Schraubenberechnung "inside"ANSYS nach der Richtlinie VDI 2230 Die Richtlinie VDI 2230 sieht einen Berechnungsablauf vor, der die Montage, die Beanspruchung unter statischen und dynamischen Lasten, die Flächenpressung sowie das Abscheren der Gewindegänge berücksichtigt. Als Nennspannungskonzept sind für den Nachweis keine Auswertungen der Spannungen aus der FEM-Analyse notwendig. Die aus der Analyse ermittelten Kräfte und Momente sind für die Verarbeitung ausreichend. Wer diese für einen richtlinienkonformen Nachweis nutzen mochte, musste bisher selbst manuell aktiv werden: Die erforderlichen Größen aus der FEM-Berechnung mussten extrahiert, übertragen und in weiterer Folge per Tabellenkalkulation oder separater Software verarbeitet werden. Das neue Softwaremodul von CADFEM „Bolt Assessment inside ANSYS“ bietet mit einem in ANSYS Workbench integrierten Nachweis konform der VDI-Richtlinie 2230 die ideale Lösung.

1. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
Fast and reliable Bolt Assessment “inside ANSYS”
Vincent Constantin, CADFEM (Suisse) AG
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien

2. © CADFEM 2015
Agenda
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 2
• Introduction
• VDI 2230
• Bolt Assessment inside ANSYS
• Verification Examples
• Application Example
• Conclusion

3. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
VDI 2230 Part 1
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 3

4. © CADFEM 2015
Limitations of VDI 2230 Part 1
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 4
• Nonlinear material behavior (e.g. plasticity, creeping)
• Nonlinear status (i.e. load dependent contacts, sealings incl. fluid
penetration)
• Geometric nonlinearities (large deflections during upward movement)
• Plates stiffness has to be estimated
• The load introduction factor n has to be estimated
• Finding the length of lever arm a for an eccentric force transmission can be
quite difficult, calculations are cumbersome…
Source: User Manual KISSsoft
Source: User Manual KISSsoft

5. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
VDI 2230 Part 2
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 5

6. © CADFEM 2015
Assessment of bolted connections via FEM
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 6
• VDI 2230 Part 2, Chapter 7
• Modeling
• Using FEM-results
• Verification of bolts
• 4 model classes

7. © CADFEM 2015
Model Class III
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 7
• Modeling
• Reproduce resilience of bolts and all parts
involved
• Bolt represented as a solid
-> dN diameter of the shaft
-> d3 diameter of the thread
Head and screw nut will not be modeled in
detail, thread resilience will not be modeled,
this will result from the local displacement
• Preload is included
-> Fm_FE_min, Fm_FE_max 2 Calculations
• Consider loss of preload
• Multi-Zone Mesh

8. © CADFEM 2015
Realization: verification of load capacity based on VDI 2230 Part 1
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 8
For a verification in dependence upon VDI 2230 the following loads must be
below the acceptable threshold:
• Working stress
• Alternating stress
• Surface pressure at the bolt head and nut bearing area
• Safety factor against sliding
In addition a sufficient length of engagement has to be provided.

9. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
Bolt Assessment inside ANSYS
Functionality and Workflow
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 9

10. © CADFEM 2015
Automation
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 10
• Goals:
• Automation of bolt calculation for the model class III
• Forces and moments in the bolts are automatically measured
• Using external database to simplify the user‘s work
• What is needed?
• New load object: bolt pretension with additional properties
• New result object: post-processing, display of calculated safety factors
• Accessing database and calculation module of KISSsoft
• How to implement it?

11. © CADFEM 2015
Automation
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 11
• How to implement it?
• Application Customization Toolkit (ACT)
• Enhance usage of ANSYS by integrating own
functionality
• Implement load and result objects
• Define special settings in details view
• Access the graphics window

12. © CADFEM 2015
Workflow
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 12
1. Model preparation: Solid Bolts and Mesh
2. Add new Bolt Load to project tree
• Insert parameters
3. Add new Bolt Assessment to post
processing section of project tree
• Select Type of Result
4. Solve
5. Review results in WB, open the Protocol

13. © CADFEM 2015
Functionality: Bolt Assessment inside ANSYS
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 13
Calculated Forces
Parameters
PrePost
Back-
ground
Graphical User Interface
Safety factors

14. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
Verification
VDI 2230, Example 1
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 14

15. © CADFEM 2015
Example 1: Boundary conditions and load case
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 15
• Fixed Support at the end of the rod
• Frictionless Support around the
piston
• Pressure:
• 0 MPa at steps 1 and 2
• 5.5 MPa at step 3
• Note: steps 1 and 2 are reserved for
the pretension and embedding

16. © CADFEM 2015
Example 1: Results and comparison with reference solution
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 16
Values VDI 2230 FEM FMperm Dev. [%] FEM FMmin Dev. [%]
F_Kmin [N] 1000.00 36592.35 - 1203.11 20.31
F_Z [N] 2415.00 2491.61 3.17 2501.33 3.57
F_SA_max [N] 1394.40 1423.60 2.09 1729.57 24.04
F_Smax [N] 66194.00 66223.60 0.04 28650.57 -
S_F 1.15 1.15 -0.28 2.66 -
S_D 5.89 5.79 -1.79 4.76 -19.17
S_p 1.77 1.68 -4.76 3.89 -
M_A [Nm] 108.00 109.15 1.06 - -
• With the values of the KISSsoft’s database, the
calculated contact surface is smaller than in the
reference solution. Thus the safety factor against
surface pressure (S_p) is more conservative.
• With the minimal preload, the additional bolt load is
greater because of a partial separation at the
interface. This leads to a smaller safety factor against
fatigue failure (S_D).

17. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
Verification
VDI 2230, Example 2
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 17

18. © CADFEM 2015
Example 2: Model
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 18
• Flange connection with 12 screws
• Lateral loading on bolts
• Lower part: fixed
• Upper part: torsion moment
• 13 000 Nm
• Relevant safety factors:
• S_P: Pressure
• S_G: Sliding

19. © CADFEM 2015
Example 2: Results: Surface Pressure
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 19
Values VDI 2230:2014 FEM FMperm Deviation [%]
F_Smax [N] 118800.00 118800.00
ApK [mm^2] 151.50 151.20 -0.20
SP 1.08 1.08 -0.22

20. © CADFEM 2015
Example 2: Results: Safety factor against sliding
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 20
VDI 2230:2014 FEM FMmin / bolt min FEM FMmin / bolt max Deviation min [%] Deviation max [%]
SG 1.26 1.26 1.29 0.01 1.96

21. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
Bolted assembly
Application of Bolt Assessment inside ANSYS
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 21

22. © CADFEM 2015
Problem Description
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 22
• 25 Bolts M12 – 8.8
• Preload:
• max 40 000 N
• min 16 000 N
• 2 Analysis in 3 load steps:
• preload
• embedding
• external loads
• Questions:
• M12 – 8.8 strong enough?
• Safety factors?
• Working stress (S_F)
• Alternating stress (S_D)
• Surface pressure (S_P)

23. © CADFEM 2015
Using Bolt Assessment inside ANSYS
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 23
• Results

24. © CADFEM 2015
Comparison with a classic evaluation
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 24
• Safety factor against exceeding
the yield point S_F
• Safety factor against surface
pressure S_P
• Safety factor against fatigue
failure S_D
0
50
100
150
200
250
1 Bolt 25 Bolts
Time needed by the user [min]
Standard FEA calculation Bolt Assessment inside ANSYS

25. © CADFEM 2015
Conclusion
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 25
• Standards & regulations
• Reproducible methodology
• Streamlined, automated workflow
• No more in-house solutions
0
50
100
150
200
250
1 Bolt 25 Bolts
Time needed by the user [min]
Standard FEA calculation Bolt Assessment inside ANSYS

26. © CADFEM 2015
Wanted: examples and case studies
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 26
• Would you like to learn more?
• We are looking for your bolt calculations and cases!
• You provide your model including all hand calcs
• We will verify the bolts using our Bolt Assessment inside ANSYS
• We compare your results with the ones from Bolt Assessment inside ANSYS.
• Conditions: your test case will be published
• Contact us:
• Matthias Alberts (matthias.alberts@cadfem.at)
• Vincent Constantin (vincent.constantin@cadfem.ch)
Bolt Assessment inside ANSYS auf YouTube
https://youtu.be/wQYN5S9PHus

27. Titelmasterformat durch Klicken bearbeiten
© CADFEM 2015
Simulation makes a lot of things possible
Together we can make the most of it.
ANSYS Conference & 10. CADFEM Users' Meeting, 29.-30. April 2015, Wien 27