Core, Structure, Design Research with Sandwich Panels Prof. Dr.-Ing. Jörg Lange Institut für Stahlbau und Werkstoffmechanik, TU Darmstadt, Germany 1
Core Made of Corrugated Cardboard 2 picture: A. von der Heyden
Introduction Problems of common core materials: Petroleum-based Production is energy consumptive Recycling difficult and expensive Disposal pollutes the environment Ecological core material for sandwich panels has to be found Corrugated Cardboard? Source: polyurethan.isopol.de Source: cafol.my-icg.de Source: www.ybj-print.com Source: commons.wikimedia.org 3
Experimental Assessment Cardboard is considered to be orthotropic Orthotropy due to geometry of corrugations and due to fibre orientation in paper Tests conducted: Compression tests Tensile test Shear tests Bending tests on sandwich beams Thermal conductivity in different directions Controlled climate 20 C, 65 % RH 4
Summary Corrugated cardboard Polyurethane foam Mineral wool Density in kg/m³ 100 to 140 35 to 45 90 to 150 Young s modulus in N/mm² Shear modulus in N/mm² Compressive strength in N/mm² Thermal conductivity in W/(m K) 3 to 450 2 to 6 3 to 15 5 to 200 2 to 5 3 to 15 0.08 to 1,4 0.1 to 0.15 0.05 to 0.15 0.04 to 0.09 0.02 to 0.03 0.03 to 0.05 Corrugated cardboard with regard to bearing properties suitable for sandwich panels in building industry Corrugated cardboard has many advantages in respect of ecological issues compared to common core materials 5
Diaphragm Action of Sandwich Panels 6
Diaphragm Action of Sandwich Panels Experimental Assessment 7 picture: Ch. Kunkel
4,05 m HEB 140 HEB 140 Experimental Assessment Experimental Set-Up for the Diaphragm Action Tests 2,86 m D HEB 260 View A Sandwich Panel Square tube 40x40 (4 mm) B A HEB 260 HEB 140 F C A HEB 260 8 picture: Ch. Kunkel
Load in kn Experimental Assessment Results of the Diaphragm Action Tests 20 Diaphragm action (Wall panels d c = 100 mm - 4 x 2,86 m) 18 16 14 12 10 8 6 Wall panel 100 mm Type I - Test 1 Wall panel 100 mm Wall Type panel I - Test 100 1 mm Type I - Test 2 Wall panel 100 mm - Hook-and-Loop-Tape - Type Wall I panel - Test 1 100 mm Wall Type panel I - Test 100 2 mm - Hook-and-Loop-Tape - Type I - Test 2 hook-and- }loop-tape 4 2 0 0 5 10 15 20 25 30 35 Displacement of the rig in mm 9 picture: Ch. Kunkel
Experimental Assessment Findings of the Diaphragm Action Tests The shear diaphragm action depends on the stiffness of the connection between panels and substructure. The assembly of the fastenings is accountable for the maximum bearing capacity. The connections of the panels via the longitudinal joint participate in the shear diaphragm action. How does the longitudinal joint transfer the load between the panels? 10
Experimental Assessment Experimental Set-Up for the Longitudinal Joint Tests Load steps of the horizontal force: 0,5 kn 1,0 kn 1,5 kn 2,0 kn 11 picture: Ch. Kunkel
Experimental Assessment Results of the Longitudinal Joint Tests Longitudinal joint with standard sealing tape Sealing tape 12 picture: Ch. Kunkel
Experimental Assessment Strengthening of the Longitudinal Joint Hook-and-loop-tape (glued with one component polyurethane prepolymer adhesive) 13 picture: Ch. Kunkel
Experimental Assessment Results of the Longitudinal Joint Tests Longitudinal joint with hook-and-loop-tape Hook-and-loop-tape instead of sealing tape 14 picture: Ch. Kunkel
Summary Longitudinal joints effect the bearing capacity of the diaphragm action Integration of the joint in the calculation model Improvement by strengthening the joint by hook-and-loop-tape Maximum load up to twice as high 15
Interaction N pull-over shear V pull-out ETA 16 picture: K. Kilian
Interaction - Tests 17 picture: K. Kilian
Interaction Recommendation (Bracing) Bearing capacity of the sandwich panel if V E,d V R,I,d 0,25 N E,d N R,I,d 1,0 N only if V Ed is cyclic or deflections are restricted (3 mm) V 0,25 < V E,d V R,I,d 1,00 N E,d N R,I,d + V E,d V R,I,d 1,0 N R,I,d V R,I,d Design value for pull-over Design value for shear Bearing capacity of supporting structure according to for steel: EN 1993-1-3:2006 for aluminum: EN 1999-1-4:2007 for timber: EN 1995-1-1:2004+A1:2008 N R,II,d V R,II,d Design value of pull-out Design value for shear 18 picture: K. Kilian
Curved Panels 19 picture: St. Schäfer
Curved Panels 20 picture: St. Schäfer
Curved Panels 21
Curved Panels 22
Core, Structure, Design Research with Sandwich Panels Prof. Dr.-Ing. Jörg Lange Institut für Stahlbau und Werkstoffmechanik, TU Darmstadt, Germany 23