Engineering Studies on Structural Integrity of Railroad Tank Cars Under Accident Loading Conditions US Department of Transportation Federal Railroad Administration Office of Research and Development Washington, DC 20590 DOT/FRA/ORD-09/18 Final Report October 2009 NOTICE This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its content or use thereof. NOTICE The United States Government does not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of this report. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED October 2009 Final Report – August 2008 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Engineering Studies on Structural Integrity of Railroad Tank Cars Under Accident Loading Conditions EB034/RR-28 6. AUTHOR(S) D.Y. Jeong, Y.H. Tang, H. Yu, M.L. Lyons, J.E. Gordon, O. Orringer, and A.B. Perlman 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION U.S. Department of Transportation REPORT NUMBER Volpe National Transportation Systems Center Research and Innovative Technology Administration Cambridge, MA 02142-1093 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING Federal Railroad Administration AGENCY REPORT NUMBER Office of Research and Development 1200 New Jersey Ave., SE DOT/FRA/ORD-09/18 Washington, D.C. 20590 11. SUPPLEMENTARY NOTES 12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE This document is available on the FRA Web site at http://www.fra.dot.gov/. 13. ABSTRACT (Maximum 200 words) This report describes research conducted to support the Federal Railroad Administration (FRA) in addressing safety recommendations made by the National Transportation Safety Board (NTSB) regarding a train derailment that occurred near Minot, North Dakota on January 18, 2002. Engineering studies entailing analysis and testing are described, which include (1) analysis of derailment dynamics based on lumped-parameter models, (2) analysis of the structural behavior of tank car components (such as the head and shell) based on finite element modeling, (3) tank car steels characterization based on laboratory testing of samples obtained from tank cars. Specific details of the research are described. Conclusions based on the research findings to date are outlined. The research began to provide FRA with technical support in responding to recommendations made by the NTSB following the Board’s investigation of the Minot accident. Research results are now being applied to support: (1) rulemaking proposed by FRA and the Pipeline and Hazardous Materials Safety Administration to ensure the safe transport of hazardous materials by tank cars and (2) an industry research-and-development effort, called the Next Generation Rail Tank Car Project that was formed to develop and implement new improved designs for tank cars carrying hazardous materials. 14. SUBJECT TERMS 15. NUMBER OF PAGES Accidents, closing speed, finite element analysis, derailment dynamics, hazardous materials, impact 90 loads 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF OF REPORT OF THIS PAGE OF ABSTRACT ABSTRACT Unclassified Unclassified Unclassified NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. 239-18 Preface The Federal Railroad Administration (FRA), Office of Research and Development, sponsored the work described in this report. Specifically, this work was conducted and managed by the Structures and Dynamics Division of the Volpe National Transportation Systems Center (Volpe Center) through a Project Plan Agreement with FRA. Moreover, this work is carried out through the Volpe Center’s Tank Car Structural Integrity Project in FRA’s Rail Equipment Safety Research Program. Ms. Claire Orth (retired) was the Chief of the Equipment and Operating Practices Division. Mr. Francisco González, III is the Project Manager for research on railroad tank cars. Mr. Eloy Martinez also provided technical direction to this project. Part of the work described in this report, specifically the full-scale tank car shell impact tests, was also conducted in support of an industry research-and-development effort called the Next Generation Rail Tank Car (NGRTC) Project. Dow Chemical Company, Union Pacific Railroad, and Union Tank Car Company are the industry sponsors of this collaboration. In January 2007, FRA signed a Memorandum of Cooperation with the industry sponsors of the NGRTC Project to share research information. Transport Canada and the Department of Homeland Security also participated in this project through Memoranda of Cooperation. Professor Christopher Barkan of the University of Illinois at Urbana-Champaign is acknowledged for his assistance in providing access to computers at the National Center for Supercomputing Applications. ii i METRIC/ENGLISH CONVERSION FACTORS ENGLISH TO METRIC METRIC TO ENGLISH LENGTH (APPROXIMATE) LENGTH (APPROXIMATE) 1 inch (in) = 2.5 centimeters (cm) 1 millimeter (mm) = 0.04 inch (in) 1 foot (ft) = 30 centimeters (cm) 1 centimeter (cm) = 0.4 inch (in) 1 yard (yd) = 0.9 meter (m) 1 meter (m) = 3.3 feet (ft) 1 mile (mi) = 1.6 kilometers (km) 1 meter (m) = 1.1 yards (yd) 1 kilometer (km) = 0.6 mile (mi) AREA (APPROXIMATE) AREA (APPROXIMATE) 1 square inch (sq in, in2) = 6.5 square centimeters (cm2) 1 square centimeter (cm2) = 0.16 square inch (sq in, in2) 1 square foot (sq ft, ft2) = 0.09 square meter (m2) 1 square meter (m2) = 1.2 square yards (sq yd, yd2) 1 square yard (sq yd, yd2) = 0.8 square meter (m2) 1 square kilometer (km2) = 0.4 square mile (sq mi, mi2) 1 square mile (sq mi, mi2) = 2.6 square kilometers (km2) 10,000 square meters (m2) = 1 hectare (ha) = 2.5 acres 1 acre = 0.4 hectare (he) = 4,000 square meters (m2) MASS - WEIGHT (APPROXIMATE) MASS - WEIGHT (APPROXIMATE) 1 ounce (oz) = 28 grams (gm) 1 gram (gm) = 0.036 ounce (oz) 1 pound (lb) = 0.45 kilogram (kg) 1 kilogram (kg) = 2.2 pounds (lb) 1 short ton = 2,000 pounds = 0.9 tonne (t) 1 tonne (t) = 1,000 kilograms (kg) (lb) = 1.1 short tons VOLUME (APPROXIMATE) VOLUME (APPROXIMATE) 1 teaspoon (tsp) = 5 milliliters (ml) 1 milliliter (ml) = 0.03 fluid ounce (fl oz) 1 tablespoon (tbsp) = 15 milliliters (ml) 1 liter (l) = 2.1 pints (pt) 1 fluid ounce (fl oz) = 30 milliliters (ml) 1 liter (l) = 1.06 quarts (qt) 1 cup (c) = 0.24 liter (l) 1 liter (l) = 0.26 gallon (gal) 1 pint (pt) = 0.47 liter (l) 1 quart (qt) = 0.96 liter (l) 1 gallon (gal) = 3.8 liters (l) 1 cubic foot (cu ft, ft3) = 0.03 cubic meter (m3) 1 cubic meter (m3) = 36 cubic feet (cu ft, ft3) 1 cubic yard (cu yd, yd3) = 0.76 cubic meter (m3) 1 cubic meter (m3) = 1.3 cubic yards (cu yd, yd3) TEMPERATURE (EXACT) TEMPERATURE (EXACT) [(x-32)(5/9)] °F = y °C [(9/5) y + 32] °C = x °F QUICK INCH - CENTIMETER LENGTH CONVERSION 0 1 2 3 4 5 Inches Centimeters 0 1 2 3 4 5 6 7 8 9 10 11 12 13 QUICK FAHRENHEIT - CELSIUS TEMPERATURE CONVERSIO °F - 40° -22° -4° 14° 32° 50° 68° 86° 104° 122° 140° 158° 176° 194° 212° °C -40° -30° -20° -10° 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100° For more exact and or other conversion factors, see NIST Miscellaneous Publication 286, Units of Weights and Measures. Price $2.50 SD Catalog No. C13 10286 Updated 6/17/98 iv Contents 1. INTRODUCTION ...................................................................................................1 2. ANALYSIS OF DERAILMENT DYNAMICS ......................................................5 2.1 Review of Previous Research ......................................................................5 2.2 Purpose-Built and ADAMS Models ............................................................6 2.3 Sensitivity Studies ........................................................................................7 2.4 Closing Speeds and Impact Forces ............................................................13 2.5 Discussion and Summary ...........................................................................20 3. STRUCTURAL FINITE ELEMENT ANALYSIS ...............................................23 3.1 Verification ................................................................................................24 3.1.1 Sensitivity Studies ..........................................................................25 3.1.2 Static Case Studies .........................................................................37 3.1.3 Dynamic Case Studies ...................................................................39 3.2 Validation ...................................................................................................41 3.2.1 Head Impacts .................................................................................42 3.2.2 Shell Impacts ..................................................................................48 3.2.3 Unnotched Charpy Tests ................................................................54 3.3 Discussion and Summary ...........................................................................59 4. TANK CAR STEELS CHARACTERIZATION...................................................65 4.1 Basic Material Characterization .................................................................66 4.2 High-Rate Fracture Toughness ..................................................................70 4.3 Pendulum Impact Testing of Bulk Fracture Behavior ...............................77 4.4 Discussion and Summary ...........................................................................79 5. CONCLUSIONS....................................................................................................81 6. REFERENCES ......................................................................................................83 APPENDICES A NTSB RECOMMENDATIONS FROM THE MINOT ACCIDENT ...................88 B ESTIMATION OF SAMPLE SIZE AND CONFIDENCE LEVEL .....................89 v Figures 1. Number of Accidents per Year with at least One Car Releasing Hazmat from FRA RAIRS Database .........................................................................1 2. TIH Tank Cars Releasing Lading in Accidents by Year, 1965-2005 [1] ...................2 3. Accident-Caused Releases in TIH Tank Cars, 1965-2005 [1] ...................................2 4. Derailment Buckling Patterns ....................................................................................7 5. Relative Effect of Parameters on Number of Derailed Cars using Purpose-Built Model ..................................................................................................9 6. Relative Effect of Parameters on Number of Derailed Cars using ADAMS Model ..........................................................................................................9 7. Relative Effect of Parameters on Maximum Closing Speed using Purpose-Built Model ................................................................................................10 8. Relative Effect of Parameters on Maximum Closing Speed using ADAMS Model ........................................................................................................10 9. Relative Effect of Parameters on Peak Coupler Force Purpose-Built Model ................................................................................................11 10. Relative Effect of Parameters on Peak Coupler Force ADAMS Model ........................................................................................................11 11. Effect of Train Speed on Number of Derailed Cars from Different Models ...........12 12. Effect of Ground Friction on Number of Derailed Cars from Different Models .....13 13. Characteristic Motions as Possible Sources of Impact .............................................13 14. Maximum Closing Speeds Based on Difference in Translational Velocity .............14 15. Maximum Closing Speeds Based on Difference in Angular Velocity .....................15 16. Maximum Coupler Forces for First 40 Cars of 100-Car Train ................................16 17. Closing Speeds for Initial Contact ...........................................................................17 18. Impact Forces for Initial Contact .............................................................................18 19. Gross Motions of Rail Cars and Post-Derailment, Car-to-Car Impacts ...................18 20. Closing Speeds for Secondary Contact ....................................................................19 21. Impact Forces for Secondary Contact ......................................................................20 22. Simulated and Generalized Car-to-Car Impact Scenarios ........................................21 23. Stills from Surveillance Video of an Actual Train Derailment ................................22 24. Schematic of Dynamic Simulations for Sensitivity Studies .....................................27 25. Schematic of Static Analysis for Sensitivity Studies ...............................................27 26. Comparison of Force-Indentation Results ................................................................30 27. Contours of Equivalent Plastic Strain using Solid Elements ...................................31 28. Contours of Equivalent Plastic Strain using Shell Elements ....................................31 29. Comparison between Static and Dynamic Finite Element Analyses .......................32 30. Comparison between Static and Dynamic Finite Element Analyses .......................33 v i Figures (continued) 31. Contours of Equivalent Plastic Strain from Dynamic Analysis using Shell Elements ................................................................................................33 32. Comparison Force-Indentation Curves from Static Analysis using Shell Elements ................................................................................................34 33. Comparison Force-Indentation Curves from Dynamic Analysis using Shell Elements ................................................................................................35 34. Force-Indentation Curves from Static and Dynamic Analysis using Solid and Shell Elements ..........................................................................................35 35. Comparison of Force-Indentation Curves for Center Loaded Ellipsoidal Cap ........38 36. Comparison of Force-Indentation Curves for Cylindrical Shell ..............................38 37. Comparison between Static and Dynamic FEA for Head Indentation .....................40 38. Comparison between Static and Dynamic FEA for Shell Indentation .....................40 39. Dynamic Lumped-Mass Model for Tank Car Impacts ............................................41 40. Impact Force as a Function of Closing Speed for Head Impacts .............................41 41. Rigid-Deformable Finite Element Model of Tank Container ..................................42 42. Comparison between Calculated and Measured Impact Forces ...............................47 43. Comparison between Calculated and Measured Residual Dent Depths ..................47 44. Comparison between Calculated and Measured Residual Dent Widths ..................48 45. Position of Tank Car in Full-Scale Tests .................................................................49 46. Comparison of Force-Time Histories for Test 0 ......................................................50 47. Comparison of Force-Time Histories for Test 1 ......................................................51 48. Comparison of Force-Indentation Curves for Test 1 ...............................................52 49. Comparison of Force-Time Histories for Test 2 ......................................................53 50. Schematic of Failure Initiation Envelope based on Stress Triaxiality .....................55 51. Schematic of Linear Strain Softening ......................................................................56 52. Comparison of BFCM data for Normalized TC-128B with FEA assuming Bao-Wierzbicki Criterion .........................................................................56 53. Comparison of Different Failure Criteria with BFCM Test Data for TC-128B Tank Car Steel ....................................................................................57 54. Comparison of Measured and Calculated Fracture Energies for Different Steels (Blunt Striker) ................................................................................58 55. Percent Variation in Impact Energy with Parameter Changes .................................59 56. Force-Indentation Characteristic for Shell Impact ...................................................60 57. Typical FEA Mesh for Full-Scale Shell Impact Simulations ...................................61 58. Generalized Impact Scenarios Examined by FEA ...................................................62 59. Distribution of Steels in Pre-1989 Pressure Tank Car Fleet ....................................66 60. Cumulative Distribution of Pressure Tank Car Fleet and Tank Cars used for Testing ........................................................................................................67 61. CVN Data for Cars Involved in Three Different Accidents .....................................69 62. Fracture Toughness Master Curve Applied to Shell Data from Retired Cars ..........73 vi i Figures (continued) 63. Fracture Toughness Master Curve Applied to Shell Data from Minot Cars ............74 64. High-Rate Fracture Toughness as a Function of CVN Energy at 0ºF ......................76 65. High-Rate Fracture Toughness as a Function of CVN Energy at –50ºF ..................77 66. Oversized, Nonstandard Pendulum Impactor ...........................................................77 67. BFCM Test Specimen ..............................................................................................78 68. Impact Tups Used in BFCM Tests ...........................................................................78 69. Fracture Energies for TC-128B Measured in BFCM Tests .....................................79 vi ii