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Strength of Sandwich Panels Loaded in In-plane Compression
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The use of composite materials in vehicle structures could reduce the weight and thereby the fuel consumption of vehicles.

As the road safety of the vehicles must be ensured, it is vital that the energy absorbing capability of the composite materials are similar to or better than the commonly used steel structures. The high specific bending stiffness of sandwich structures can with advantage be used in vehicles, provided that the structural behaviour during a crash situation is well understood and possible to predict. The purpose of this thesis is to identify and if possible to describe the failure initiation and progression in in-plane compression loaded sandwich panels.

An experimental study on in-plane compression loaded sandwich panels with two different material concepts was conducted. Digital speckle photography (DSP) was used to record the displacement field of one outer face-sheet surface during compression. The sandwich panels with glass fibre preimpregnated face-sheets and a polymer foam core failed due to disintegration of the face-sheets from the core, whereas the sandwich panels with sheet molding compound face-sheets and a balsa core failed in progressive end-crushing. A simple semi-empirical model was developed to describe the structural response before and after initial failure.

The postfailure behaviour of in-plane compression loaded sandwich panels was studied by considering the structural behaviour of sandwich panels with edge debonds. A parametrical finite element model was used to determine the influence of different material and geometrical properties on the buckling and postbuckling failure loads. The postbuckling failure modes studied were debond crack propagation and face-sheet failure. It could be concluded that the postbuckling failure modes were mainly determined by the ratio between the fracture toughness of the face-core interface and the bending stiffness of the face-sheets.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , xi, 16 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2007:73
Keyword [en]
sandwich, in-plane compression, energy absorption, debond, postbuckling
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4558ISBN: 978-91-7178-814-6 (print)OAI: oai:DiVA.org:kth-4558DiVA: diva2:12847
Presentation
2007-12-14, D31, Lindstedtsvägen 17, Kungliga Tekniska Högskolan, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20101111Available from: 2007-11-25 Created: 2007-11-25 Last updated: 2010-11-11Bibliographically approved
List of papers
1. Energy Absorption of Sandwich Panels Subjected to In-plane Loads
Open this publication in new window or tab >>Energy Absorption of Sandwich Panels Subjected to In-plane Loads
2006 (English)In: 8th Biennial ASME Conference on EngineeringSystems Design and Analysis, Torino, Italy, 4-7 July, 2006: Volume 3: Dynamic Systems and Controls, Symposium on Design and Analysis of Advanced Structures, and Tribology, 2006, 739-747 p.Conference paper, Published paper (Refereed)
Abstract [en]

Theenergy absorption mechanisms of sandwich panels subjected to in-plane compressionare studied. Quasi-static experiments are performed and analysed in orderto support the development of a modelling strategy for failureinitiation and propagation in sandwich panels. The test specimens consistof balsa wood cores and glass-fibre reinforced polyester faces. Duringcompression of a tested panel, the displacement field on oneouter face is measured using a digital speckle photography (DSP)equipment. The absorbed energy is related to debonding, delamination andcrushing of the face sheets and crushing of the core.At initial failure, the load drops dramatically and is thenrelatively constant during continued compression. The energy per unit lengthnecessary for propagation of the damage is considerably lower thanfor damage initiation. Assuming that the damage propagation is uniformthrough the thickness of the panels a simple model ofdamage growth is developed. Calibration of the model is howeverdubious due to the large scatter in the experimental results.The studied material shows damage mechanisms favourable for efficient energyabsorption but the behaviour is far from being optimal.

Keyword
Computer simulation; Delamination; Energy absorption; Loads (forces); Mathematical models; Structural
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-11152 (URN)10.1115/ESDA2006-95771 (DOI)000249558200084 ()2-s2.0-33845767479 (Scopus ID)0-7918-4250-9 (ISBN)
Conference
8th Biennial ASME Conference on Engineering Systems Design and Analysis, Torino, Italy, 2006
Note

QC 20100728

Available from: 2009-09-23 Created: 2009-09-23 Last updated: 2016-05-16Bibliographically approved
2. Strength of In-plane Compression Loaded Sandwich Panels with Debonds
Open this publication in new window or tab >>Strength of In-plane Compression Loaded Sandwich Panels with Debonds
(English)Manuscript (Other academic)
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-7733 (URN)
Note

QC 20101111

Available from: 2007-11-25 Created: 2007-11-25 Last updated: 2016-05-16Bibliographically approved

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Citation style
  • apa
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  • Other locale
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Output format
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