Working with materials

What you’ll learn

• Materials in Allsolve: Where materials live in the project and how they relate to physics and simulations
• Adding materials: Add from the library, create a blank material, or generate piezoelectric properties from measurement data
• Material settings: Configure name, target volumes, orientation, and other general options
• Material properties: Add and edit all available physical properties, including isotropic and anisotropic definitions

Materials define the physical behavior of geometric regions in your simulations. They are created and edited in the Physics section and must cover the full geometry before you can run a simulation.

Adding a material

Open a project and go to the Physics section. In the left sidebar, select + next to Materials to open the add menu.

Three options are available:

From library

Select Add from library to add a predefined global or organization material. The library contains:

• Global materials — predefined materials shared with all users (for example, Aluminium, Copper, or FR4)
• Organization materials — materials your organization has saved to its library

When you add a material from the library, its properties are copied into the project. Local changes in the project do not update the library copy, and changes in the library are not reflected in existing project materials.

See Library — Materials for storing and sharing materials through the library.

New material

Select New material to create a blank material. Set the general settings (see below), then add the physical properties your simulation needs with + Add property.

Generate material properties (beta)

Select Generate material properties (beta) → Piezoelectric material to open the piezoelectric material properties characterization tool. This predicts elastic, piezoelectric, dielectric, and damping properties from impedance measurements of a disc-shaped sample and adds the result as a new material.

See Piezoelectric material properties characterization for the full workflow, input requirements, and limitations.

Material settings

Select a material in the Materials list to open its settings panel. The panel has general settings at the top and a Properties section below.

Material settings — name, abbreviation, description, color, target, and orientation

Setting	Description
Name	Display name of the material
Abbreviation	Short identifier shown in the sidebar (for example, Al)
Description	Optional notes about the material
Enabled	Toggle to activate or deactivate the material. Use the button to control activation with an expression — useful for sweeping over materials in parametric studies
Material color	Hex color used to display the material in the model view
Target	Geometric entities the material is assigned to. Select target by using a region, selecting volumes on the model, or by using Pick with rule. You can also share the target as a region for reuse elsewhere in the project
Orientation	Euler angles that define the material coordinate frame for anisotropic properties. Enable the toggle and set the rotation angles when properties depend on direction

At the bottom of the panel:

• Library source — for materials added from the library, shows the origin (for example, Global / Aluminium)
• Save / Discard — commit or abandon changes. Closing the panel with unsaved changes prompts a confirmation dialog

Example material properties with isotropic values and expression inputs

Target not required while editing

You can save a material without assigning a target region, which makes it easier to try different materials. A warning is shown for materials without a target or when material regions overlap. The full geometry must have materials assigned before running a simulation.

Material properties

In the Properties section, select + Add property to open the property picker. Select one or more properties to add. The menu stays open so you can add multiple properties in one pass.

Property picker showing all available material properties

Remove a property with the trash icon on its row, or by clicking again on the list to deselect it.

Property reference

The table below lists all available material properties. Many properties support Isotropic (scalar) or Anisotropic (matrix) definitions through a type dropdown.

Property	Unit	Definition	Typical physics
Coefficient of thermal expansion	1/K	Scalar or 6-component vector	Heat solid, Solid mechanics (thermal strain)
Density	kg/m³	Scalar	Most physics
Dynamic viscosity	Pa·s	Scalar or 3×3 matrix	Laminar flow
Elasticity matrix	Pa	See Elasticity matrix	Solid mechanics, elastic waves, Acoustic waves
Electric conductivity	S/m	Scalar or 3×3 matrix	Current flow, EM waves
Electric permittivity	F/m	Scalar or 3×3 matrix	Electrostatics, EM waves
Heat capacity	J/(kg·K)	Scalar	Heat solid, heat fluid
Magnetic permeability	H/m	Scalar or 3×3 matrix	Magnetism A, H, φ
Mass damping coefficient	1/s	Scalar	Solid mechanics and elastic waves proportional damping
Piezoelectric coupling matrix	C/m²	6×3 matrix	Piezoelectricity
Prony series	Pa	Series	Viscoelasticity — see MEMS 003 example
Speed of sound	m/s	Scalar	Acoustic waves
Stiffness damping coefficient	s	Scalar	Proportional (Rayleigh) damping
Thermal conductivity	W/(m·K)	Scalar or 3×3 matrix	Heat solid, heat fluid
Viscous damping	—	Bulk and shear viscosity, or wave attenuation	Acoustic and elastic wave dissipation

Elasticity matrix

The Elasticity matrix property supports three input modes, selected from a dropdown at the top of the property:

1. Young’s modulus and Poisson’s ratio — enter Poisson’s ratio and Young’s modulus (Pa). Allsolve computes the elasticity matrix internally.
2. Pressure and shear wave velocities — enter pressure wave velocity and shear wave velocity (m/s). Requires Density to be defined.
3. Full elasticity matrix — enter the complete 6×6 matrix directly.

Prony series

The Prony series property defines viscoelastic behavior through relaxation times and corresponding moduli. Use it together with the Elasticity matrix property and a Viscoelastic material model interaction in elastic waves simulations.

Define Prony relaxation times and moduli as lists. See the MEMS 003 — Viscoelasticity benchmark for a complete example.

Viscous damping

The Viscous damping property models dissipation in acoustic and elastic wave simulations. Two definition modes are available:

• Bulk and shear viscosity — enter viscosity values directly
• Pressure and shear wave attenuation — enter attenuation values; requires the Elasticity matrix to be defined using pressure and shear wave velocities

Expressions and variables

Property values accept numeric constants, scientific notation (for example, 68e9), built-in constants (for example, epsilon0, mu0), and project variables and functions. Use expressions to parametrize material properties for sweeps and overrides.

Material properties can also be referenced in interaction expressions through the par namespace (for example, par.epsilon()). See Variable overrides for parametric sweeps over material properties.

For scripting, see the Allsolve SDK — Material reference.

Sweeping over materials

A parametric sweep can switch between materials assigned to the same volume. This is useful when you want to compare how different materials affect simulation results — for example, running the same transient simulation once with water and once with blood as the medium for medical ultrasound.

The approach uses the Enabled field on each material together with a variable override of type Sweep. Each material gets its own enable variable, and the sweep toggles the variables so that exactly one material is active per step.

Setting up a material sweep

1. Create a variable for each material that controls whether it is enabled. For example, define water_enabled with an initial value of 1 and blood_enabled with an initial value of 0.

2. On each material, select the button next to Enabled and enter the corresponding variable. Set the Enabled expression to water_enabled on the Water material and blood_enabled on the Blood material.

   

   Water material — Enabled field set to water_enabled

   

   Blood material — Enabled field set to blood_enabled

3. In Definitions → Variable overrides, create a new override of type Sweep. Add both enable variables and set their override vectors so that exactly one material is active in each step. For two materials, use [1, 0] and [0, 1].

   

   Sweep override — water_enabled [1, 0] and blood_enabled [0, 1]

4. In the simulation’s Inputs, select the sweep override you created.

   

   Simulation inputs — medium_sweep selected

5. Run the simulation. Each sweep step runs with a different material active. Results from all steps are available in plotting, with series labeled by the enable variables.

   

   Plot showing p_avg_front for the water_enabled and blood_enabled sweep steps

Scaling to more materials

The same pattern extends to any number of materials. For three materials, use three enable variables with override vectors like [1, 0, 0], [0, 1, 0], and [0, 0, 1] to run one step per material.

For the full details on sweep types, multivariate sweeps, and override vector syntax, see Variable overrides.

Tips

• Add only the properties your simulation physics require — not every material needs all 15 properties.
• Use Add from library for common materials and customize properties locally as needed.
• Share material targets as regions when the same volume set is used for materials, boundary conditions, or interactions.
• When using frequency-dependent material properties, set the target frequency in simulation settings for transient analyses.