Materials

Elastic
Hyperelastic
Composite

This section provides a practical overview of the material models available in COMFOR. For detailed theoretical background and mathematical formulations, refer to the Theory section.

Available material models#

Common parameters for all materials#

Every material block requires these base parameters regardless of the underlying constitutive law.

Parameter	Type	Required	Default	Description
`type`	String	Yes	-	Material model keyword.
`density`	Float	Yes	-	Mass density (\(\rho\)).
`damping`	Float	No	`0.0`	Mass proportional Rayleigh damping.

Elastic models#

Elastic materials in COMFOR use the Saint-Venant-Kirchhoff law, which is suitable for small strains but allows for large rotations.

Parameters#

Parameter	Type	Required	Default	Description
`young`	Float	Yes	-	Young's modulus (\(E\)).
`poisson`	Float	Yes	-	Poisson's ratio (\(\nu\)).

Examples#

TOML Fembic

[material.Steel_S235]
type = "ELASTIC"
density = 7.8e-9
young = 210000.0
poisson = 0.3

MATERIALS TYPE ELASTIC Steel_S235 RHO = 7.8e-9 YOUNG = 210000.0 POISSON = 0.3

Hyperelastic models#

Hyperelastic models are designed for materials undergoing finite strains (large deformations), such as rubbers or soft membranes.

Parameters (Ogden)#

Parameter	Type	Required	Default	Description
`potential`	String	Yes	-	Must be set to `OGDEN`.
`mu`	Array	Yes	-	List of shear moduli \(\mu_i\).
`alpha`	Array	Yes	-	List of dimensionless exponents \(\alpha_i\).

Note

The mu and alpha arrays must have the same number of elements. Each pair defines one term of the strain energy potential.

Examples#

TOML Fembic

[material.Rubber]
type = "HYPERELASTIC"
potential = "OGDEN"
density = 1.1e-9
mu = [ -0.09, 13.9, -0.20 ]
alpha = [ -13.7, 0.10, 5.06 ]

MATERIALS TYPE HYPERELASTIC Rubber RHO = 1.1e-9 TYPE = OGDEN MU = [-0.09, 13.9, -0.20] ALPHA = [-13.7, 0.10, 5.06]

Composite#

Designed for anisotropic textile materials (e.g., woven composites). Requires orientation parameters for warp/weft directions and stiffness coefficients.

Parameters#

Parameter	Type	Required	Default	Description
`warp_orientation`	Array	Yes	-	Initial warp fiber unit vector \([x, y, z]\).
`weft_orientation`	Array	Yes	-	Initial weft fiber unit vector \([x, y, z]\).
`k_elong_warp`	Array	Yes	-	Coefficients for warp elongation stiffness.
`k_elong_weft`	Array	Yes	-	Coefficients for weft elongation stiffness.
`k_shear`	Array	Yes	-	Coefficients for in-plane shear stiffness.
`k_bend_warp`	Array	No	`[0.0]`	Optional coefficients for warp bending.
`k_bend_weft`	Array	No	`[0.0]`	Optional coefficients for weft bending.
`k_bend_twist`	Array	No	`[0.0]`	Optional coefficients for twisting stiffness.

Examples#

TOML Fembic

[material.CarbonFabric]
type = "HYPERTEXTILE"
density = 1.5e-9
warp_orientation = [1.0, 0.0, 0.0]
weft_orientation = [0.0, 1.0, 0.0]
k_elong_warp = [150.0, 1000.0]
k_elong_weft = [150.0, 1000.0]
k_shear = [2.1, 4.5]
k_bend_warp = [0.05] # Optional bending

MATERIALS TYPE HYPERTEXTILE CarbonFabric RHO = 1.5e-9 WARPORI = [1,0,0] WEFTORI = [0,1,0] KELONGWARP = [150,1000] KELONGWEFT = [150,1000] KSHEAR = [2.1,4.5] KBENDWARP = [0.05]

Choose a material model#

Use Elastic for small strain applications (e.g., tools).
Use Hyperelastic for finite strain for isotropic materials (e.g., rubber, membranes).
Use Textile Composite for anisotropic woven materials.

For advanced use cases, refer to the Theory section.