{
  "tool": "fixture-stress-comparator",
  "author": "britten-mintz",
  "version": "1.0.0",
  "description": "Structural constants for retail shelving materials. Used in deflection calculations for simply-supported beams under distributed load.",
  "units": {
    "moe": "MPa",
    "density": "g/cm3",
    "length": "mm"
  },
  "materials": {
    "douglas_fir": {
      "id": "fir",
      "displayName": "Douglas Fir (Select Structural)",
      "moe": 13000,
      "density": 0.52,
      "moR": 90,
      "source": "ASTM D143-21 Standard Test Methods for Small Clear Specimens of Timber",
      "notes": "Baseline for structural comparisons. High stiffness-to-weight ratio."
    },
    "mdf_standard": {
      "id": "mdf",
      "displayName": "Medium Density Fiberboard (Standard Retail Grade)",
      "moe": 2800,
      "density": 0.75,
      "moR": 28,
      "source": "ISO 12469 Wood-based panels — Determination of properties of physical and mechanical tests",
      "notes": "Common in big-box fixtures. Low shear strength compared to solid wood."
    },
    "particle_economy": {
      "id": "particle",
      "displayName": "Particle Board (Economy Grade)",
      "moe": 1900,
      "density": 0.68,
      "moR": 22,
      "source": "ANSI/A208.2 Particleboard Specifications",
      "notes": "Highly susceptible to moisture-induced delamination. Not recommended for spans > 600mm without reinforcement."
    }
  },
  "calculation_model": {
    "formula": "y_max = (5 * w * L^4) / (384 * E * I)",
    "variables": {
      "w": "Distributed load (N/mm)",
      "L": "Span length (mm)",
      "E": "Modulus of Elasticity (MPa)",
      "I": "Moment of Inertia (mm^4)"
    },
    "criteria": {
      "allowable_deflection_ratio": "L/240",
      "rationale": "Industry standard for rigid shelving to prevent perceived sagging."
    }
  }
}