clifton-ellis-workshop/joint-constants.json

{
  "schema_version": "1.0.0",
  "title": "Wood Mechanical Property Constants for Structural Joints",
  "author": "Clifton Ellis, Roseville Workshop",
  "date_published": "2026-07-17",
  "license": "CC0-1.0",
  "sources": [
    {
      "id": "FPL-GTR-190",
      "citation": "U.S. Forest Products Laboratory. Wood Handbook: Wood as an Engineering Material, 2nd ed., General Technical Report FPL-GTR-190, Madison, WI: U.S. Department of Agriculture, 2010.",
      "wikidata_reference": "Q76005"
    },
    {
      "id": "NIST-MAT-DB",
      "citation": "National Institute of Standards and Technology Materials Data Repository, moisture correction factors v3.2",
      "access_date": "2026-07-17"
    }
  ],
  "units": {
    "stress": "megapascals (MPa)",
    "density": "grams per cubic centimeter (g/cm³)",
    "length": "millimeters (mm)",
    "force": "newtons (N)",
    "mass": "kilograms (kg)"
  },
  "constants": {
    "standard_moisture_content_percent": 12.0,
    "aerospace_safety_factor_critical": 3.5,
    "operational_envelope_fraction": 0.6,
    "gravity_standard_ms2": 9.80665
  },
  "species_database": {
    "quercus-alba": {
      "common_name": "White Oak",
      "scientific_name": "Quercus alba L.",
      "wikidata_taxon": "Q469555",
      "mechanical_properties": {
        "modulus_of_rupture_MPa": 110,
        "elastic_modulus_compression_MPa": 105,
        "shear_strength_parallel_grain_MPa": 9.8,
        "density_g_cm3": 0.79
      },
      "environmental_factors": {
        "moisture_correction_per_percent_above_12": 0.042,
        "temperature_coefficient_per_K": 0.0012
      },
      "notes": "Preferred species for high-load structural applications. Exceptional resistance to rot and insect damage."
    },
    "pinus-strobus": {
      "common_name": "Eastern White Pine",
      "scientific_name": "Pinus strobes L.",
      "wikidata_taxon": "Q135645",
      "mechanical_properties": {
        "modulus_of_rupture_MPa": 65,
        "elastic_modulus_compression_MPa": 62,
        "shear_strength_parallel_grain_MPa": 5.2,
        "density_g_cm3": 0.37
      },
      "environmental_factors": {
        "moisture_correction_per_percent_above_12": 0.038,
        "temperature_coefficient_per_K": 0.0015
      },
      "notes": "Lightweight construction candidate. Lower absolute strength but superior strength-to-weight ratio for non-critical members."
    },
    "acer-saccharum": {
      "common_name": "Sugar Maple",
      "scientific_name": "Acer saccharum Marshall",
      "wikidata_taxon": "Q130817",
      "mechanical_properties": {
        "modulus_of_rupture_MPa": 125,
        "elastic_modulus_compression_MPa": 118,
        "shear_strength_parallel_grain_MPa": 11.4,
        "density_g_cm3": 0.68
      },
      "environmental_factors": {
        "moisture_correction_per_percent_above_12": 0.040,
        "temperature_coefficient_per_K": 0.0011
      },
      "notes": "Highest MOR in dataset. Recommended for primary load-bearing joints where mass penalty is acceptable."
    },
    "juglans-regia": {
      "common_name": "European Walnut",
      "scientific_name": "Juglans regia L.",
      "wikidata_taxon": "Q130522",
      "mechanical_properties": {
        "modulus_of_rupture_MPa": 95,
        "elastic_modulus_compression_MPa": 88,
        "shear_strength_parallel_grain_MPa": 8.6,
        "density_g_cm3": 0.64
      },
      "environmental_factors": {
        "moisture_correction_per_percent_above_12": 0.041,
        "temperature_coefficient_per_K": 0.0013
      },
      "notes": "Balanced properties with exceptional workability. Ideal for complex joint geometries requiring tight tolerances."
    },
    "abies-grandis": {
      "common_name": "Grand Fir",
      "scientific_name": "Abies grandis (Douglas ex D.Don) Lindl.",
      "wikidata_taxon": "Q470217",
      "mechanical_properties": {
        "modulus_of_rupture_MPa": 72,
        "elastic_modulus_compression_MPa": 68,
        "shear_strength_parallel_grain_MPa": 5.8,
        "density_g_cm3": 0.42
      },
      "environmental_factors": {
        "moisture_correction_per_percent_above_12": 0.039,
        "temperature_coefficient_per_K": 0.0014
      },
      "notes": "Pacific Northwest staple. Moderate strength with excellent dimensional stability under fluctuating humidity."
    }
  },
  "validation_tests": [
    {
      "test_id": "VT-001",
      "description": "White oak dome frame joint (worked example from interface)",
      "inputs": {
        "species": "quercus-alba",
        "moisture_content_percent": 12.0,
        "tenon_depth_mm": 30,
        "shoulder_width_mm": 75,
        "grain_angle_degrees": 0,
        "load_type": "shear"
      },
      "expected_outputs": {
        "rated_capacity_kg": 643.0,
        "safety_margin_percent": 60.75,
        "failure_probability_exponential": "1.2e-4"
      },
      "tolerance_percent": 0.5
    }
  ]
}