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A Novel Full-scale Validation ofThermal Degradation of Polymer
Foam Cored Sandwich Structures
R.K. Fruehmann, J.M. Dulieu-Barton, O.T. Thomsen15.02. 2011
2
Outline• Background
• Review of design brief
• Design for mechanical boundary conditions
• Thermal gradient measurement
• Validation tests
• Conclusions
5
Background
Face sheet displacement at different loads Force / mid-span displacement results from3 different models
(Frostig et al. 2004)
• High-order sandwich panel theory (HSAPT) predicts strongly non-linear interactions between mechanical and thermal loads.
• Strongly non-linear and unstable load response and limit point behaviour in some cases.• Load response strongly sensitive to boundary conditions.• Experimental validation is required.
6
Design Brief• Mechanical
1. Simply supported
2. Lower corner fixed – free to rotate
3. Fully clamped
• Thermal
1. Uniform across width
2. Linear through thickness
• Measurement
1. Non-contact (DIC & IR)
Condition 1
Condition 2
Condition 3
12
Design – General arrangement
Radiator
Insulation
Mirror to monitor topface sheet
Mirror to monitor bottomface sheet
20
Validation tests• Specimen dimensions:
– 450 x 50 x 27 mm
– 1 mm thick aluminium face sheets
– 25 mm thick H100 PVC foam
• Temperature profile across the width and through the thickness
• Recorded the deformations at the mid-span using DIC
26
Mid-span deformation
• Careful consideration of face sheet failure loads to avoid indentation failure preceding geometric non-linearity.
27
Conclusions
• Thermal and mechanical boundary conditions have been achieved.
• Mid-span deflections correspond qualitatively with model predictions for the simply supported case.
28
Future challenges• Optimise specimen configuration (material and
geometry) to remain in the elastic region.
• Obtain DIC data from the thin face sheets.
• Obtain DIC data below the roller during indentation.