Optimization of geometry and core material of sandwich panels with metallic faces

Transcription

1 Optimization of Sandwich Panels Dipl.-Ing. Aneta Kurpiela Institute of Steel Construction and Material Mechanics Optimization of geometry and core material of sandwich panels with metallic faces

2 Introduction Study Studies of Civil Engineering at the Opole University of Technology (Poland) Exchange Programme for Students at the University of Applied Sciences Mainz (Germany) First contact with Sandwich Technology Studies of Civil Engineering at University of Applied Sciences Mainz Professional activities Work Experience in Engineering Office Research Assistant at the Institute for Sandwich Technology Mainz since Sept Research Assistant and Doctoral Thesis at the Technische Universität Darmstadt (Germany)

3 Content Background Aim of the optimization Theoretical optimization of mechanical properties Optimization of core material Optimization of metallic faces First tests of sandwich panels with lightly profiled faces

4 Optimization of Sandwich Panels Why? Possibility to save money and resources Lack of investigations into optimization of sandwich panels Possibility to get sandwich panels with better load bearing capacity Previous experience and observations during the mechanical tests Capability of the producers to create sandwich panels with defined properties

5 Research Project SandTweak is-mainz External source Realization September 2006 September 2009

6 Project partners SandTweak is-mainz

7 Aim of the Optimization of Sandwich Panels production costs load bearing capacity material costs production technology Aim of Optimization insulating properties ecological compatibility

8 Aim of the Optimization of Sandwich Panels production costs load bearing capacity material costs production technology Aim of Optimization insulating properties ecological compatibility

9 Main Works Investigation into Mechanical Properties of Sandwich Panels Optimization of Core Material - theoretical Optimization of Metal Faces - theoretical, experimental Optimization of Complete Sandwich Panel - in progress

10 Optimization of Core Materials Three most commonly used core materials of sandwich panels PUR MW PS G C =? f Cv =? E Cc =? f Cc =? E Ct =? f Ct =? Which strength and modulus values are needed to get an optimal core material?

11 Optimization of Metal Faces Different forms, geometries and thicknesses of metallic faces b P1 =? b P2 =? b R =? h R =? t f =? R eh =? Which combination of dimensions and yield strength of metal face are needed to get an optimal face geometry?

12 Optimization of Complete Sandwich Panel Which combination of the mechanical properties of the core and geometry of the faces - leads to high load bearing capacity (maximal spans)? - is possible to manufacture? - uses the material most economically?

13 Investigations into Mechanical Properties Complicated calculations

14 Investigations into Mechanical Properties Complicated calculations different statical systems roof panel wall panel

15 Investigations into Mechanical Properties Complicated calculations different statical systems different possible failure modes Wrinkling of metal face (σ w ) Shear failure of the core (f Cv ) Compressive failure of the core (f Cc )

16 Investigations into Mechanical Properties Complicated calculations different statical systems different possible failure modes special loads and load cases Temperature differences Summer load ΔT Summer Creeping of the core 25 C 80 C Winter load ΔT Winter Δ S ±0 C 20 C

17 Investigations into Mechanical Properties Complicated calculations different statical systems different possible failure modes special loads and load cases

18 Optimization of Core Materials 1 st Step Optimization of core material for panel with given geometry any existing panel with given geometry G C =? f Cv =? E C =? f Cc =? f Ct =? OPTIMUM concerning design

19 Optimization of Core Materials 1 st Step Optimization of core material for panel with given geometry Searching for: Mechanical properties from certain sets: G C G C1 ; G C2 E C E C1 ; E C1 f Cv f Cv1 ; f Cv2 f Cc f Cc1 ; f Cc2 Aiming at Requirements: 1. High load bearing capacity 2. High utilization factor of mechanical properties f Cv 100 % f Cc 100 % σ w = f(g C, E C ) 100 % w = f(g C ) 100 % OPTIMUM concerning design

20 Optimization of Core Materials 1 st Step Compressive strength f Cc in MPa Compressive strength f Cc in MPa Density in kg/m 3 Density in kg/m 3 PUR G C 1,9; 5,5 E Cc 1,0; 5,0 f Cc 0,06; 0,20 f Cv 0,085; 0, Determination of certain sets according to known material properties (possible to manufacture) 2. Determination of new combinations of mechanical properties new core materials

21 Optimization of Core Materials 1 st Step Calculations in optimization processes 1. Selection of an existing sandwich panel with given face geometry 2. Creation of new elements with the given face geometry and new core materials 3. Calculations of span widths for different statical systems and load cases for old panel (Point 1) and new panels (Point 2) 4. Comparison of results 5. Determination of the optimal core material from the defined sets

22 Optimization of Core Materials 1 st Step Results and conclusion Increasing the span width is possible but Wrinkling strength σ w is most relevant factor for limitation of span width of sandwich panel: Optimization of Metal Faces

23 Optimization of Metal Faces Walls Flat Corrugated profile Bead profile Micro-lined profile Ribbed profile Roofs Corrugated profile Ribbed profile Trapezoidal profile

24 Optimization of lightly profiled Metal Faces Walls Flat Corrugated profile Bead profile Micro-lined profile Ribbed profile Roofs Corrugated profile Ribbed profile Trapezoidal profile

25 Optimization of lightly profiled Metal Faces Walls Ribbed wall profile New analytical model for σ w!!! σx Evaluation of wrinkling strength σ w with consideration of - buckling theory - elastic bedding on the core σx td, BD EC, GC, νc

26 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength Analytical model based upon existing theory for flat faces σ = a E G E 3 w,flat C C F

27 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength Analytical model based upon existing theory for flat faces Additionally Consideration of the light-profiling - flat plate strips and stiffeners (ribs or crimps)

28 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength Analytical model based upon existing theory for flat faces Additionally Consideration of the light-profiling - flat plate strips and stiffeners (ribs or crimps) Consideration of yield strength of the metal faces R eh R eh

29 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength Analytical model based upon existing theory for flat faces Additionally Consideration of the light-profiling - flat plate strips and stiffeners (ribs or crimps) Consideration of yield strength of the metal faces R eh Consideration of tensile strength of the core f Ct R eh f Ct

30 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength Analytical model based upon existing theory for flat faces Additionally Consideration of the light-profiling - flat plate strips and stiffeners (ribs or crimps) Consideration of yield strength of the metal faces R eh Consideration of tensile strength of the core f Ct R eh f Ct

31 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength σ = w,ue,f Ct σw,ue π 1 1+ EC GC 500 f Ct σ w,i i σ w,ue = and w,i eh Ai 3 A σ 3 w,i = eff,i 2 tf 2 B K σ R 2

32 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength σ = w,ue,f Ct σw,ue π 1 1+ EC GC 500 f Ct σ A σ R w,i i σ w,ue = and w,i eh Ai Properties of metal faces 3 σ 3 w,i = eff,i 2 tf 2 B K 2

33 Optimization of lightly profiled Metal Faces Analytical model for assessment of the ideal wrinkling strength σ = w,ue,f Ct σw,ue π 1 1+ EC GC 500 f Ct Properties of core material + σ A σ R w,i i σ w,ue = and w,i eh Ai Properties of metal faces 3 σ 3 w,i = eff,i 2 tf 2 B K 2

34 Optimization of lightly profiled Metal Faces b P1 = b P2 b R = 4h R 400 hr = 0,5 mm Wrinkling strength in N/mm² hr = 1,0 mm hr = 1,5 mm hr = 2,0 mm hr = 2,5 mm hr = 3,0 mm t F = 0,5 mm R eh = 350 N/mm² E C = G C = 3,0 N/mm² Plate width b P1 =b P2 in mm

35 Optimization of Metal Faces - First Tests Tested panel faces: Steel ribbed profile, t F = 0,6 mm PUR panel thickness: 80 mm F Increasing the rib depth h R h R = 0,60 mm h R = 0,90 mm h R = 1,30 mm EN (2006), A.5. Wrinkling strength σ w =?

36 Optimization of Metal Faces - First Tests Tested panel faces: Steel ribbed profile, t F = 0,6 mm PUR panel thickness: 80 mm Panel type: Wall Face geometry: Ribbed profile Depth of the ribs h R Wrinkling strength σ w Increasing of wrinkling strength 0,60 mm 0,90 mm 1,30 mm 170,4 N/mm² - 188,5 N/mm² 10,6 % 208,2 N/mm² 22,2 %

37 Optimization of Metal Faces - First Tests Tested panel faces: Steel ribbed profile, t F = 0,6 mm PUR panel thickness: 80 mm Panel type: Wall Face geometry: Ribbed profile Wrinkling strength in N/mm² Calculation Test 0 0,0 1,0 2,0 3,0 4,0 Depth of the ribs h R in mm

38 Optimization of Sandwich Panel σ = w,ue,f Ct σw,ue π 1 1+ EC GC 500 f Ct Shear strength of the core (f Cv ) Wrinkling of metal face (σ w ) Compressive strength of the core (f Cc )

39 Optimization of Sandwich Panel Conclusion: Many possibilities for increasing the load bearing capacity - increase of the depth of the profiling h R - narrower placing of crimps (narrower plate widths b P ) - selection of optimal yield strength R eh of metal faces - selection of optimal f Ct ; f Cc ;f Cv of core material - selection of the optimal E C and G C of core material face geometry face material core material

40 Optimization of Sandwich Panel Conclusion: Many possibilities for increasing the load bearing capacity - increase of the depth of the profiling h R - narrower placing of crimps (narrower plate widths b P ) - selection of optimal yield strength R eh of metal faces - selection of optimal f Ct ; f Cc ;f Cv of core material - selection of the optimal E C and G C of core material Additionally - thickness of the core - thickness of the metal faces face geometry face material core material material volume material costs

41 Optimization of Sandwich Panel production costs load bearing capacity material costs production technology Aim of Optimization insulating properties ecological compatibility

42 Optimization of Sandwich Panel production costs load bearing capacity material costs production technology Aim of Optimization insulating properties ecological compatibility

43 Optimization of Sandwich Panel production costs load bearing capacity material costs production technology Aim of Optimization insulating properties ecological compatibility

44 Optimization of Sandwich Panel load bearing capacity material costs Optimization with mathematical methods Next step in the Optimization Project

45 Optimization of Sandwich Panels Dipl.-Ing. Aneta Kurpiela Institute of Steel Construction and Material Mechanics Thank you very much!