walls in this present special issue. Applications concern various environmental conditions such as high temperatures, different moisture contents, or loading conditions like high strain-rates testing. The underlying damage mechanisms are investigated by different methods like X-ray microtomography, synchrotron radiation or rapid neutron tomography. The wealth of experimental evidence brings better understanding of the mechanical behaviour of these civil engineering materials and structures and leads to substantial progress in the identification and the development of predictive modelling using Finite or Discrete Element, damage, cohesive zone or mixed-mode fracture models. We would like to acknowledge the contribution from many people which made this special issue possible. We wish to express our warm thanks to our reviewers for their time and efforts in reviewing papers and the authors for their work in submitting and revising their manuscript. Our gratitude also goes to Pr. Fabrice Pierron, former editor-in-chief of STRAIN Journal, for his guidance and support throughout the entire process. Wishing you a pleasant and inspiring reading,
{"title":"Strain special issue: Quantitative visualization testing techniques applied to civil engineering structures and materials","authors":"P. Forquin, E. Toussaint","doi":"10.1111/str.12353","DOIUrl":"https://doi.org/10.1111/str.12353","url":null,"abstract":"This special issue entitled “Quantitative visualization testing techniques applied to civil engineering structures and materials” follows the organization of a series of thematic workshops entitled “Techniques d'Imagerie pour la Caracté risation des Matériaux et des Structures du Génie Civil” (image-based techniques for the characterization of materials and structures in civil engineering). The different editions took place in France in the cities of Clermont-Ferrand (March 20–21, 2014), Grenoble (March 10–11, 2016) and Champs-sur-Marne (April 4–5, 2019), bringing together about 50 PhD students, post-doc, early career or senior researchers who gave oral or poster presentations in the field of the experimental mechanics applied to civil engineering structures and materials. The present special issue illustrates how much the quantitative measurement experimental techniques in that research field have progressed and diversified within the last decade. Among the quantitative testing techniques used in the presented papers, one may want to highlight the various full-field or multipoint measurement methods: 2D and 3D Digital Image Correlation, Grid method, Particle Image Tracking, Particle Imagery Velocimetry, Digital Volume Correlation, Sampling moiré, Reflection photoelasticity, Optical fibre sensors, among others. These test methods are applied to heterogeneous materials: concrete, fibre-reinforced concrete, textile-reinforced concrete, granular materials, etc., from the microscopic or nanoscopic scale to the metre or decameter scale when applied to concrete bridges or masonry walls in this present special issue. Applications concern various environmental conditions such as high temperatures, different moisture contents, or loading conditions like high strain-rates testing. The underlying damage mechanisms are investigated by different methods like X-ray microtomography, synchrotron radiation or rapid neutron tomography. The wealth of experimental evidence brings better understanding of the mechanical behaviour of these civil engineering materials and structures and leads to substantial progress in the identification and the development of predictive modelling using Finite or Discrete Element, damage, cohesive zone or mixed-mode fracture models. We would like to acknowledge the contribution from many people which made this special issue possible. We wish to express our warm thanks to our reviewers for their time and efforts in reviewing papers and the authors for their work in submitting and revising their manuscript. Our gratitude also goes to Pr. Fabrice Pierron, former editor-in-chief of STRAIN Journal, for his guidance and support throughout the entire process. Wishing you a pleasant and inspiring reading,","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12353","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43663415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Tengattini, S. Dal Pont, H. Cheikh Sleiman, F. Kisuka, M. Briffaut
Concrete has a tendency to spall, that is, to eject layers when subjected to high temperatures. This is an erratic phenomenon, and our understanding of the underlying physical process is still limited. A driving process is moisture transfer, whose experimental investigation has so far mostly been limited to macroscopic or point‐wise observations, limiting both our understanding and the validation of the proposed models. In this paper, a non‐contact technique, neutron imaging, is used to extract a the full‐field distribution of moisture in 3D and in real time, while the concrete is heated at high temperatures. This reveals a number of processes often underestimated or ignored in the traditional experimental approaches reported in the literature. Notably, the effect on the evolving moisture profiles of varying heating rates for multiple insulation techniques as well the strong influence of the addition of spalling‐mitigating additives is presented. The first ever example of neutron tomography of a spalled sample is also reported, and some preliminary analyses of the effect that moisture clog formation and heating rates have on it are revealed.
{"title":"Quantification of evolving moisture profiles in concrete samples subjected to temperature gradient by means of rapid neutron tomography: Influence of boundary conditions, hygro‐thermal loading history and spalling mitigation additives","authors":"A. Tengattini, S. Dal Pont, H. Cheikh Sleiman, F. Kisuka, M. Briffaut","doi":"10.1111/str.12371","DOIUrl":"https://doi.org/10.1111/str.12371","url":null,"abstract":"Concrete has a tendency to spall, that is, to eject layers when subjected to high temperatures. This is an erratic phenomenon, and our understanding of the underlying physical process is still limited. A driving process is moisture transfer, whose experimental investigation has so far mostly been limited to macroscopic or point‐wise observations, limiting both our understanding and the validation of the proposed models. In this paper, a non‐contact technique, neutron imaging, is used to extract a the full‐field distribution of moisture in 3D and in real time, while the concrete is heated at high temperatures. This reveals a number of processes often underestimated or ignored in the traditional experimental approaches reported in the literature. Notably, the effect on the evolving moisture profiles of varying heating rates for multiple insulation techniques as well the strong influence of the addition of spalling‐mitigating additives is presented. The first ever example of neutron tomography of a spalled sample is also reported, and some preliminary analyses of the effect that moisture clog formation and heating rates have on it are revealed.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12371","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47984468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The image‐based inertial impact (IBII) test has shown promise for measuring properties of composites at strain rates where existing test methods become unreliable due to inertial effects (> 102 s−1). Typically, the IBII tests are performed with a single camera, and therefore, to use surface measurements for material property identification, it is necessary to assume that the test is two‐dimensional. In this work, synchronised ultra‐high‐speed cameras are used to quantify the relevance of this assumption when nonuniform, through‐the‐thickness loading is applied to interlaminar samples. Initial experiments revealed that an angular misalignment of approximately 1° between the impact faces of the waveguide and projectile created a bending wave that propagated along the sample behind the axial pulse. Even under these conditions, consistent measurements of stiffness were made by assuming a linear distribution of the behaviour through‐the‐thickness. When the misalignment was reduced to 0.2°, the effects on single‐sided measurements were significantly reduced. The two alignment cases were compared to show that three‐dimensional loading had a small effect on stiffness identification (approximately 5% bias) relative to failure stress (approximately 30% bias). This study highlights the importance of impact alignment for reliable characterisation of the interlaminar failure stress and was used to establish guidelines for diagnosing loading issues from single‐sided measurements.
{"title":"Investigation of the 2D assumption in the image‐based inertial impact test","authors":"J. Van Blitterswyk, L. Fletcher, F. Pierron","doi":"10.1111/str.12369","DOIUrl":"https://doi.org/10.1111/str.12369","url":null,"abstract":"The image‐based inertial impact (IBII) test has shown promise for measuring properties of composites at strain rates where existing test methods become unreliable due to inertial effects (> 102 s−1). Typically, the IBII tests are performed with a single camera, and therefore, to use surface measurements for material property identification, it is necessary to assume that the test is two‐dimensional. In this work, synchronised ultra‐high‐speed cameras are used to quantify the relevance of this assumption when nonuniform, through‐the‐thickness loading is applied to interlaminar samples. Initial experiments revealed that an angular misalignment of approximately 1° between the impact faces of the waveguide and projectile created a bending wave that propagated along the sample behind the axial pulse. Even under these conditions, consistent measurements of stiffness were made by assuming a linear distribution of the behaviour through‐the‐thickness. When the misalignment was reduced to 0.2°, the effects on single‐sided measurements were significantly reduced. The two alignment cases were compared to show that three‐dimensional loading had a small effect on stiffness identification (approximately 5% bias) relative to failure stress (approximately 30% bias). This study highlights the importance of impact alignment for reliable characterisation of the interlaminar failure stress and was used to establish guidelines for diagnosing loading issues from single‐sided measurements.","PeriodicalId":51176,"journal":{"name":"Strain","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12369","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46132795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：