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In-plane compression of sandwich panels with debonds
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.ORCID iD: 0000-0002-9207-3404
2010 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 92, no 2, 532-540 p.Article in journal (Refereed) Published
Abstract [en]

The post failure behaviour of in-plane compression loaded sandwich panels is studied by considering the structural response of such panels with symmetrically located edge debonds. A parametric finite element model is used to determine the influence of different material and geometrical properties on the failure progression, i.e. after initiation of damage. The investigated failure modes are buckling of the debonded face sheets, debond propagation and face sheet failure. The postbuckling failure mode is mainly determined by the fracture toughness of the core and the bending stiffness and strength of the face sheets. The presented approach and results can be used to determine how sandwich panels should be constituted, or not, to promote damage progression favourable for efficient energy absorption during in-plane crushing. The prolonged damage propagation is very complex as it is strongly non-linear and depends on a combination of stiffness, strength and geometry of the constituent materials.

Place, publisher, year, edition, pages
Oxford, UK: Elsevier , 2010. Vol. 92, no 2, 532-540 p.
Keyword [en]
Sandwich; Fracture; Finite element analysis (FEA)
National Category
Composite Science and Engineering
URN: urn:nbn:se:kth:diva-11155DOI: 10.1016/j.compstruct.2009.08.039ISI: 000271561100038ScopusID: 2-s2.0-70349801487OAI: diva2:236435

QC 20100728

Available from: 2009-09-23 Created: 2009-09-23 Last updated: 2016-05-16Bibliographically approved
In thesis
1. In-plane Compressive Response of Sandwich Panels
Open this publication in new window or tab >>In-plane Compressive Response of Sandwich Panels
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The high specific bending stiffness of sandwich structures can with advantage be used in vehicles to reduce their weight and thereby potentially also their fuel consumption. However, the structure must not only meet the in-service requirements but also provide sufficient protection of the vehicle passengers in a crash situation. The in-plane compressive response of sandwich panels is investigated in this thesis, with the objective to develop a methodology capable of determining if the structural response is likely to be favourable in an energy absorption perspective. Experiments were conducted to identify possible initial failure and collapse modes. The initial failure modes of sandwich panels compressed quasi-statically in the in-plane direction were identified as global buckling, local buckling (wrinkling) and face sheet fracture. Global buckling promotes continued folding of the structure when compressed beyond failure initiation. Face sheet fracture and wrinkling can promote collapse in the form of unstable debond crack growth, stable end-crushing or ductile in-plane shear collapse. Both the unstable debond crack propagation and the stable end-crushing are related to debond crack propagation, whereas the ductile in-plane shear mode is related to microbuckling of the face sheets.

The collapse behaviour of sandwich configurations initially failing due to wrinkling or face sheet fracture was investigated, using a finite element model. The model was used to determine if the panels were likely to collapse in unstable debond propagation or in a more stable end-crushing mode, promoting high energy absorption. The collapse behaviour is mainly governed by the relation between the fracture toughness of the core and the bending stiffness and strength of the face sheets. The model was successfully used to design sandwich panels for different collapse behaviour. The proposed method could therefore be used in the design process of sandwich panels subjected to in-plane compressive loads.During a crash situation the accelerations on passengers must be kept below life threatening levels. The extreme peak loads in the structure must therefore be limited. This can be achieved by different kind of triggering features.Panels with either chamfered face sheets or with grooves on the loaded edges were investigated in this thesis. The peak load was reduced with panels incorporating either of the two triggering features. Another positive effect was that the plateau load following failure initiation was increased by the triggers. This clearly illustrates that triggers can be used to promote favourable response in sandwich panels.

Vehicles are harmful to the environment not only during in-serve use, but during their entire life-cycle. By use of renewable materials the impact on the environment can be reduced. The in-plane compressive response of bio-based sandwich panels was therefore investigated. Panels with hemp fibre laminates showed potential for high energy absorption and panels with a balsa wood core behaved particular well. The ductile in-plane shear collapse mode of these panels resulted in the highest energy absorption of all investigated sandwich configurations.


Place, publisher, year, edition, pages
Stockholm: KTH, 2009. xi, 27 p.
Trita-AVE, ISSN 1651-7660 ; 2009:67
Sandwich, Finite Element Analysis (FEA), Fracture, In-plane compression
National Category
Other Materials Engineering Condensed Matter Physics
urn:nbn:se:kth:diva-11160 (URN)978-91-7415-447-4 (ISBN)
Public defence
2009-10-26, Sal F3, Lindstedtsvägen 26, Stockholm, 10:15 (English)
QC 20100728Available from: 2009-10-06 Created: 2009-09-23 Last updated: 2010-07-28Bibliographically approved

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