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2005 NUMISHEET BENCHMARK STUDY
─ General Instructions

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These instructions are common for all three benchmarks. This document includes details of the material data files and how they are organized, how to register benchmark participation and submit results. The instructions may also be previewed online prior to downloading.

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If there is a time delay from when a participant downloads the files for a specific benchmark and the date they decide to officially register for that benchmark, it is important for them to check “Benchmark Latest News” on the Benchmark homepage prior to registering their participation to be sure that no changes have been made to the benchmark specifications. It should not be necessary to check “Benchmark Latest News” after registering for a specific benchmark participation since notification of updates will be automatically sent to each registered participant, but it is safest to double check for new announcements before submitting final results in case there is some network problem that causes these notifications to be lost.

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Deadlines pertinent to the submission of benchmark results are listed on the website under “Important Dates”.

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Data and instructions for specific benchmarks are described in the instruction document for each benchmark that can be downloaded from the web page for the specific benchmark. The download files include an Instruction File in Word format, several Standard Material Files in Excel format, and for the two application benchmarks, one or more IGES and NASTRAN files to describe the blank shape, tooling geometry and other features. In addition, a Report File template in Excel format is provided for reporting the results for the benchmark. Additional material properties are also available for downloading as explained below.
 

Standard Material Files

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A set of standard material properties is provided for each material in an Excel format. Specification of the experimental methods used to measure these material properties is described in Appendix A. Participants are free to interpret and use these results in the manner they choose. While some may choose to use a Holloman or Voce law, others may want to use the actual true stress- true strain data. The latter presents two problems, first there is more than one set of not-quite-identical stress-strain relations provided in the files, and second, these experimental data are valid only up to uniform elongation. Participants may chose to use their own method of resolving these two problems, but one method that seems to be popular is to choose one of the true stress- true strain sets of data that appears to be most representative of the behavior and append points at higher strain using a modified or scaled version of the fitted stress-strain relation.

 

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While many industrial participants tend to use simple models, the Standard Material File also includes for some materials, data and parameters required for more recently developed anisotropic material models that more accurately describe the material behavior biaxial stress conditions. This additional data, when available, is reported in the Advanced Model worksheet of the Standard Material File. In addition to the Standard Material Files that are linked to the download for the individual benchmark, additional data is available for some materials from a download link on the Benchmark Homepage called “Download Auxiliary Material Data”. This data contains extensive property information on some of the metals, including biaxial tests, pole figures, and crystal orientations, for example. The data is not available for all materials and may be updated as additional testing is completed. Registered benchmark participants will be notified of any updates or additions to the materials used in their benchmarks that are placed in the auxiliary download site and these updates will also be listed in “Benchmark Latest News”. Participants may need to refer to this data to use the more sophisticated material models. See the Appendix of this document for more details.

 

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It is also important to note that the DP 600 material used in Benchmark 2 has different thickness and properties from the DP 600 used in Benchmark 1. These differences can be seen comparing the respective Standard Material Files, BM2_DP600.xls and BM3_DP600.xls.

Registration for Benchmark Participation

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In order to participate in the Benchmark Study, the participant must notify the Benchmark Analysis Committee by sending an email to the address obtained in “Request To Submit Results”. This request must contain the following information:

  1. A designated Primary Contact Person including:

    1. Name:

    2. Organization:

    3. Email address:

    4. Fax and phone number:

  2. How many sets of Registration ID's are requested for Benchmark #1:

  3. How many sets of Registration ID's are requested for Benchmark #2:

  4. How many sets of Registration ID's are requested for Benchmark #3:

  5. Any additional people and organizations that are associated with the analysis:

  6. Is this a request for ADDITIONAL Registration ID's of a previously registered participant? (Yes/No):
    (If Yes, enter only the additional requested ID's in items 2-4 above.)

  7. If you are a previously registered participant and do not intend to submit results using some or all of the assigned Registration ID's numbers, enter the benchmark number and the Registration ID numbers
    that will not be used:

 

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Registration may be done at any time up to one week before the Benchmark Submission Due Date. However, early registration is recommended most importantly because it ensures immediate notification of any changes or other notifications pertinent to the specific benchmarks. These notices will be sent only to the Primary Contact Person. In addition, early registration is useful in planning analysis and conference resources. Registration is considered to only imply an intention to participate, not a commitment to participate and/or attend the conference.

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Each participant who registers will be issued by return email a Registration ID number for each benchmark they indicate they intend to submit results. Also, additional numbers will be issued if the participant indicates that they wish to submit more than one set of predictions for the same benchmark, for example using different material models, or different FE codes. The Benchmark Analysis Committee uses the Registration ID’s to manage and classify submitted results. This is the reason for the unique numbers required for each submission.

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Note: Each benchmark involves one or two processing conditions and two, three, or four materials. To clarify, there is no need for multiple Registration ID numbers to do a complete set of analyses for all processing conditions and materials for a given benchmark. The need for additional Registration ID numbers arises only if the participants want to use more than one material model, or other numerical variation of the analysis. It is expected that each submission will use the same procedure and will be complete for all materials and processing conditions specified in the benchmark with all fields completed in the Benchmark Report File template.

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Participants may request additional Registration ID’s for the same benchmark at a later date through another “Request To Submit Results”, but the second time indicating only the additional number of analyses they intend to submit for each benchmark. However, to avoid duplication of notices to the Primary Contact Person or group, the request should identify the same Primary Contact Person and mention that this is a request for additional ID’s. Also, the Primary Contact Person (only) is encouraged to use “Request To Submit Results” to notify the Benchmark Analysis Committee by email that they do not intend to use one or more of the specific benchmark Registration ID numbers that have been issued to them. The email should indicate both the benchmark number and the registration numbers that will not be used.


Report File and Submission of Benchmark Results

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Results are to be reported using the Benchmark Report File template that is included in the download for the specific benchmark:

BM1_Report_TMP.xlsBM2_Report_TMP.xls BM3_Report_TMP.xls
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The participant must copy the requested results from their analyses into the appropriate cells of the Benchmark Report File and rename the file replacing “TMP” with the Registration ID. For example, if the participant registers to provide two analyses for Benchmark #1 using two different material models and is provided Registration ID numbers 007 and 008, then the Benchmark Report File must be copied and renamed as:

BM1_Report_007.xls,  and

BM1_Report_008.xls

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The Primary Contact Person must submit the completed Benchmark Report File by email to the Benchmark Registration Contact on or before the Benchmark Submission Due Date. To avoid the potential of data capacity limits or other problems, each Benchmark Report must be attached in a separate email. Results (as well as other communications above) will only be accepted from the Primary Contact Person.

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If the file size of the Benchmark Report is too large to be sent by email in a non-compressed form due to server restrictions, the participant may zip the file prior to attaching it to the email. If the file is compressed, it is necessary to rename the file by stripping suffixes, “.xls” and “.zip” from the file after zipping. In the above example, the two files may be submitted in zipped form in individual emails with the attached files named as follows, respectively. It is requested that the files not be zipped if it is possible to send the larger files. The lack of the “.xls” suffix is sufficient to indicate that the file is zipped.

BM1_Report_007,  and BM1_Report_008
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When entering the data in the requested cells of the Report File Excel spreadsheet, the participants must follow these additional general guidelines:

  1. Do not rename the worksheets, relocate cells or otherwise alter the structure of the Report File. The Benchmark Analysis Committee will rely on this fixed format for efficient data analysis, graphing, and other processing.

  2. Do not insert additional data in unused cells or add graphs to the Report File. If participants want to create their own graphs of their results or do their own analysis in other cells of the Excel spreadsheet, these additions should be done in a copy of the Report File rather than the file to be submitted to the Benchmark Analysis Committee.

  3. Enter the number of points used for each requested distribution in the indicated column of ROW 10 above each distribution in the spreadsheet. The Benchmark Analysis Committee uses this information to efficiently include all of the participant’s results in the analysis.

  4. Carefully check the list of data required for the specific benchmark in the Benchmark Instructions File to be certain that all data fields are completed in the spreadsheet. Depending on the screen settings/resolution, it is possible that not all of the data entry fields are visible at one time.

  5. Enter one of the following indices in Column B to the right of the material name under Yield Surface on the General Information worksheet. If the yield surface is not listed, enter “0” in Column B and describe the yield surface model in the Remarks Section at the bottom of the worksheet.

 

ID #

Yield Surface/Plastic Potential

0

Other than one of the models listed below

1

Von Mises

2

Hill 1948 Normal Anisotropic ()

3

Hill 1948 Fully Anisotropic

4

Hill 1979

5

Hill 1990

6

Gotoh

7

Hosford

8

Barlat 1989

9

Barlat 1991

10

Barlat 2000

11

Barlat 2004

12

Karafillis & Boyce

13

Vegter

  1. Enter one of the following indices in Column B to the right of the material name under Hardening Law on the General Information worksheet. If the hardening law is not listed, enter “0” in Column B and describe the nature of the hardening law in the Remarks Section at the bottom of the worksheet.

ID #

Hardening Law

0

Other than one of the models listed below

1

Isotropic

2

Pure Kinematic (Ziegler/Prager)

3

Chaboche

  1. Enter one of the following indices in Column B to the right of the material name under Stress-Strain Relation on the General Information worksheet. Specify which data set or method was used to define the stress-strain relation in Column C or the same row. If the stress-strain relation is not listed, enter “0” in Column B and describe the relation in the Remarks Section at the bottom of the worksheet. Also, if raw data is used (Option 4), specify how the stress-strain relation was extended beyond uniform elongation in the Remarks Section

ID #

Stress-Strain Relation (Column B)

0

Other than one of the models listed below

1

Power Law                             

2

Offset Power Law                           

3

Voce Law                               

4

Raw Data

   

ID #

Data Source for Stress-Strain Relation (Column C)

0

Average over all directions of uniaxial tension tests

1

Rolling direction of uniaxial tension test

2

Biaxial bulge test data

 

  1. Enter values in the Report File according to the following Table:

 

Variable

Form

Units

Precision

Space dimensions

N/A

mm

0.1

Stress

True Stress

MPa

0.1

Strain

True Strain

Dimensionless [not as a percent]

0.1

 

 

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Any files not following these instructions will be returned for correction. The Benchmark Analysis Committee will make every effort to include all submissions in their study and report that are received before the Benchmark Submission Due Date. However, since each submission will be treated as a Read-Only file, any modifications required to satisfy the above requirements are expected to be made by the participants in a timely manner to meet the committee’s deadlines.

 

 

Appendix A

 

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The following tests and procedures are followed in preparing the material data of the metals used in the benchmarks and are generally provided by the material supplier who is participating in the benchmark in which their materials are being used.

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Uniaxial tension tests are performed in three orientations (L – along the rolling direction, T – 90 degree to the rolling direction and D – 45 degree to the rolling direction) with three replicates for each orientation (9 sets of data). A single speed of 1 inch/min (25.4 mm/sec) was used during the entire test using a 2-inch (50.8 mm) extensometer for strain and elongation measurements. The following 9 sets of measurements are obtained from these tests:

  1. Engineering stress vs. total engineering strain up to the Total Elongation (TE). Results are reported on one worksheet in the Standard Material File.

  2. True stress vs. true plastic strain up to Uniform Elongation (UE). Results are reported on one worksheet in the Standard Material File.

  3. The 0.2% Offset Yield Surface, the Ultimate Tensile Strength (UTS), the Uniform Elongation (UE), the Total Elongation (TE), and power law fits (K and n) to the true stress vs. true plastic strain are reported on the worksheet entitled “Average”. An average is calculated from these values over all tensile tests and reported in the worksheet entitled “Summary”.

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Manual r-value measurements after unloading (instead of automatic in-situ measurements with extensometer that requires subtraction of the elastic component) are made in all three orientations with three replicates for each orientation (9 sets of data). These tests are to be terminated at 10% strain in the case of aluminum alloys and at the next whole percentage number below uniform elongation for steels (for example, if the uniform elongation is 18.7%, then the r-value will be measured at 18% strain). These results are reported in the Standard Material File in the worksheet entitled “Average” and the normal anisotropy value is reported in the worksheet entitled “Summary”.

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Forming limits curves (FLC’s) are provided in a separate worksheet of the Standard Material File. However, it should be noted that this data is for reference purposes only, since the benchmarks are designed not to exceed the formability limits of the materials. These FLC’s may be either experimental or theoretical in origin.

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Friction measurements are provided by IRDI using the Twist Compression Test. Additional testing using the Drawbead Test and other methods have also been done. A coefficient of friction based on these tests and experience is given in the “Summary” worksheet of the Standard Material File.

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Tests were done on some materials that provide parameters required for the more sophisticated material models. Many of these test results are summarized in the Advanced Model worksheet of the Standard Material File. Additional files for selected materials and measurements can be downloaded from the “Download Auxiliary Material Data”. These additional data include the following:

  1. A general summary of all measurements for the aluminum alloys used in Benchmark 2 and Benchmark 3 including uniaxial, equibiaxial tensile measurements, Barlat model coefficients, and pole figures, included in the Word file BM_Aluminum.doc. Most of this is included in the Standard Material File for these materials.

  1. Stress-strain data for two sets of tensile samples in 15-degree increments in orientation relative to the rolling direction. These are reported in the files BM2_AL5182_15.xls and BM3_AL6011_15.xls.

  1. A list of Euler angles for a representative sample of 1000 grains are provided in two text files, BM2_AL5182_texture.txt and BM3_AL6011_ texture.txt.

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Additional tests are planned and may be added to the “Download Auxiliary Material Data”. If this data is available for all materials, then the format of the Standard Material File may be updated to include the new data. A notice of these changes will be posted under “Benchmark Latest News” and registered benchmark participants will also be notified. The tests currently considered are:

  1. Biaxial tension tests using the Marciniak Cup test with in-site stress measurement by X-ray diffraction.

  1. Additional hydraulic bulge equal-biaxial stretch test.

  1. Uniaxial tension-compression tests

  1. Three-point bend test

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