leichtbaukonstruktionen - eth z€¦ · courtesy of dr. markus zogg, inspire ics paolo ermanni...
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Paolo Ermanni23. September 2015
Vorlesung 151-3207-00L Leichtbau, HS 2015
Leichtbaukonstruktionen
23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 1
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§ Allgemeines über den Entwicklungsprozess
§ Leichtbaustrategien
§ Auslegungskriterien
Leitfaden
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Leichtbaukonstruktionen
Optimale GestaltEine möglichst gleichmässigeBeanspruchung in möglichst allenBereichen der Bauteile
Sicherheit gegen VersagenEine unter allen Betriebs-bedingungen ausreichende Sicherheit gegen Versagen infolge Bruch, Fliessen, Knicken, Beulen, zu grosse Deformation, Ermüdung etc.
WirtschaftlichkeitGeeignetes Material für das Bauteilmöglichst kostengünstige Fertigung
Die Bauteilgestalt ist so zu wählen, dass optimale
Gesamtlösungen resultieren
23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 3
|| 9/23/15Gerald Kress 4
“Function and form are intimately related to one another.
The function describes what the purpose of a technical object is;; the form or structure describes how this product will do it.”
Ulman, D.G., The Mechanical Design Process, vol. 2, McGraw-Hill, New York (1997)
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Werkstoffwahl: Stahl, Aluminium, Titanium, FV-Kunststoffe…..
Topologie Gestaltung Abmessungen
Strukturmerkmale
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Automated structural analysis process
Quelle: Ch. Ledermann, Parametric Associative CAE Methods In Preliminary Aircraft Design, Diss. ETH Nr. 16778, 2006 23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 6
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Flügel General Arrangement
Quelle: M.C. Niu, Airframe Structural Design, Conmilit Press, 199123.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 7
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Vergleichsspannungen (von Mises)
Quelle: Ch. Ledermann, Parametric Associative CAE Methods In Preliminary Aircraft Design, Diss. ETH Nr. 16778, 2006
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Spannungsverteilung in der Haut nach der Optimierung
Quelle: Ch. Ledermann, Parametric Associative CAE Methods In Preliminary Aircraft Design, Diss. ETH Nr. 16778, 2006
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Optimierte Dickeverteilung
Quelle: Ch. Ledermann, Parametric Associative CAE Methods In Preliminary Aircraft Design, Diss. ETH Nr. 16778, 2006
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Optimization results
Best individual of initial generation Best individual after 60 generations
Fitness plot Design objective: mass
Quelle: Ch. Ledermann, Parametric Associative CAE Methods In Preliminary Aircraft Design, Diss. ETH Nr. 16778, 2006
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Generische Produktentwicklung
Ledermann, Christoph, Parametric associative CAE methods in preliminary aircraft design, Diss. ETH Zurich Nr. 16778, Zürich, 2006
Conceptualdesign
Embodimentdesign Detail design
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§ Allgemeines über den Entwicklungsprozess
§ Leichtbaustrategien
§ Material-Substitution
§ Formleichtbau
§ Konzeptleichtbau (Bauweisen)
§ Auslegungskriterien
Leitfaden
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Show case: Sample dimensions
aluminum plate (reference):• length: l = 200 mm• width: w = 50 mm• thickness: talu = 4 mm• mass: malu = ρalu ⋅ l ⋅ w ⋅ talu = 108.0 g
plates made of alternative materials:• length: l = 200 mm• width: w = 50 mm• thickness: talt = varied to reach requested
performance• mass: malt = ρalt ⋅ l ⋅ w ⋅ talt
Courtesy of Dr. Markus Zogg, Inspire ICS
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Show case: loads
§ Weight comparison of monolithic plates made of different materials all with same length and width
§ Thickness designed for same…§ tensile stiffness§ tensile strength§ compression stiffness§ compression strength§ bending stiffness§ bending strength
Courtesy of Dr. Markus Zogg, Inspire ICS
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Lightweight material parameters
§ Reference (Aluminum alloy)
§ Key lightweight material parameters→→ E0 = 73 GPa;; σσmax-0 = 400 MPa;; ρρ0 = 2.7 ⋅⋅ 10³ kg/m³
2 x specific stiffness2 x specific stiffness > same specific strength and density→→ Estiff = 2 ⋅⋅ E0;; σσmax-stiff = σσmax-0;; ρρstiff = ρρ0
2 x specific strength2 x specific strength > same specific stiffness and density →→ Estrength = E0;; σσmax-strength = 2 ⋅⋅ σσmax-0;; ρρstrength = ρρ0
0.5 x density0.5 x density > same specific stiffness and specific strength →→ Edensity = 0.5 ⋅⋅ E0;; σσmax-density = 0.5 ⋅⋅ σσmax-0;; ρρdensity = 0.5 ⋅⋅ ρρ0
Courtesy of Dr. Markus Zogg, Inspire ICS
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Lightweight material parameters
reference
2 x specific stiffness
2 x specific strength
0.5 x density
Courtesy of Dr. Markus Zogg, Inspire ICS23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 17
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Lightweight material parameters
Courtesy of Dr. Markus Zogg, Inspire ICS 23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 18
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Lightweight material parameters
Courtesy of Dr. Markus Zogg, Inspire ICS 23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 19
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Lightweight material parameters
Courtesy of Dr. Markus Zogg, Inspire ICS 23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 20
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Material comparison
6401917.9steel - V2A
aluminum alloy (reference)
E-GF / Epoxy
CF-HT / Epoxy
CF-HM / Epoxy
CF-UHM / Epoxy
titanium (TiAl6 V4 F89)
densityρ
[103 kg/m³] quasi-isotropic
strengthσmax [106 N/m²]
quasi-isotropic
modulusE [109 N/m²]
400732.7
8901204.5
34118.91.88
40843.61.53
33566.61.55
22385.61.55source: Markus Zogg;; Neue Wege zum Recycling von faserverstärkten Kunststoffen;; Diss 11'946, ETH Zürich, 1997
properties
materials
laminates calculated with 50 %vol fiber contentCourtesy of Dr. Markus Zogg, Inspire ICS
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Material weight saving potential
GF/EP-qi
CF-UHM/EP-qi
CF-HM/EP-qi
CF-HT/EP-qisteelaluminum
titanium
Courtesy of Dr. Markus Zogg, Inspire ICS
23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 22
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Material weight saving potential
Courtesy of Dr. Markus Zogg, Inspire ICS 23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 23
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Material weight saving potential
Courtesy of Dr. Markus Zogg, Inspire ICS
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Material weight saving potential
GF/EP-qi
CF-UHM/EP-qi
CF-HM/EP-qi
CF-HT/EP-qisteelaluminum
titaniumlimits
of metalslimits
of metals
Courtesy of Dr. Markus Zogg, Inspire ICS
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Materials to be compared: Material orientation
6401917.9steel - V2A
aluminum alloy (reference)
E-GF / Epoxy
CF-HT / Epoxy
CF-HM / Epoxy
CF-UHM / Epoxy
titanium (TiAl6 V4 F89)
densityρ
[103 kg/m³] uni-directional
quasi-isotropic
strengthσmax [106 N/m²]
uni-directional
quasi-isotropic
modulusE [109 N/m²]
400732.7
8901204.5
34118.91.88
40843.61.53
33566.61.55
22385.61.55source: Markus Zogg;; Neue Wege zum Recycling von faserverstärkten Kunststoffen;; Diss 11'946, ETH Zürich, 1997
properties
materials
laminates calculated with 50 %vol fiber content
-
-
-
38.0
113.0
183.8
242.2
-
-
-
1'015
1'219
927
632
Courtesy of Dr. Markus Zogg, Inspire ICS
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Material weight saving potential
GF/EP-qi
CF-UHM/EP-qi
CF-HM/EP-qi
CF-HT/EP-qisteelaluminum
titanium
GF/EP-UD
CF-HT/EP-UD
CF-HM/EP-UD
CF-UHM/EP-UD
Courtesy of Dr. Markus Zogg, Inspire ICS
23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 27
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Material weight saving potential
quasi-isotropicunidirectional
Courtesy of Dr. Markus Zogg, Inspire ICS
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Material weight saving potential
quasi-isotropicunidirectional
Courtesy of Dr. Markus Zogg, Inspire ICS
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§ Allgemeines über den Entwicklungsprozess
§ Leichtbaustrategien
§ Material-Substitution
§ Formleichtbau
§ Konzeptleichtbau (Bauweisen)
§ Auslegungskriterien
Leitfaden
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Direct loadintroduction
Maximization of themoment of inertia
Ribbing of structures
Application of curvedstructures and panelsheets
Adoption, wherereasonable, ofintegral constructions
Selective localreinforcement in themain load directions
Some design rules for lightweight structures (according to B. Kleint)
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Direct load-introduction
Directly introduce loads in the main structure
Avoid load deviation
Distribute loads over large surfaces
Locally support load-introduction
Source: B. Klein, Leichtbaukonstruktion, Berechnungsgrundlage und Gestaltung, 8. Auflage Vieweg und Teubner, 2009
Unfavourable Better Comments
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Maximization of the moment of inertia
Utilization of thin-walled profiles with
light supporting cores
Unfavourable Better Comments
Source: B. Klein, Leichtbaukonstruktion, Berechnungsgrundlage und Gestaltung, 8. Auflage Vieweg und Teubner, 2009
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Ribbing of structures
Lattice panel sheet Studded panel sheet
Unfavourable Better Comments
Utilization of thin-walled profiles
Source: B. Klein, Leichtbaukonstruktion, Berechnungsgrundlage und Gestaltung, 8. Auflage Vieweg und Teubner, 2009
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Application of curved structures and panel sheets
Unfavourable Better Comments
Curved shapes show an increase of the critical buckling loads compared to
flat ones
In curved plates and panels the
resistance against deflection and snap-through is increased
Source: B. Klein, Leichtbaukonstruktion, Berechnungsgrundlage und Gestaltung, 8. Auflage Vieweg und Teubner, 2009
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Adoption of integral constructions
Unfavourable Better Comments
Source: B. Klein, Leichtbaukonstruktion, Berechnungsgrundlage und Gestaltung, 8. Auflage Vieweg und Teubner, 2009
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Selective local reinforcement in main load directions
Unfavourable Better Comments
Corrugations increase panel
stability
Orient fibres in load direction
Source: B. Klein, Leichtbaukonstruktion, Berechnungsgrundlage und Gestaltung, 8. Auflage Vieweg und Teubner, 2009
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Example: Wing structure
Source: M.C. Niu, Airframe Structural Design, Conmilit Press, 1991 23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 38
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§ Allgemeines über den Entwicklungsprozess
§ Leichtbaustrategien
§ Material-Substitution
§ Formleichtbau
§ Konzeptleichtbau (Bauweisen)
§ Auslegungskriterien
Leitfaden
23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 39
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§ Positive§ Combination of different materials is possible§ „Simple“ Recycling and Repair
§ Negative§ Weight§ Prone to corrosion
Structural components can be realized by assembling together single structural elements
Source: Eurocopter23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 40
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Integral construction: Single structural elements are co-bonded or co-cured together
Integral skin tear straps
Viable Repair Plans
Co-cured hat section stringers
Bolted frames
Fabric surface plies
Source: Boeing
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Composites in der A380
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§ Metallic Structures:§ Glare Technologies§ Extrusion Profiles in
conjunction with advanced welding Techniques
§ Composite Structures§ Tape-laying processes§ Preforming technologies in
conjunction with LCM-Processes (RTM, RFI)
§ Pultrusion technologies for Stringers and Beams
Technological Trends at Airbus (cont.)
[4] Neil Harris, The A380, Leader on Manufacturing technology, Farnborough 20th/21st July 2004
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l Large parts and complex shapesl Optimum ply distribution l First application on A380
(A380 rear section)
Solutions for complex fibre elements
[4] Neil Harris, The A380, Leader on Manufacturing technology, Farnborough 20th/21st July 2004
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Boeing 787: Airframe Material Selection:
Carbon laminate
Carbon sandwich
Fiberglass
Aluminum
Aluminum/steel/titanium pylons
53%
Source: Boeing
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Sandwich constructions are a good example for lightweightstructural elements
Laminate
Adhesive layer
Honeycomb
Adhesive layer
Laminate
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Sandwich: Typical core materials
Stegkern Wellblechkern Wabenkern
Massiv- oder Schaumstoffkern
gelochter Massiv- oder Schaumstoffkern !
Source: Dr. Habil. Alois Starlinger, Handouts of the lecture “Bemessen von Sandwichbauteilen”
HoneycombCorrugated core
Cellular materials (foams) or balsa
Web
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Load-carrying behavior of sandwich structures
zN
QMb
xσσN σσb ττ xz
h
zN
QMb
xσσN σσb ττ xz
STRESS-DISTRIBUTION IN NON-CONNECTED LAYERS
Source: Dr. Habil. Alois Starlinger, Handouts of the lecture “Bemessen von Sandwichbauteilen”
STRESS-DISTRIBUTION IN CONNECTED LAYERS
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Learning from nature§ Lightweight structures § Lightweight structures made of fiber
reinforced polymers allow high performance race cars with an extraordinary safety level
lightweightmaterials
integration of functions
material orientation
material arrangement
Courtesy of Dr. Markus Zogg, Inspire ICS
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Learning from nature§ Technical structures § tree-trunks carry the high loads of the tree
tops and can reach an age of several 100 years
lightweightmaterials
integration of functions
material orientation
material arrangement
Courtesy of Dr. Markus Zogg, Inspire ICS
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lightweightmaterials
integration of functions
materialorientation
material arrangement
nature
Learning from nature
Courtesy of Dr. Markus Zogg, Inspire ICS
§ Compared to natural structures, technical structures are (often) made of materials, with superior mechanical performance.
§ The excellent lightweight performance of natural structures is reached by:§ the designed anisotropy in the
material performance§ the optimal placement of the material
in structures with high geometrical complexity
§ integration of many functions into the structure
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Integration of functionsExample: Lightweight structure in transportation
acoustic treatment
interior surfacesupport for ... venting
hosehousing for ...
structure damping treatment
pipes for fluids
exterior surface
wires
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support for ...
venting hose
housing for ...
interior surface
acoustic treatment
structurewires damping treatment
pipes for fluids
exterior surface
1 multifunctional component
Integration of functionsExample: Lightweight structure in transportation
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transportation structure with add-on functionstransportation structure with add-on functions
multiple suppliers
multiple designs
multiple sets of tools
multiple part references
transportation structure with integrated functions
one supplier
one design
one set of tools
one part references
Integration of functionsExample: Lightweight structure in transportation
opportunity to save weight and costs23.09.15PAOLO ERMANNI - 151-3207-HS2015-K2-LEICHBAUKONSTRUKTIONEN 54
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§ BASIS: Lotus Evora§ CHALLENGE: The wheelbase has to be
extended by 30 cm in order to accommodate all the components
§ SOLUTION: rear end (everything behind the passenger compartment) made out of RFP § new rear structure made out of CFRP
sandwich§ new rear bodywork, partly as a sandwich
§ Training for 30 students on the example of a four-seat electric-powered sport car
Functions Integration – Example SunCar2011
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§ Built-in "Fail-Safe behavior" in the bodywork§ In the event of a crash, the bodywork can not break and no sharp-edged fragments
Functions Integration: Example SunCar2011
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§ Solar cells integrated in the vehicle roof and the hatchback§ Solar cells are integrated directly into the body
Functions Integration: Example SunCar2011
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§ Built-in thermal insulation of the batteries in the sandwich structure of the chassis§ The foam core has structural functions and
also serves to isolate the batteries§ Electrical conductors have been partially
integrated into the composite structure § Instead of additional cables in channels
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Functions Integration: Example SunCar2011
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Functions Integration: Example SunCar2011
§ Integrated heating/cooling circuits in the composite structures have been object of a bachelor thesis
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