COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Laboratory for Timber Constructions

Friction Welding of WoodCOST Action FP0904

Thermo-Hydro-Mechanical Wood Behaviour and Processing

Bernhard Stamm, dr ès sc. EPFL

IBOIS | EPFL | Lausanne

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

• Thermal modification of wood

• Formation of an adhesive contact layer

The welding process

20°C 400°C300°C

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Expulsion of softened material

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

The welding process

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Mécanismes d‘adhésion

a) Liaison chimique entre des atomes et des molécules

b) Liaison mécanique par imbrication dans les aspérités des surfaces

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Welded interface (Norway spruce)

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Influence of Moisture on the welding process

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Influence of Moisture on the welding process

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Influence of Moisture on the shear resistance

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Failure mechanisms

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Failure mechanisms

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

0

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150

200

250

300

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0.0

0.5

1.0

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3.0

0 100 200 300 400 500 600 700 800 900

Temperature [°C]

Shear Strength [MPa]

Time [s]

average shear strength

interfacial temperature progression

quadr. approximation of the interfacial shear strength

Evolution of interfacial shear strength

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Multilayered compounds

Crosswise welded boards forming a plywood beam (spruce)

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Potential fields of application:

laminar connections, prefabrication

Timber construction, furniture industry

Examples for aimed application :

Laminated wall & ceiling elements Parquet flooringPlywood made of boards

COST Action FP0904 Thermo-Hydro-Mechanical Wood Behaviour and Processing

Friction Welding of Wood, Bernhard Stamm

Thank you for your attention !