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Sandwich panel containing Kraft paper honeycomb core and wood composite skin
Development of Novel Hollow Core Composite Panels for Value-Added Secondary Applications
By: Zheng Chen,
Faculty of Forestry, University of Toronto
http://www.valuetowood.ca/
Funded by a Value to Wood Program of Natural Resources Canada
Collaboration with University of British Columbia
FPInnovations-Forintek in Quebec city
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System of project
Sample prepare and bending test in UBC
Tests of compression, shear and creep in FPInnovation-Forintek
Development of finite element (FE) model in UT
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Kraft paper honeycomb panel applications in furniture industry
• Excellent strength to weight ratio• Low material cost• Smooth skin• Excellent fatigue resistance• Excellent crush strength and stiffness• Structural integrity• Exceptionally high strengths available
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Project goal
To characterize the influence of parameters on the material properties of sandwich panel containing Kraft paper honeycomb core and wood composite skins for developing panels with higher ratio of stiffness to weight
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Material properties evaluated
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Material properties evaluated
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Material properties evaluated
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Material properties evaluated
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Material properties evaluated
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Parameters influence on material properties
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Development of FE model
These FE model were developed by using the COSMOSWORK 2008 Advanced Professional (COSMOSWORK 2008 SP2.1)
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Development of FE modelThe element selection for FE model
FE meshed modelLinear element
Parabolic element
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Development of FE modelType of FE model developed in this
study
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Development of FE modelFE model for predicting Ex
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Development of FE modelFE model for predicting Ex
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Development of FE modelFE model for predicting Ex
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Development of FE modelFE model for predicting bending
stiffness
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Development of FE modelFE model for predicting bending
stiffness
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Development of FE modelProcedure of model establishment
Using data from Karademir et al (2004) as Ex and Ey of central layer of 3D FE model for all types Of honeycomb core
Obtaining Ez, Gxz and Gyz of central layer of FE model for expanded honeycomb coreby fitting the test data from Advanced Honeycomb Technologies Inc.(2007)
Using relative data from Youngquist(1999) for material properties of HB,MDF and PW skins
Obtaining Ez, Gxz and Gyz of central layer of FE model for corrugated and laminated honeycomb core by fitting the test data from FPInnovations (Chen et al 2011)
Obtaining material properties of central layer for uniform entity FE model for creep and bookshelf
Prediction the influence of parameters that the test data did not cover
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Comparison of FE model predictions and test data
Edgewise compression
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Comparison of FE model predictions and test data
Edgewise compression
Note: all panels are made from expanded core and MDF skins and have 31.75 mm cell size.
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Comparison of FE model predictions and test data
Interlaminar shear loading
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Comparison of FE model predictions and test data
Interlaminar shear loading
Note: all panels are made from expanded core and MDF skins and have 31.75 mm cell size.
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Comparison of FE model predictions and test data
Flexural creep
Primary Secondary Tertiary
Creep measured in Forintek
Expanded honeycomb core and HB skin. Sample span in y direction
Note: loading level for all sample is 54.25 N
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Comparison of FE model predictions and test data
Flexural creep
Primary Secondary Tertiary
Creep measured in Forintek
FE model predictions
Expanded honeycomb core and HB skin. Sample span in y direction
These FE model were developed by using the Nonlinear method and material creep effect (based on Baily-Newton law) of COSMOSWORK 2008 Advanced Professional (COSMOSWORK 2008 SP2.1)
Note: loading level for all sample is 54.25 N
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Comparison of FE model predictions and test data
Flexural creep
Primary Secondary Tertiary
Creep measured in Forintek
Expanded honeycomb core and HB skin. Sample span in y direction
Expanded honeycomb core and HB skin. Sample span in x direction
FE model predictions
FE model predictions
Note: loading level for all sample is 54.25 N
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Comparison of FE model predictions and test data
Bookshelf under bending
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Comparison of FE model predictions and test data
Flexural fatigue
FE model predictions
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ResultsInfluence of shelling ratio and cell size
Gxz of pane with 25.4 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Gxz of pane with 12.7 mm size cell
Gxz of pane with 25.4 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Gxz of pane with 12.7 mm size cell
Gxz of pane with 25.4 mm size cell
Gyz of pane with 25.4 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Gxz of pane with 12.7 mm size cell
Gyz of pane with 12.7 mm size cell
Gxz of pane with 25.4 mm size cell
Gyz of pane with 25.4 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Pane with 12.7 mm size cell
Pane with 12.7 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Ex of pane with 12.7 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Ex of pane with 12.7 mm size cell
Ex of pane with 25.4 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Ex of pane with 12.7 mm size cell
Ex of pane with 25.4 mm size cell
Ey of pane with 25.4 mm size cell
Note: all panels are made from expanded core and HB skins
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ResultsInfluence of shelling ratio and cell size
Core cell size(mm)
Web thickness(mm)
Ez
(MPa)Ey
(MPa)Gyz (MPa)
Gxy
(MPa)
15.9 0.29 10.06 644.76 4.72 228.55
20.3 0.37 10.07 645.08 4.86 228.64
Note: both panels are made from 26 mm thick expanded core and 3 mm thick HB skins and have the same core density
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ResultsInfluence of shelling ratio and cell size
Core density(Kg/m3)
Web thickness(mm)
Ez
(MPa)Ex
(MPa)Gxz (MPa)
Gxy
(MPa)
11.53 0.15 2.68 642.85 2.81 218.77
22.01 0.29 5.05 644.74 5.31 218.61
Note: both panels are made from 26 mm thick expanded core and 3 mm thick HB skins and have the same cell size.
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ResultsInfluence of shelling ratio and cell size
Aluminium panel. 38 mm cell size, 30 kg/m3 core density,1.210-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size
38 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
Aluminium panel. 38 mm cell size, 30 kg/m3 core density,1.210-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size
38 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size
38 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
32 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size
38 mm cell size, 15 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
32 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size
38 mm cell size, 15 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
32 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 8 kg/m3 core density,1.210-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size
38 mm cell size, 15 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
32 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 8 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 10 kg/m3 core density,1.310-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size
32 mm cell size, 10 kg/m3 core density,1.210-
6 kg/mm2 weight, longer panel
38 mm cell size, 15 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
32 mm cell size, 10 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 8 kg/m3 core density,1.210-6 kg/mm2 weight
38 mm cell size, 10 kg/m3core density,1.310-6 kg/mm2 weight
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ResultsInfluence of shelling ratio and cell size on flexural creep
Shelling ratio is 2
Shelling ratio is 4
Shelling ratio is 9
Shelling ratio is 12
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ResultsInfluence of core structure on the stiffness of
sandwich panel
Core type Ex (MPa)
Ey(MPa)
Ez(MPa)
Gxz (MPa)
Gyz(MPa)
Gxy(MPa)
Expanded honeycomb core
644.74 642.98 5.05 5.31 2.52 218.61
Corrugated honeycomb core
669.24 641.61 6.67 12.19 1.37 217.92
Note: sandwich panel with 3 mm thick HB skin and 26 mm thick core. All core densities are 22.01Kg/m3
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ResultsInfluence of core structure on the stiffness of
sandwich panel
Core type Ex (MPa)
Ey(MPa)
Ez(MPa)
Gxz (MPa)
Gyz(MPa)
Gxy(MPa)
Expanded honeycomb core
644.74 642.98 5.05 5.31 2.52 218.61
Corrugated honeycomb core
669.24 641.61 6.67 12.19 1.37 217.92
Note: sandwich panel with 3 mm thick HB skin and 26 mm thick core. All core densities are 22.01Kg/m3
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ResultsInfluence of core structure on the stiffness of
sandwich panel
Type of skin material
Ez(MPa)
Ey(MPa)
Gyz(MPa)
Gxy(MPa)
HB 8.05 641.78 4.58 227.46
MDF 8.03 388.88 4.56 137.78
PL 6.57 235.5 3.9 11.7
Note: sandwich panel with 3 mm thick skin and 26 mm thick core. All core densities are 22.01Kg/m3
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ResultsInfluence of core structure on the stiffness of
sandwich panel
Type of skin material
Ez(MPa)
Ey(MPa)
Gyz(MPa)
Gxy(MPa)
HB 8.05 641.78 4.58 227.46
MDF 8.03 388.88 4.56 137.78
PL 6.57 235.5 3.9 11.7
Note: Sandwich panel with 3 mm thick skin and 26 mm thick core. All core densities are 22.01Kg/m3
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ResultsInfluence of core structure on flexural creep of
sandwich panel
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ResultInfluence of skin type on flexural creep of
sandwich panel
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ResultsInfluence of cell size on flexural creep of sandwich
panel
15.9 mm cell size
31.8 mm cell size
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ResultsInfluence of curve degree and loading direction on
the bending stiffness of curved panel
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ResultsInfluence of core structure and loading direction on
the bending stiffness of curved panel
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ResultsInfluence of honeycomb core cell size on the
flexural fatigue of sandwich panel
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ResultsInfluence of degree of curve on the impact energy
of curved sandwich panel
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ResultsInfluence of degree of curve and impact orientation on
the impact energy of curved sandwich panel
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ResultsInfluence of rail width of shelf on the ratio of
bending force to deflection
Shelf with rail edge
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ResultsInfluence of stile width of shelf on the ratio of
bending force to deflection
Shelf with rail edgeShelf with rail edge
Shelf with stile edge
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ResultsInfluence of stile and rail width of shelf on the
ratio of bending force to deflection
Shelling ratio is 2.8
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ResultsInfluence of stile and rail width of shelf on the
ratio of bending force to deflection
Shelling ratio is 10.7
Shelling ratio is 2.8
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ResultsPrimary flexural creep of shelf with different size of
rail under uniform loading
65 mm wide rail
71 mm wide rail
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ResultsPrimary flexural creep of shelf with different size of
rail under uniform loading
Note: All panels have 32 mm thick core and 3 mm thick skin
250 mm wide rail65 mm wide rail
71 mm wide rail
38 mm wide rail
10 mm wide rail
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ResultsPrimary flexural creep of shelf with different size of
rail under uniform loading
Note: All panels have 32 mm thick core and 3 mm thick skin
250 mm wide rail65 mm wide rail
71 mm wide rail
38 mm wide rail
10 mm wide rail
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ResultsPrimary flexural creep of shelf with different
shelling ratio and 65 mm wide rail under uniform loading
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Conclusions• Finite element (FE) models for straight and curved sandwich panels
made from Kraft paper honeycomb core and wood composite skins were developed for predicting panels’ stiffness under compression, shear force, flexural loading, creep, fatigue and impact energy. The predicted Ex. Ey, Ez, Gxz, Gyz and primary flexural creep from the FE models were in good agreement with the respective experimental results. The predicted fatigue, impact and bending behavior of straight and curved sandwich panel from these initial FE models need to be calibrated by respective experiments.
• The influences of panel’s curve degree, loading direction, core shape, core cell size, core thickness, skin thickness and skin type on these behaviors were evaluated using these developed FE models. Some key points of optimization of these honeycomb core sandwich panels (e.g. shelling ratio, core shape, core density, core orientation and cell size, curved degree and orientation, etc) were found according to these evaluations.
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Conclusions• The FE models for bending and creep of bookshelves with edging
supports were developed too. The predictions from these FE models for sandwich panel four-point bending load were verified against test results. The influence of edging support size (rail and stile width) on the bending stiffness of shelf were studied using these FE models and the results indicated that bending stiffness is more sensitive to stile edgings of the shelf and shelling ratio than rail edgings. FE models for shelf under uniform flexural loading and creep need to be calibrated by further tests and the predicted results need to be confirmed by further experiments.
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Acknowledgement
NRCan-Value to wood program for financial support
FPinnovations-Forintek division in Quebec city and Pof. Greg Smith and his group in the University of British Columbia and for their cooperation and assistances