Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography
Lock-In thermography can be used to investigate elastic stresses and dissipative effects in dynamic processes like crack propagation. The evaluation normally is performed with a Discrete Fourier Transformation resulting in E- and D-Amplitude and phase images. The E-Amplitude images give information...
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Gruppo Italiano Frattura
2019-04-01
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| Series: | Fracture and Structural Integrity |
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| Online Access: | https://www.fracturae.com/index.php/fis/article/view/2278/2465 |
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| author | Jurgen Bar Ralf Urbanek |
| author_facet | Jurgen Bar Ralf Urbanek |
| author_sort | Jurgen Bar |
| collection | DOAJ |
| description | Lock-In thermography can be used to investigate elastic stresses and dissipative effects in dynamic processes like crack propagation. The evaluation normally is performed with a Discrete Fourier Transformation resulting in E- and D-Amplitude and phase images. The E-Amplitude images give information about the stress distribution, the D-Amplitude is connected with dissipated energies. The observed changes in the E-amplitude values can be attributed to a change in the stress state at the crack tip due to bending of the specimen caused by the propagating crack. In the crack propagation experiments the maximum value of the D-Mode in the area in front of the crack tip was found to be constant. The appearance of higher harmonic modes in the evaluation raises the question if the Discrete Fourier Transformation is the appropriate method for a quantitative evaluation of dissipative effects. Experiments performed on flat specimens show that the temperature change due to dissipative effects could not be described with a sine wave with the double loading frequency. Therefore, a quantitative determination of dissipated energies using the Discrete Fourier Transformation is impossible. For a quantitative determination of dissipated energies a new evaluation method has to be developed. |
| format | Article |
| id | doaj-art-56827dfec8a94cd7af1979c87766742b |
| institution | Kabale University |
| issn | 1971-8993 |
| language | English |
| publishDate | 2019-04-01 |
| publisher | Gruppo Italiano Frattura |
| record_format | Article |
| series | Fracture and Structural Integrity |
| spelling | doaj-art-56827dfec8a94cd7af1979c87766742b2025-01-02T23:01:35ZengGruppo Italiano FratturaFracture and Structural Integrity1971-89932019-04-01134856357010.3221/IGF-ESIS.48.5410.3221/IGF-ESIS.48.54Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In ThermographyJurgen BarRalf UrbanekLock-In thermography can be used to investigate elastic stresses and dissipative effects in dynamic processes like crack propagation. The evaluation normally is performed with a Discrete Fourier Transformation resulting in E- and D-Amplitude and phase images. The E-Amplitude images give information about the stress distribution, the D-Amplitude is connected with dissipated energies. The observed changes in the E-amplitude values can be attributed to a change in the stress state at the crack tip due to bending of the specimen caused by the propagating crack. In the crack propagation experiments the maximum value of the D-Mode in the area in front of the crack tip was found to be constant. The appearance of higher harmonic modes in the evaluation raises the question if the Discrete Fourier Transformation is the appropriate method for a quantitative evaluation of dissipative effects. Experiments performed on flat specimens show that the temperature change due to dissipative effects could not be described with a sine wave with the double loading frequency. Therefore, a quantitative determination of dissipated energies using the Discrete Fourier Transformation is impossible. For a quantitative determination of dissipated energies a new evaluation method has to be developed.https://www.fracturae.com/index.php/fis/article/view/2278/2465Aluminum alloyCrack propagationDissipated energyFatigueThermography |
| spellingShingle | Jurgen Bar Ralf Urbanek Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography Fracture and Structural Integrity Aluminum alloy Crack propagation Dissipated energy Fatigue Thermography |
| title | Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography |
| title_full | Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography |
| title_fullStr | Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography |
| title_full_unstemmed | Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography |
| title_short | Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography |
| title_sort | determination of dissipated energy in fatigue crack propagation experiments with lock in thermography |
| topic | Aluminum alloy Crack propagation Dissipated energy Fatigue Thermography |
| url | https://www.fracturae.com/index.php/fis/article/view/2278/2465 |
| work_keys_str_mv | AT jurgenbar determinationofdissipatedenergyinfatiguecrackpropagationexperimentswithlockinthermography AT ralfurbanek determinationofdissipatedenergyinfatiguecrackpropagationexperimentswithlockinthermography |