1. Madrid, September 2016
ADDITIVE MANUFACTURING
HOT BONDED INSERTS IN SANDWICH
STRUCTURES
Trusted Partner for your Digital Journey
Marta García-Cosío
Juan Miguel González
Jeroen Vermeulen
Christian Rossmann
Jannis Kranz

2. Trusted Partner for your Digital Journey
Traditional Hot bonded insert
• Description of the piece
• Manufacturing process
• How it is sized
• Opportunities for mass saving

3. Trusted Partner for your Digital Journey
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

4. Trusted Partner for your Digital Journey
Topologic optimization
mass reduction: 70%

5. Trusted Partner for your Digital Journey
Thermoelastic stresses

6. Trusted Partner for your Digital Journey
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%

7. Trusted Partner for your Digital Journey
Manufacturing constrains
• Part Orientation
• Overhangs
• Supports
• Powder removal
• Residual thermal
stresses Distortions

8. Trusted Partner for your Digital Journey
New design
• Manufacturing position and angles
• Holes for powder removal
• Struts to improve honeycomb connection
• Overthickness  milling operation needed
mass reduction: 62%

9. Trusted Partner for your Digital Journey
Lattice Structure…
To reduce distortions and avoid post
machined operations
• Powder Removal
• Minimum Mass
• Structural validation
Cell dimensions
Diameter of bars

10. Trusted Partner for your Digital Journey
Lattice Radius in knot
• Using the minimum radius to save mass
• Admissible stress levels at Knot

11. Trusted Partner for your Digital Journey
New design with Lattice
Lattice integration in the design,
meeting manufacturing criteria
65% of mass reduction

12. Trusted Partner for your Digital Journey
Mechanical analysis validation

13. Trusted Partner for your Digital Journey
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

14. Trusted Partner for your Digital Journey
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?

15. Trusted Partner for your Digital Journey
Thank you