{
  "schema_version": 1,
  "review_date": "2026-10-04",
  "document_kind": "Published source data for research examples",
  "title": "Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings",
  "authors": "Fred B. Oswald; Erwin V. Zaretsky; Joseph V. Poplawski",
  "year": "2012",
  "source_url": "https://ntrs.nasa.gov/citations/20120008398",
  "review_scope": "NASA/TM-2012-217115, Tables II–V, Appendix D worked examples printed pp.27–28 / PDF pp.31–32; Appendix F fitted life factors",
  "readiness": "Runnable static ball-contact comparison; source model differences retained",
  "remaining_inputs": [
    "Distinguish Appendix D approximation from the separate analysis-code result",
    "Preserve crowned-roller effective-length and stiffness conventions",
    "Reconcile printed arithmetic/unit inconsistencies before exact reproduction",
    "Audit life definition independently of contact agreement"
  ],
  "paper_id": "P015",
  "filename": "nasa2012-source-cases.json",
  "website_anchor": "nasa-clearance",
  "source_location": "NASA/TM-2012-217115, Appendix D, printed pp.27-28 / PDF pp.31-32; Tables II-V",
  "native_input_available": true,
  "source_material": {
    "youngs_modulus_mpa": 205900,
    "poisson_ratio": 0.3,
    "reported_effective_modulus_mpa": 226240
  },
  "worked_cases": [
    {
      "name": "210-size deep-groove ball bearing",
      "ball_count": 10,
      "ball_diameter_mm": 12.7,
      "pitch_diameter_mm": 70,
      "race_groove_radius_to_ball_diameter_ratio": 0.52,
      "diametral_clearance_mm": 0.0145,
      "radial_load_n": 627,
      "reported_approximate_stribeck_number": 5.499,
      "source_comparison": "The report states that this approximate result is 2.5 percent above the separate analysis-code result.",
      "reported_combined_contact_coefficient_n_per_mm_power_1_5": 370400,
      "printed_issue": "Step 6 gives Kn=3.704e5, while Step 9 prints 3.704e6 in its denominator. The listed 0.01620 mm estimate agrees with the former exponent. Keep the original PDF unchanged.",
      "native_input_available": true
    },
    {
      "name": "210-size cylindrical roller bearing",
      "roller_count": 14,
      "roller_diameter_mm": 13,
      "nominal_roller_length_mm": 13,
      "pitch_diameter_mm": 70.65,
      "diametral_clearance_mm": 0.045,
      "radial_load_n": 6940,
      "effective_length_ratio_for_crowned_roller": 0.85,
      "derived_effective_length_mm": 11.05,
      "reported_approximate_stribeck_number": 5.876,
      "source_comparison": "The report states agreement within 0.01 percent of its separate analysis-code result.",
      "printed_issue": "The 0.03521 mm first deflection estimate is paired with a printed inch value that differs by a factor of ten. Preserve SI inputs and reconcile intermediate arithmetic.",
      "native_input_available": false
    }
  ],
  "stribeck_definition": "St = rolling_element_count * maximum_normal_element_load / external_radial_load",
  "comparison_boundary": "Maven 52100 steel law at 100 F: E approximately 209618 MPa and nu 0.2959733. NASA source E 205900 MPa and nu 0.3. Maven elliptic iteration and deformed pitch differ from Hou fixed stiffness/Brewe-Hamrock approximation. All loaded-ball counts agree; small edge-of-zone loads require individual review. NASA continuous approximation is distinct from discrete equilibrium; rollers and life remain unqualified.",
  "native_input_filenames": [
    "nasa2012-ball-clearance-627.bearing"
  ],
  "native_comparison_filename": "radial-clearance-comparison.json"
}