2008 International ANSYS Conference

Size: px

Start display at page:

Download "2008 International ANSYS Conference"

Holly Brown
5 years ago
Views:

42 inch railroad wheel radial cross section 2008

4 Example heat treatment cycle Exits 1600 F high furnace (t = 0) 90 seconds dwell time in air 5 minutes water quench on the tread 15 minutes dwell time in air 4 hours temper 6 hours cool down Total time = seconds 2008 ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary

5 Heat treatment description cont d After being heated in the high furnace to the austenitic temperature the tread is water quenched with a spray ring. The as-quenched steel is hard and brittle. To obtain a useful material it is tempered in the low furnace. Tempering slightly lowers the strength but increases the ductility ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary

6 Model / analysis description (1) Decoupled analysis First perform a thermal analysis to get temperature gradients as a function of time minutes. Plane 55 four node thermal elements. Open a new file. Run a structural analysis by mapping the thermal gradients onto the structural elements. 7 hrs. Plane 182 structural element ANSYS, Inc. All rights reserved. 6 ANSYS, Inc. Proprietary

7 Model / analysis description (2) Elastic / Plastic analysis with custom creep. Creep data for our wheel steel was obtained from an independent material testing laboratory. ANSYS personnel wrote the creep equations Standard Steel developed into a custom version of ANSYS. Used bilinear isotropic hardening rule. [@ time = t] Log (creep)=a*t+b*(vm/ys)+c 2008 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary

8 Creep rate vs. temperature for VM/YS families AAR M-107/M-208 Class C 1.0E+00 Creep Rate ("/"/Hr) 1.0E E E E E E E Temperature (F) 1.0*YS 0.9*YS 0.75*YS 0.5*YS 0.30*YS 2008 ANSYS, Inc. All rights reserved. 8 ANSYS, Inc. Proprietary

9 Inelastic deformation types Two types of inelastic deformation. If the inelastic deformation is time dependent it is classed as creep. Strain as a function of time. Plastic deformation is not time dependent ANSYS, Inc. All rights reserved. 9 ANSYS, Inc. Proprietary

More nomenclature: Taping line 2008 ANSYS, Inc.

11 Six material model (1) Brinell readings were measured on a radial cross section of a wheel along the tape line. From the Brinell readings yield strength data was obtained. Yield strength vs. temperature curves were developed from the Brinell readings. Six materials resulted. Yield strength vs. temperature data was input into the macro for 6 materials ANSYS, Inc. All rights reserved. 11 ANSYS, Inc. Proprietary

13 Hoop stress developed during quench E42 hoop stress vs. depth development during 5 min. quench. Custom creep version. hoop stress (ksi) depth = 0.0 depth = 1/4" depth = 1/2" depth = 3/4" depth = 1.0" time (sec) 2008 ANSYS, Inc. All rights reserved. 13 ANSYS, Inc. Proprietary

14 Residual accumulated equivalent strain due creep Accumulated equivalent creep strain due quench and draw vs. depth (in) for five minute quench due quench due draw depth (in) creep strain (ksi) 2008 ANSYS, Inc. All rights reserved. 14 ANSYS, Inc. Proprietary

16 Residual accumulated equivalent plastic strain Accumulated equivalent plastic strain due quench and draw vs. depth (in) for five minute quench due quench due draw depth (in) plastic strain (ksi) 2008 ANSYS, Inc. All rights reserved. 16 ANSYS, Inc. Proprietary

21 Results / Comments Standard Steel is in the process of verifying the calculated stresses using strain gages. The residual stress pattern gives us a good starting point to analyze service conditions ANSYS, Inc. All rights reserved. 21 ANSYS, Inc. Proprietary