{
  "standard": {
    "name": "ISO 898",
    "wikidata": "Q5974435",
    "description": "Mechanical properties of fasteners made of carbon steel and alloy steel",
    "authority": "International Organization for Standardization"
  },
  "grades": {
    "8.8": {
      "tensile_strength_MPa": 800,
      "yield_strength_MPa": 640,
      "yield_ratio": 0.80
    },
    "10.9": {
      "tensile_strength_MPa": 1000,
      "yield_strength_MPa": 900,
      "yield_ratio": 0.90
    },
    "12.9": {
      "tensile_strength_MPa": 1200,
      "yield_strength_MPa": 1080,
      "yield_ratio": 0.90
    }
  },
  "physics": {
    "equation": "T = K × d × F",
    "variables": {
      "T": {
        "symbol": "T",
        "unit": "N·m",
        "description": "Applied torque"
      },
      "K": {
        "symbol": "K",
        "unit": "dimensionless",
        "description": "Nut factor (coefficient of friction)",
        "typical_range": {
          "min": 0.12,
          "max": 0.25,
          "default_dry_steel": 0.20,
          "mos2_coated": 0.12
        }
      },
      "d": {
        "symbol": "d",
        "unit": "mm",
        "description": "Nominal diameter"
      },
      "F": {
        "symbol": "F",
        "unit": "N",
        "description": "Target preload force"
      }
    }
  },
  "material_constants": {
    "yield_strength_entity": "Q3807177",
    "coefficient_of_friction_entity": "Q1932524",
    "torque_to_yield_entity": "Q7826786"
  },
  "operational_limits": {
    "max_preload_percent_yield": 90,
    "standard_preload_percent_yield": 75,
    "torque_tolerance_percent": 10
  },
  "work_example": {
    "application": "Habitat Pressure Seal",
    "fastener": "M12 × 1.75",
    "grade": "10.9",
    "effective_area_mm2": 84.3,
    "yield_force_kN": 75.9,
    "target_clamp_kN": 56.9,
    "nut_factor": 0.20,
    "target_torque_Nm": 1.37,
    "acceptable_range_Nm": {
      "min": 1.23,
      "max": 1.51
    }
  },
  "metadata": {
    "author": "Albert Karaca",
    "location": "Saint Anthony, Idaho",
    "version": "1.0",
    "build_date": "2026-07-17",
    "purpose": "Machine-readable specification for torque compliance calculation"
  }
}