Fracture Testing of Honeycomb Core Sandwich Composites Using the DCB-UBM Test

Vishnu Saseendran, Christian Berggreen, Leif A. Carlsson

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Abstract

Face/core debonds in sandwich structures cause loss of integrity of sandwich structures. The debond problem in honeycomb core sandwich composites has not been widely studied. A suitable fracture approach coupled with experimental validation is paramount to determine the fracture resistance of the face/core interface. In this paper, a novel test-rig exploiting the double cantilever beam-uneven bending moments (DCB-UBM) concept is used to determine the fracture toughness of aircraft type honeycomb core sandwich composites as a function of the phase angle (mode-mixity), within the framework of Linear Elastic Fracture Mechanics (LEFM). The Double Cantilever Beam subjected to Uneven Bending Moments (DCB-UBM) test set-up, which was introduced by Sørensen.et.al [1], circumvents any dependency of the pre-crack length in calculation of Gc. The new test setup is based on rotary actuators which are able to slide on rails to follow the specimen’s deformation kinematics when subjected to pure rotations, as schematically shown in Figure 1. The robustness of the new test rig is demonstrated by performing pure mode-I fracture characterization of the face/core interface of a typical aircraft sandwich specimen consisting of CFRP/GFRP face sheet and a Nomex based honeycomb core. The J-integral was calculated analytically using the moments and subsequently the fracture resistance curve developed over the test domain as a function of time is averaged.
Original languageEnglish
Title of host publicationProceedings of the 20th International Conference on Composite Materials (ICCM20)
Number of pages5
PublisherICCM20 Secretariat
Publication date2015
Publication statusPublished - 2015
Event20th International Conference on Composite Materials (ICCM20) - Copenhagen, Denmark
Duration: 19 Jul 201524 Jul 2015
Conference number: 20

Conference

Conference20th International Conference on Composite Materials (ICCM20)
Number20
CountryDenmark
CityCopenhagen
Period19/07/201524/07/2015

Keywords

  • Sandwich composites
  • DCB-UBM
  • Honeycombs
  • CSDE-method

Cite this

Saseendran, V., Berggreen, C., & Carlsson, L. A. (2015). Fracture Testing of Honeycomb Core Sandwich Composites Using the DCB-UBM Test. In Proceedings of the 20th International Conference on Composite Materials (ICCM20) ICCM20 Secretariat.
Saseendran, Vishnu ; Berggreen, Christian ; Carlsson, Leif A. / Fracture Testing of Honeycomb Core Sandwich Composites Using the DCB-UBM Test. Proceedings of the 20th International Conference on Composite Materials (ICCM20). ICCM20 Secretariat, 2015.
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abstract = "Face/core debonds in sandwich structures cause loss of integrity of sandwich structures. The debond problem in honeycomb core sandwich composites has not been widely studied. A suitable fracture approach coupled with experimental validation is paramount to determine the fracture resistance of the face/core interface. In this paper, a novel test-rig exploiting the double cantilever beam-uneven bending moments (DCB-UBM) concept is used to determine the fracture toughness of aircraft type honeycomb core sandwich composites as a function of the phase angle (mode-mixity), within the framework of Linear Elastic Fracture Mechanics (LEFM). The Double Cantilever Beam subjected to Uneven Bending Moments (DCB-UBM) test set-up, which was introduced by S{\o}rensen.et.al [1], circumvents any dependency of the pre-crack length in calculation of Gc. The new test setup is based on rotary actuators which are able to slide on rails to follow the specimen’s deformation kinematics when subjected to pure rotations, as schematically shown in Figure 1. The robustness of the new test rig is demonstrated by performing pure mode-I fracture characterization of the face/core interface of a typical aircraft sandwich specimen consisting of CFRP/GFRP face sheet and a Nomex based honeycomb core. The J-integral was calculated analytically using the moments and subsequently the fracture resistance curve developed over the test domain as a function of time is averaged.",
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Saseendran, V, Berggreen, C & Carlsson, LA 2015, Fracture Testing of Honeycomb Core Sandwich Composites Using the DCB-UBM Test. in Proceedings of the 20th International Conference on Composite Materials (ICCM20). ICCM20 Secretariat, 20th International Conference on Composite Materials (ICCM20), Copenhagen, Denmark, 19/07/2015.

Fracture Testing of Honeycomb Core Sandwich Composites Using the DCB-UBM Test. / Saseendran, Vishnu; Berggreen, Christian; Carlsson, Leif A.

Proceedings of the 20th International Conference on Composite Materials (ICCM20). ICCM20 Secretariat, 2015.

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

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T1 - Fracture Testing of Honeycomb Core Sandwich Composites Using the DCB-UBM Test

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N2 - Face/core debonds in sandwich structures cause loss of integrity of sandwich structures. The debond problem in honeycomb core sandwich composites has not been widely studied. A suitable fracture approach coupled with experimental validation is paramount to determine the fracture resistance of the face/core interface. In this paper, a novel test-rig exploiting the double cantilever beam-uneven bending moments (DCB-UBM) concept is used to determine the fracture toughness of aircraft type honeycomb core sandwich composites as a function of the phase angle (mode-mixity), within the framework of Linear Elastic Fracture Mechanics (LEFM). The Double Cantilever Beam subjected to Uneven Bending Moments (DCB-UBM) test set-up, which was introduced by Sørensen.et.al [1], circumvents any dependency of the pre-crack length in calculation of Gc. The new test setup is based on rotary actuators which are able to slide on rails to follow the specimen’s deformation kinematics when subjected to pure rotations, as schematically shown in Figure 1. The robustness of the new test rig is demonstrated by performing pure mode-I fracture characterization of the face/core interface of a typical aircraft sandwich specimen consisting of CFRP/GFRP face sheet and a Nomex based honeycomb core. The J-integral was calculated analytically using the moments and subsequently the fracture resistance curve developed over the test domain as a function of time is averaged.

AB - Face/core debonds in sandwich structures cause loss of integrity of sandwich structures. The debond problem in honeycomb core sandwich composites has not been widely studied. A suitable fracture approach coupled with experimental validation is paramount to determine the fracture resistance of the face/core interface. In this paper, a novel test-rig exploiting the double cantilever beam-uneven bending moments (DCB-UBM) concept is used to determine the fracture toughness of aircraft type honeycomb core sandwich composites as a function of the phase angle (mode-mixity), within the framework of Linear Elastic Fracture Mechanics (LEFM). The Double Cantilever Beam subjected to Uneven Bending Moments (DCB-UBM) test set-up, which was introduced by Sørensen.et.al [1], circumvents any dependency of the pre-crack length in calculation of Gc. The new test setup is based on rotary actuators which are able to slide on rails to follow the specimen’s deformation kinematics when subjected to pure rotations, as schematically shown in Figure 1. The robustness of the new test rig is demonstrated by performing pure mode-I fracture characterization of the face/core interface of a typical aircraft sandwich specimen consisting of CFRP/GFRP face sheet and a Nomex based honeycomb core. The J-integral was calculated analytically using the moments and subsequently the fracture resistance curve developed over the test domain as a function of time is averaged.

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KW - CSDE-method

M3 - Article in proceedings

BT - Proceedings of the 20th International Conference on Composite Materials (ICCM20)

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Saseendran V, Berggreen C, Carlsson LA. Fracture Testing of Honeycomb Core Sandwich Composites Using the DCB-UBM Test. In Proceedings of the 20th International Conference on Composite Materials (ICCM20). ICCM20 Secretariat. 2015