Madrid, September 2016

ADDITIVE MANUFACTURING

HOT BONDED INSERTS IN SANDWICH

STRUCTURES

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Marta García-Cosío

Juan Miguel González

Jeroen Vermeulen

Christian Rossmann Jannis Kranz

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Traditional Hot bonded insert

• Description of the piece • Manufacturing process

• How it is sized • Opportunities for mass saving

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Study case

• CFRP sandwich with Al honeycomb

• Titanium block insert

• thermoelastic stresses

• Mechanical Loads:

Table 1. Load cases used in the mechanical analysis Load Case Fz (N) Fy (N) Fx (N) Mx (Nm) My (Nm) Mz (Nm)

LC-1 5112 52697 128095 1327 0 734

LC-2 1889 37774 85488 3386 0 557

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Topologic optimization

mass reduction: 70%

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Thermoelastic stresses

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Shape optimization…

looking to improve stress distribution

Fig. 1 Original

Fig. 2 V02-OPT01

Fig. 3 Circle V05-02

Fig. 4 Gothic V06-02

Fig. 5 Butterfly V04-05

Fig. 6 Butterfly V04-03

mass reduction: 65%

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Manufacturing constrains

• Part Orientation • Overhangs • Supports • Powder removal • Residual thermal

stresses Distortions

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New design

• Manufacturing position and angles

• Holes for powder removal

• Struts to improve honeycomb connection

• Overthickness milling operation needed

mass reduction: 62%

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Lattice Structure…

To reduce distortions and avoid post machined operations

• Powder Removal

• Minimum Mass

• Structural validation

Cell dimensions Diameter of bars

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Lattice Radius in knot

• Using the minimum radius to save mass • Admissible stress levels at Knot

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New design with Lattice Lattice integration in the design,

meeting manufacturing criteria

65% of mass reduction

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Mechanical analysis validation

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Manufacturing and Verification

1. Manufacturing 2. Heat treatment 3. Sandblast 4. Cutting from built plate 5. Surface Post-machining 6. Threads milling

• Dimensional verification • Mass verification

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Conclusions and Next steps

Mass optimization & improvements in mechanical and thermoelastic behavior

seems to be a good approach…

TO BE VALIDATED BY TEST

And then, what about…

Improving bonding surface by means of pins?

Using different materials as steel or CFRP?

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Thank you