Material Database

The material database turns a standard grade name into a consistent elastic material, so you do not have to type E, G, ν and ρ by hand and get them to agree.

🔧 Grasshopper component

Material Library ElasticAlpaca4d ▸ 00_Material

Inputs

NameMaterial NameText(empty)Type a grade name directly, e.g. S235.

Overrides the dropdowns and moves them to match. An unknown name is an error, not a fallback.

DBPathDatabasePathGeneric(empty)Path to a custom JSON database with the same schema as the built-in ones.

Its type is merged into the Type dropdown, and takes priority over a built-in type of the same name.

ColourColour(empty)The colour the material is drawn in when Model View colours the elements by material — every grade of the list, with Grade set to All.

Left empty, Model View gives each material a colour of its own. Display only: the analysis never reads it.

Outputs

MaterialMaterialA Uniaxial material when Model = Uniaxial, an nD ElasticIsotropic material when Model = nD.

With Grade set to All, a list of them, one per grade.

Options

Three dropdowns live on the component body, under the Library menu:

Dropdown	Values	Default
Type	Steel, Concrete, Timber, Plastic — plus any type found in a custom database	Steel
Grade	All, then the grades of the selected type	S235
Model	Uniaxial or nD	Uniaxial

Set Grade to All for every grade of the type as a list, in the order the database lists them — weakest first for steel, S235 to S450. Pick from it with List Item and a slider to let an optimisation choose the grade. Connect a Panel to the output to read the list: each material shows as its name.

Built-in grades:

Type	Grades
Steel	S235, S275, S355, S450
Concrete	C25_30, C28_35, C30_37, C32_40, C35_45, C40_50
Timber	C14, C16, C18, C20, C22, C24, GOB_Green_Oak
Plastic	PVC, HDPE, PE, PP, PS, PET, PC, PLA, PVA, PTFE, PEEK, PVDF

💡 How the properties are derived

Each database entry stores E and G in MPa and rho in kg/m³. The component:

1. Converts E and G to kN/m² by ×1000.
2. Derives Poisson's ratio from the pair, ν = E/(2G) − 1, clamped to [0, 0.4999].
3. Recomputes G = E / (2(1+ν)) so the triple is internally consistent.
4. Passes rho through unchanged.

The grade name becomes the material name.

💡 Design grade

For a steel grade the material also carries its design grade — fy and fu from EN 1993-1-1 Table 3.1, including the lower values for plates thicker than 40 mm — which Utilisation checks the beam against. The solver never sees it. Only the Uniaxial model carries one, since that is what beams are made of.

💡 Custom databases

A custom database is a JSON object keyed by grade name. The built-in steel file looks like this:

{
  "S235": {
    "rho": 7850,
    "E": 210000,
    "G": 80769,
    "fy": 235,
    "fu": 360,
    "fy_40_80": 215,
    "fu_40_80": 360,
    "epsilon_yield": 0.015,
    "epsilon_max_Stress": 0.11,
    "strainAtRupture": 0.17,
    "material_type": "Steel"
  }
}

E, G, rho and material_type make the elastic material. material_type is what the Type dropdown lists, so give every entry in one file the same value.

An entry whose material_type is Steel and which gives fy is also a design grade, for Utilisation: fy and fu in N/mm² for plates up to 40 mm thick, and fy_40_80 and fu_40_80, if given, for 40 to 80 mm. Strain values are not read.

📈 When to use it

Use it when

• You want a standard grade and want E, G and ν to agree with each other.
• Your office has its own grades or a national standard not in the default set → point DatabasePath at a JSON file.

Do not use it when

• The material is non-standard → use Uniaxial or nD directly.
• You need non-linearity → the database is elastic only. See Moment Curvature for Concrete01, Steel01 and ReinforcingSteel.