Unusual nonlinear switching in branched carbon nanotube nanocomposites
Abstract In this experimental study, we investigate the nonlinear dynamic response of nanocomposite beams composed of polybutylene terephthalate (PBT) and branched carbon nanotubes (bCNTs). By varying the weight fraction of bCNTs, we obtain frequency response curves for cantilever specimens under ha...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2023-03-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-023-32331-y |
| _version_ | 1797853844242169856 |
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| author | Walter Lacarbonara Sawan Kumar Guruva Biagio Carboni Beate Krause Andreas Janke Giovanni Formica Giulia Lanzara |
| author_facet | Walter Lacarbonara Sawan Kumar Guruva Biagio Carboni Beate Krause Andreas Janke Giovanni Formica Giulia Lanzara |
| author_sort | Walter Lacarbonara |
| collection | DOAJ |
| description | Abstract In this experimental study, we investigate the nonlinear dynamic response of nanocomposite beams composed of polybutylene terephthalate (PBT) and branched carbon nanotubes (bCNTs). By varying the weight fraction of bCNTs, we obtain frequency response curves for cantilever specimens under harmonic base excitations, measuring the tip displacement via 3D scanning laser vibrometry. Our findings reveal a surprising nonlinear softening trend in the steady-state response of the cantilevers, which gets switched into hardening for higher bCNT weight fractions and increasing oscillation amplitudes. The interaction of bCNTs with the thermoplastic hosting matrix results in stick-slip hysteresis, causing a softening nonlinearity that counteracts the geometric hardening associated with the nonlinear curvature of the first mode of the cantilever. However, when the weight fraction of bCNTs is greater than 1%, the bridging of the branched CNTs leads to the formation of a strong network that contributes to the hardening response at higher oscillation amplitudes. This mechanical behavior is detected by the trend of the nonlinear harmonic spectra and the equivalent damping ratio estimated using the half-power bandwidth method. To predict the observed unusual experimental behavior, we use a nonlinear mathematical model of the nanocomposite cantilever samples derived from a 3D mesoscale hysteretic model of the PBT/bCNT material. Our results suggest that the presence of bCNTs in a thermoplastic matrix is the main driver of the highly tunable nonlinear stiffness and damping capacity of the material. The reported experimental and modeling results provide valuable insights into the nonlinear dynamic behavior of PBT/bCNT nanocomposites and have potential applications in the design of advanced materials with tailored mechanical properties. |
| first_indexed | 2024-04-09T19:57:20Z |
| format | Article |
| id | doaj.art-4315615e99f548cc96c44d7cd8194598 |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-09T19:57:20Z |
| publishDate | 2023-03-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-4315615e99f548cc96c44d7cd81945982023-04-03T05:24:37ZengNature PortfolioScientific Reports2045-23222023-03-0113111210.1038/s41598-023-32331-yUnusual nonlinear switching in branched carbon nanotube nanocompositesWalter Lacarbonara0Sawan Kumar Guruva1Biagio Carboni2Beate Krause3Andreas Janke4Giovanni Formica5Giulia Lanzara6Department of Structural and Geotechnical Engineering, Sapienza University of RomeDepartment of Structural and Geotechnical Engineering, Sapienza University of RomeDepartment of Structural and Geotechnical Engineering, Sapienza University of RomeDepartment of Functional Nanocomposites and Blends, Leibniz Institute of Polymer Research DresdenCenter for Multi-Scale Characterization, Leibniz Institute of Polymer Research DresdenDepartment of Architecture, RomaTre UniversityDepartment of Engineering, RomaTre UniversityAbstract In this experimental study, we investigate the nonlinear dynamic response of nanocomposite beams composed of polybutylene terephthalate (PBT) and branched carbon nanotubes (bCNTs). By varying the weight fraction of bCNTs, we obtain frequency response curves for cantilever specimens under harmonic base excitations, measuring the tip displacement via 3D scanning laser vibrometry. Our findings reveal a surprising nonlinear softening trend in the steady-state response of the cantilevers, which gets switched into hardening for higher bCNT weight fractions and increasing oscillation amplitudes. The interaction of bCNTs with the thermoplastic hosting matrix results in stick-slip hysteresis, causing a softening nonlinearity that counteracts the geometric hardening associated with the nonlinear curvature of the first mode of the cantilever. However, when the weight fraction of bCNTs is greater than 1%, the bridging of the branched CNTs leads to the formation of a strong network that contributes to the hardening response at higher oscillation amplitudes. This mechanical behavior is detected by the trend of the nonlinear harmonic spectra and the equivalent damping ratio estimated using the half-power bandwidth method. To predict the observed unusual experimental behavior, we use a nonlinear mathematical model of the nanocomposite cantilever samples derived from a 3D mesoscale hysteretic model of the PBT/bCNT material. Our results suggest that the presence of bCNTs in a thermoplastic matrix is the main driver of the highly tunable nonlinear stiffness and damping capacity of the material. The reported experimental and modeling results provide valuable insights into the nonlinear dynamic behavior of PBT/bCNT nanocomposites and have potential applications in the design of advanced materials with tailored mechanical properties.https://doi.org/10.1038/s41598-023-32331-y |
| spellingShingle | Walter Lacarbonara Sawan Kumar Guruva Biagio Carboni Beate Krause Andreas Janke Giovanni Formica Giulia Lanzara Unusual nonlinear switching in branched carbon nanotube nanocomposites Scientific Reports |
| title | Unusual nonlinear switching in branched carbon nanotube nanocomposites |
| title_full | Unusual nonlinear switching in branched carbon nanotube nanocomposites |
| title_fullStr | Unusual nonlinear switching in branched carbon nanotube nanocomposites |
| title_full_unstemmed | Unusual nonlinear switching in branched carbon nanotube nanocomposites |
| title_short | Unusual nonlinear switching in branched carbon nanotube nanocomposites |
| title_sort | unusual nonlinear switching in branched carbon nanotube nanocomposites |
| url | https://doi.org/10.1038/s41598-023-32331-y |
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