Vincent Constantin, CADFEM (Suisse) AG

Transcription

1 Fast Titelmasterformat and reliable Bolt durch Assessment Klicken bearbeiten inside ANSYS Vincent Constantin, CADFEM (Suisse) AG

2 Agenda Introduction VDI 2230 Bolt Assessment inside ANSYS Verification Examples Application Example Conclusion 2

3 Titelmasterformat VDI 2230 Part 1 durch Klicken bearbeiten 3

4 Limitations of VDI 2230 Part 1 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 4

5 Titelmasterformat VDI 2230 Part 2 durch Klicken bearbeiten 5

6 Assessment of bolted connections via FEM VDI 2230 Part 2, Chapter 7 Modeling Using FEM-results Verification of bolts 4 model classes 6

7 Model Class III Modeling Reproduce resilience of bolts and all parts involved Bolt represented as a solid -> d N diameter of the shaft -> d 3 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 -> F m_fe_min, F m_fe_max 2 Calculations Consider loss of preload Multi-Zone Mesh 7

8 Realization: verification of load capacity based on VDI 2230 Part 1 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. 8

9 Titelmasterformat Bolt Assessment inside durch ANSYS Klicken bearbeiten Functionality and Workflow 9

10 Automation 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? 10

11 Automation 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 11

12 Workflow 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 Workbench Mechanical, open the protocol 12

13 Post Pre Functionality: Bolt Assessment inside ANSYS Graphical User Interface Background Calculated Forces Parameters Safety factors 13

14 Titelmasterformat Verification durch Klicken bearbeiten VDI 2230, Example 1 14

15 Example 1: Boundary conditions and load case Fixed Support at the end of the rod Frictionless Support around the piston Pressure: 0 MPa at steps 1 and MPa at step 3 Note: steps 1 and 2 are reserved for the pretension and embedding 15

16 Example 1: Results and comparison with reference solution Values VDI 2230 FEM FMperm Dev. [%] FEM FMmin Dev. [%] F_Kmin [N] F_Z [N] F_SA_max [N] F_Smax [N] S_F S_D S_p M_A [Nm] 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). 16

17 Titelmasterformat Verification durch Klicken bearbeiten VDI 2230, Example 2 17

18 Example 2: Model Flange connection with 12 screws Lateral loading on bolts Lower part: fixed Upper part: torsion moment Nm Relevant safety factors: S_P: Pressure S_G: Sliding 18

19 Example 2: Results: Surface Pressure Values VDI 2230:2014 FEM FMperm Deviation [%] F_Smax [N] ApK [mm^2] SP

20 Example 2: Results: Safety factor against sliding VDI 2230:2014 FEM FMmin / bolt min FEM FMmin / bolt max Deviation min [%] Deviation max [%] SG

21 Titelmasterformat Bolted assembly durch Klicken bearbeiten Application of Bolt Assessment inside ANSYS 21

22 Problem Description 25 Bolts M Preload: max N min N 2 Analysis in 3 load steps: preload embedding external loads Questions: M strong enough? Safety factors? Working stress (S_F) Alternating stress (S_D) Surface pressure (S_P) 22

23 Using Bolt Assessment inside ANSYS Results 23

24 Comparison with a classic evaluation Safety factor against exceeding the yield point S_F Time needed by the user [min] Safety factor against surface pressure S_P Safety factor against fatigue failure S_D Bolt 25 Bolts Standard FEA calculation Bolt Assessment inside ANSYS 24

25 Conclusion Standards & regulations Time needed by the user [min] Reproducible methodology 250 Streamlined, automated workflow 200 No more in-house solutions Bolt 25 Bolts Standard FEA calculation Bolt Assessment inside ANSYS 25

26 Wanted: examples and case studies 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: Markus Dutly Vincent Constantin Bolt Assessment inside ANSYS auf YouTube 26

27 Titelmasterformat Simulation makes durch a lot of Klicken things bearbeiten possible Together we can make the most of it. 27