1. Fuselage Barrel DFEM example
1500 fasteners included in DFEM effortless using AFFT app approach

2. The structure: 3 m diameter fuselage barrel build up using 3 skin sections

3. The structure: These skins are joined using 3 longitudinal splices

4. The structure: Barrel section includes 2 intermediate frames
The structure: Barrel section includes 2 intermediate frames. They are also build up with 3 different sections…

5. The structure: … which are joined through the corresponding frame splices

6. The structure: In order to materialize all these connections around 1500 fasteners are needed.

7. The mesh: Each part is meshed independently, regardless the fasteners locations.

8. The mesh: Mesh size fixed depending on the number of elements desired between fastener connections.

9. The mesh: Each part meshed has to be exported in a different NASTRAN
The mesh: Each part meshed has to be exported in a different NASTRAN .bdf, in a one part - one file basis.
Part name
BDF File
Skin 1
Skin1.bdf
Skin 2
Skin2.bdf
Skin 3
Skin3.bdf
Skin Splice 1
Splice1.bdf
Skin Splice 2
Splice2.bdf
Skin Splice 3
Splice3.bdf
Frame 1
Frame1.bdf
Frame 2
Frame2.bdf
Part name
BDF File
Frame 1 - Splice 1
Frame1_splice1.bdf
Frame 1 - Splice 2
Frame1_splice2.bdf
Frame 1 - Splice 3
Frame1_splice3.bdf
Frame 2 - Splice 1
Frame2_splice1.bdf
Frame 2 - Splice 2
Frame2_splice2.bdf
Frame 2 - Splice 3
Frame2_splice3.bdf
Each frame is composed by three different sections. Nevertheless they can be grouped in the same BDF as there is not a direct connection between them.

10. The mesh: Parts with big number of elements have been included to show the efficiency of AFFT app.
Number of grids
Number of elements
Skins (each one)
189329
188400
Skin Splices (each one)
6693
6380
Frames (each one)
61692
59784
Frame Splices (each one)
1144
1032

11. Fastener Locations: Lines representing all the fasteners can be created using any design software or preprocessor

12. Fastener locations: Each fastener is represented by a geometrical line.

13. Fastener locations: Fasteners are grouped in part junctions.
SKIN 3 to Skin Splice 3 Junction
SKIN 2 to Skin Splice 3 Junction

14. Fastener locations: Each junction is exported in a different IGES file.
18 Junctions have been defined for current DFEM.
Junction ID
IGES File J1
J1_FR1_Splices1.iges J2
J2_FR1_Splices2.iges J3
J3_FR1_Splices3.iges J4
J4_FR2_Splices1.iges J5
J5_FR2_Splices2.iges J6
J6_FR2_Splices3.iges J7
J7_Skin1_FR1.iges J8
J8_Skin1_FR2.iges J9
J9_Skin2_FR1.iges
Junction ID
IGES File
J10
J10_Skin2_FR2.iges
J11
J11_Skin3_FR1.iges
J12
J12_Skin3_FR2.iges
J13
J13_Skin_1_splice1.iges
J14
J14_Skin_1_splice2.iges
J15
J15_Skin_2_splice2.iges
J16
J16_Skin_2_splice3.iges
J17
J17_Skin_3_splice3.iges
J18
J18_Skin_3_splice1.iges

15. The AFFT application: It can be found at www. afft
The AFFT application: It can be found at and pressing the app button
Field for fastener lines
Fields for meshed parts

16. The AFFT application: Parts have to be introduced in same order as the staking sequence, since connections are built up following the part order.

17. The AFFT application: Example1: Skin1 – Frame1 Connection (2 parts)

18. The AFFT application: Example1: Skin1 – Frame1. Analysis Finished
Log File Information:
lines.iges: 80
Starting reading .bdf files...
reading part 1 ...
80 connections found in part 1
reading part 2 ...
80 connections found in part 2

19. The AFFT application: Example1: Skin1 – Frame1 Fasteners

20. The AFFT application: Example2: Skin1 – Splice 1 Connection (4 parts as they share a few fasteners with Frames 1 and 2)

21. The AFFT application: Example2: Skin1 – Splice 1 fasteners
The AFFT application: Example2: Skin1 – Splice 1 fasteners. Three Part connection example

22. The AFFT application: Processing time depends on the number of fasteners and size of meshed parts to be connected. Few examples are given.
Skin 1 Frame 1 Junction
N Fasteners 80
Part (N_elems)
Skin 1 (188400)
Part 2
(N_elems)
Frame 1 (59784)
Processing time
230 sec
Frame Splice Junction
N Fasteners 32
Part (N_elems)
Skin 1 (188400)
Part 2
(N_elems)
Frame 1 (59784)
Part 3
Frame1 Splice1 (1032)
Processing time
160 sec
Frame Splice Junction (without Skin)
N Fasteners 32
Part 1
(N_elems)
Frame 1 (59784)
Part 2
Frame1 Splice1 (1032)
Processing time
25 sec