2008 International ANSYS Conference

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Johnson, John Roth Penn State - Erie 2008

1 2008 International ANSYS Conference Evaluation of Current Density Temperature and Deformations in Sheet Metal Strip and Dome Height Tests Amir Khalilollahi, David Johnson, John Roth Penn State - Erie 2008 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

2 Introduction Applying a direct current to a workpiece during deformation dramatically improves the workability of the metal, without many of the drawbacks of seen with traditional manufacturing processes such as cost, undesired material property changes, etc. Since this previous research only utilized simple uniaxial workpieces, focus is now being turned on to more common and complex 3-D geometries that are seen in industry ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary

3 Objectives To investigate how the current flows through these more complex 3-D geometries and determine if the flow field can be manipulated. To se Finite Element Analysis (FEA) to generate a model that can be used to simulate the effects of current flowing through the work piece by determining the temperature and current density profiles ANSYS, Inc. All rights reserved. 3 ANSYS, Inc. Proprietary

4 Goals To compare to experimental results to show a relationship between the temperature profile and the current density distribution. To vary the parameters of the model to determine if the current density distribution can be modeled. To initiate multi-field FE models to evaluate thermal/structural deformation and stress values in two sheet metal specimens ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary

6 FE Models FE Models are helpful in determining Effect of the clamps on the current flow and heat transfer Effect of contact resistances between workpiece and electrode Effect of convective heat transfer on the temperature distribution Material properties and the temperature dependence of the material properties Evaluation of stress/deformation 2008 ANSYS, Inc. All rights reserved. 6 ANSYS, Inc. Proprietary

7 Results (Dome Model) Thermoelectric Models Parameters were altered in the model to determine if the change affected the temperature and current density distributions. Setup 1: Overall Effect of Applying Current Setup 2: Effect of Duration of Current Setup 3: Effect of Amount of Current Setup 4: Effect of Clamping Locations Setup 5: Effect of Dome Geometry -Height 2008 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary

8 Temperature and Current Density Location: Corner to Corner 323 C TEMPERATURE Location: Corner to Corner Current: 1635 A Time: 15 sec CURRENT DENSITY Actual Max. Temperature 340 C Predicted Max. Temperature 323 C 2008 ANSYS, Inc. All rights reserved. 8 ANSYS, Inc. Proprietary

9 Temperature and Current Density Location: Corner to Side 323 C TEMPERATURE Location: Corner to Side Current: 1655 A Time: 15 sec CURRENT DENSITY Actual Max. Temperature 344 C Predicted Max. Temperature 334 C 2008 ANSYS, Inc. All rights reserved. 9 ANSYS, Inc. Proprietary

10 Temperature and Current Density Location: Adjacent Sides TEMPERATURE Location: Adjacent sides Current: 1655 A Time: 15 sec Actual Max. Temperature 226 C Predicted Max. Temperature 235 C CURRENT DENSITY 2008 ANSYS, Inc. All rights reserved. 10 ANSYS, Inc. Proprietary

12 Results (Dome Model) Summary Parameters were altered in the model to determine if the change affected the temperature and current density distributions. Model produces accurate temperature distributions that match up well with experimental results Model shows relationship between the temperature profile and the current density distribution. Model shows that as the various parameters are changed, the resulting temperature and current density distributions are also affected. By manipulating certain parameters, the flow field of current can be moved to areas of the workpiece that may be prone to failure. By increasing the current density in these areas, the workability is improved and failure is delayed ANSYS, Inc. All rights reserved. 12 ANSYS, Inc. Proprietary

Load Step 1 Structural Model Solid bodies are meshed with

hemisphere-shaped tool CONTA174 and TARGE170 are used for

25 coefficient of friction was used Load Step 1: clamp

13 Load Step 1 Structural Model Solid bodies are meshed with SOLID185 (sheetmetal plate) SOLID186 for clamp rings and hemisphere-shaped tool CONTA174 and TARGE170 are used for contact 0.25 coefficient of friction was used Load Step 1: clamp rings are tightened (5 mm) to firmly hold the plate 2008 ANSYS, Inc. All rights reserved. 13 ANSYS, Inc. Proprietary

Load Step 3 Load Step 3: Indenter is lowered to original position; residual

2 coefficient of friction for structural analysis, thermal contact conductance, but no electrical

16 FE Strip Model SOLID186 for structural analysis SOLID226 with TEMP and VOLT DOF for the thermal-electric simulation CONTA174 and TARGE170 are used for contact 0.2 coefficient of friction for structural analysis, thermal contact conductance, but no electrical contact conductance The aluminum plate is 0.94 mm thick, 50.8 mm wide, and mm long 2008 ANSYS, Inc. All rights reserved. 16 ANSYS, Inc. Proprietary

17 Loading steps Initially the punch in brought into contact with the aluminum plate, with a load of 3 N Thermal-electric transient analysis is performed for a duration of 0.5 sec with 2000 Amps DC The transient is halted at 0.5 seconds and the static structural analysis is updated with the temperatures developed by resistive heating The punch descends into the aluminum plate at a rate of 25.4 mm/minute for the same time interval of 0.5 seconds The geometry is updated from the static structural analysis deformations and the next (0.5 second) transient simulation is performed This alternating looping continues updating each model every 0.5 seconds for 120 steps, (60 sec) of elapsed time 2008 ANSYS, Inc. All rights reserved. 17 ANSYS, Inc. Proprietary

20 Summary The structural FE modeling presented is work in progress mostly due to the needed updates in experimental setup ANSYS can be used to predict the effects of important parameters in the sheet metal fabrication, and in conjunction with the effect of electrical current on workability and joule heating effects The present work has shown that it is feasible to develop a detailed coupled multi-field non-linear FE model that incorporates a looping script to sequentially solve for electrical/thermal/structural fields This would offer determinations of deformations and stresses that are realistic in sheet metal manufacturing process 2008 ANSYS, Inc. All rights reserved. 20 ANSYS, Inc. Proprietary

Finite Element Evaluation Of Thermal Stresses in a Composite Circuit Board Cooled by Mixed Convection

Finite Element Evaluation Of Thermal Stresses in a Composite Circuit Board Cooled by Mixed Convection Amir Khalilollahi Pennsylvania State University, The Behrend College Abstract Present-day interest