Characterizing the Anisotropic Elastic Properties of Auxetic Structures by Impulse Excitation Technique Combined with Inverse Parameter Identification.
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| Title: | Characterizing the Anisotropic Elastic Properties of Auxetic Structures by Impulse Excitation Technique Combined with Inverse Parameter Identification. |
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| Authors: | Rech, Julian1 (AUTHOR) yuchen.leng@th-koeln.de, Leng, Yuchen2 (AUTHOR), Reinholz, Stefan2,3 (AUTHOR), Dresbach, Christian1 (AUTHOR) christoph.hartl@th-koeln.de, Katrakova-Krüger, Danka2 (AUTHOR), Hartl, Christoph3 (AUTHOR) |
| Source: | Materials (1996-1944). Jun2026, Vol. 19 Issue 12, p2479. 20p. |
| Subjects: | Auxetic materials, Finite element method, Poisson's ratio, Solid freeform fabrication, Polylactic acid, Anisotropic crystals |
| Abstract: | Auxetic metamaterials exhibit unique mechanical behavior due to their negative Poisson's ratio, but reliable determination of their effective elastic properties remains challenging. In this study, an experimental–numerical approach is proposed to characterize additively manufactured polylactic acid (PLA)-based auxetic sandwich structures. Material properties were first assessed using tensile testing, melt flow rate/volume rate (MFR/MVR) measurements, Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dilatometry, and nanoindentation, revealing stable mechanical behavior, good processability, and slight increases in crystallinity induced by the printing process. Impulse excitation technique (IET) measurements provided highly reproducible resonant frequencies, demonstrating a strong dependence on core geometry and orientation. However, classical ASTM-based evaluation yielded non-physical elastic properties, highlighting its limitations for architected metamaterials. Finite element modal analyses, combined with inverse parameter identification, enabled the determination of effective elastic properties using a transversely isotropic homogenized model. This approach significantly improved the agreement between experimental and numerical results. The findings revealed pronounced anisotropy and orientation-dependent auxetic behavior, including a negative Poisson's ratio for specific configurations. The proposed methodology provides a suitable framework for the reliable characterization and design of complex metamaterials. [ABSTRACT FROM AUTHOR] |
| Copyright of Materials (1996-1944) is the property of MDPI and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 194907553 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Characterizing the Anisotropic Elastic Properties of Auxetic Structures by Impulse Excitation Technique Combined with Inverse Parameter Identification. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Rech%2C+Julian%22">Rech, Julian</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> yuchen.leng@th-koeln.de</i><br /><searchLink fieldCode="AR" term="%22Leng%2C+Yuchen%22">Leng, Yuchen</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Reinholz%2C+Stefan%22">Reinholz, Stefan</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Dresbach%2C+Christian%22">Dresbach, Christian</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> christoph.hartl@th-koeln.de</i><br /><searchLink fieldCode="AR" term="%22Katrakova-Krüger%2C+Danka%22">Katrakova-Krüger, Danka</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Hartl%2C+Christoph%22">Hartl, Christoph</searchLink><relatesTo>3</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Materials+%281996-1944%29%22">Materials (1996-1944)</searchLink>. Jun2026, Vol. 19 Issue 12, p2479. 20p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Auxetic+materials%22">Auxetic materials</searchLink><br /><searchLink fieldCode="DE" term="%22Finite+element+method%22">Finite element method</searchLink><br /><searchLink fieldCode="DE" term="%22Poisson's+ratio%22">Poisson's ratio</searchLink><br /><searchLink fieldCode="DE" term="%22Solid+freeform+fabrication%22">Solid freeform fabrication</searchLink><br /><searchLink fieldCode="DE" term="%22Polylactic+acid%22">Polylactic acid</searchLink><br /><searchLink fieldCode="DE" term="%22Anisotropic+crystals%22">Anisotropic crystals</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Auxetic metamaterials exhibit unique mechanical behavior due to their negative Poisson's ratio, but reliable determination of their effective elastic properties remains challenging. In this study, an experimental–numerical approach is proposed to characterize additively manufactured polylactic acid (PLA)-based auxetic sandwich structures. Material properties were first assessed using tensile testing, melt flow rate/volume rate (MFR/MVR) measurements, Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dilatometry, and nanoindentation, revealing stable mechanical behavior, good processability, and slight increases in crystallinity induced by the printing process. Impulse excitation technique (IET) measurements provided highly reproducible resonant frequencies, demonstrating a strong dependence on core geometry and orientation. However, classical ASTM-based evaluation yielded non-physical elastic properties, highlighting its limitations for architected metamaterials. Finite element modal analyses, combined with inverse parameter identification, enabled the determination of effective elastic properties using a transversely isotropic homogenized model. This approach significantly improved the agreement between experimental and numerical results. The findings revealed pronounced anisotropy and orientation-dependent auxetic behavior, including a negative Poisson's ratio for specific configurations. The proposed methodology provides a suitable framework for the reliable characterization and design of complex metamaterials. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Materials (1996-1944) is the property of MDPI and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.3390/ma19122479 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 20 StartPage: 2479 Subjects: – SubjectFull: Auxetic materials Type: general – SubjectFull: Finite element method Type: general – SubjectFull: Poisson's ratio Type: general – SubjectFull: Solid freeform fabrication Type: general – SubjectFull: Polylactic acid Type: general – SubjectFull: Anisotropic crystals Type: general Titles: – TitleFull: Characterizing the Anisotropic Elastic Properties of Auxetic Structures by Impulse Excitation Technique Combined with Inverse Parameter Identification. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Rech, Julian – PersonEntity: Name: NameFull: Leng, Yuchen – PersonEntity: Name: NameFull: Reinholz, Stefan – PersonEntity: Name: NameFull: Dresbach, Christian – PersonEntity: Name: NameFull: Katrakova-Krüger, Danka – PersonEntity: Name: NameFull: Hartl, Christoph IsPartOfRelationships: – BibEntity: Dates: – D: 15 M: 06 Text: Jun2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 19961944 Numbering: – Type: volume Value: 19 – Type: issue Value: 12 Titles: – TitleFull: Materials (1996-1944) Type: main |
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