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Ultrasonic Joining (U-Joining) of Metal-Composites Hybrid Joints E.E. Feistauer a,1,2, T. Ebel b,3, J.F. dos Santos a,1, S.T. Amancio-Filho a,1,2

Institute of Materials Research, a Materials Mechanics, 1 Solid State Joining Processes, 2 Advanced Polymer-Metal Hybrid Structures / b Metallic Biomaterials, 3Materials Design and Characterisation

Helmholtz-Zentrum Geesthacht • Max-Planck-Straße 1 • 21502 Geesthacht • Germany • Phone /Fax: +49 (0)4152 87-2066 / 2033 • www.hzg.de Contact: Eduardo E. Feistauer (technical requests), eduardo.feistauer@hzg.de / Prof. Dr. -Ing. Sergio Amancio (group leader), sergio.amancio@hzg.de

A new direct-assembly joining technology

Results Microstructural features

Summary

Heat development

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Local mechanical properties

Global mechanical properties

U-Joining: Metal Injection Molding (MIMStruct) + Ultrasonic Welding Environmental friendly Energy efficient Faster in comparison to the state-of-the-art Localized heat development No solvent, adhesive or additional materials

Joining by mechanical interlocking due to the surface 3D reinforcement (metallic pins) and adhesion forces (polymer consolidation)

Figure 3: Schematically representation of the U-Joining process. (1) Positioning of joining parts, (2) Application of

ultrasonic vibration and axial force, (3) Softening of polymer by frictional heat at the interface and onset of pin insertion, (4)

Polymer consolidation and (5) End of the process and sonotrode retraction.

Figure 4: Process phases. P1 - Accomplishment of contact between MIMStruct

pins and composite, P2 - Coulomb friction and unsteady state viscous

dissipation, P3 - Steady state viscous dissipation, P4 - Complete pins’

penetration and creation of adhesive forces at the joint interface, and P5 -

Joint consolidation.

Ultrasonic Joining (U-Joining, pat. applic. EU 15163163.7 ) Phases of the process

GF-PEI

MIMStruct 4 Pins

TMAZ

GFPEI

Overlap area: 13 x 15mm MIMStruct thickness: 2.85 GFPEI thickness: 6.35 4 pins

Overlap area: 19 x 15mm MIMStruct thickness: 2.85 GFPEI thickness: 6.35 6 pins 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

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Pin-less reference 4 Pins MIMStruct 6 Pins MIMStruct

Lap

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ce [N

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Displacement [mm]

Principles of the process

The U-Joining concept

A new approach to manufacture future damage-tolerant and crash-resistant lightweight alloy/composite hybrid structures has been introduced.

Figure 2: MIMStruct manufacture route. The manufacture is

based on the metal injection molding technology.

Figure 5: Cross-sectional view of a 4 pins joints.

Figure 11: Customized-lap shear tensile testing . 0 2 4 6 8 10 12 14 16 18150

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Max. temp. R1 Max. temp. R2

Figure 9: Curves of maximum temperature obtained by infrared thermography.

Figure 7: Formation of micromechanical interlocking at the MIMStruct (3) and pins (4) surface due to the opened porous.

Figure 8: The molten PEI expelled during the process fills the pin cavities (1). No visual microstructural changes in the MIMStruct part (2). Residual porosity = 4.4 ± 0.7%.

Figure 12: Fracture surface of a 6-pins U-joint. The failure mechanism combines

shearing of the metallic pins and mixed cohesive-adhesive failure of the composite.

Figure 10: Microhardness maps for the 4 pins joints.

MIMStruct (EP 2 468 436 B1) production of 3d-structured parts

Figure 1: Potential application for the U-Joining are found in the automotive, aerospace and infrastructure sectors.

Preliminary assessment resulted in fast joining cycles (between 1.3 and 1.7 seconds)

The 3D reinforcement of MIMStruct parts was successfully inserted in the composite by means of ultrasonic energy

The thermal-mechanical processing does not changes the mechanical properties of the MIMstruct part

The hybrid joints showed improved lap shear strength and toughness in comparison to pin-less reference joints

Failure location

Potential application

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