The Settings Window for Material
The Settings window for Material () summarizes the predefined or user-defined material properties for a material. This is where you can add or change material properties to fit your model and assign the material to all types of geometric entities: domains (most common), boundaries, edges (3D models only), or points. Also see Material Link and Switch for Materials.
After adding a material (see The Add Material Window and The Material Browser Window), click the Material node (for example, Material 1 or Copper) in the Model Builder. The Settings window for Material opens.
Figure 9-7: Click the Copper node to open the Settings window for Material for the node.
Geometric Entity Selection
Assign the material to some or all entities on a specific Geometric entity level — Domain, Boundary, Edge (3D only), or Point — on the geometry in the Graphics window (the geometry in the model).
By default, the first material in the Component is active in all domains (or all boundaries or edges if the Component only contains surfaces or edges). By assigning other materials to some or all domains, the first material is overridden and remains active only in domains where no other material, added below it in the Materials branch, is active.
If the Component contains features on different geometric entity levels, such as solid mechanics in domains coupled to beams on edges, and the features use the same material, you need to add two Material nodes with the same material, one defined in the domains, and the other defined on the edges.
Override
This section shows if the material, in some or all parts of the geometry where it is active, is overridden by another material added underneath it in the Materials branch, or if it overrides another material above it.
The Overridden by list shows the names of the materials that override this material. The Selection list in the Geometric Entity section displays (overridden) for the geometric entities in which this material is overridden.
The Overrides list shows the names of the materials that this material overrides.
•
Physics Exclusive and Contributing Node Types
•
Physics and Variables Selection
•
Physics Node Status
Material Properties
You can add material properties to the material if they are not already included. To do so, browse the available material property categories (Basic Properties, Acoustics, and so on), and select a material property or a collection of material properties in one of the property groups or material models that appear under the main level of material property categories. Right-click the material property or property group and select Add to Material, or click the Add to Material button () to add the material property or group of properties to the material.
Review the properties listed in the Material Contents table before adding new material properties.
For example, under Acoustics>Viscous Model select Bulk viscosity (muB) and right-click to Add to Material or click the Add to Material button (). If you add a material model like the Viscous Model with more than one property, all of its material properties are added to the Material Contents table. In this example, a Viscous model node is added to the Model Builder and its associated properties are added to the Material Contents table.
To delete a property group, right-click the property group node (in the Model Builder) and select Delete (). The Basic property group cannot be deleted.
A Note About Adding Basic Material Properties
Material properties can be added to the Basic group or to any User-Defined Property Group from two locations — the Settings windows for Material and Property Group.
•
When material properties are added from the Basic node’s or a user-defined group node’s Settings window for Property Group, they are listed under Output Properties and Model Inputs in that Settings window.
•
When material properties are added from the Settings window for Material, the available material properties are listed under Material Properties and are added to the list under Material Contents with the property group listed. The list under Material Contents also contains material properties added from a subnode with a Settings window for Property Group.
Material Type
The Material type setting decides how materials behave and how material properties are interpreted when the mesh is deformed. Select Solid for materials whose properties change as functions of material strain, material orientation, and other variables evaluated in a material reference configuration (material frame). Select Nonsolid for materials whose properties are defined only as functions of the current local state at each point in the spatial frame and for which no unique material reference configuration can be defined.
Simply put, Solid materials associate material properties with specific pieces of the material, and the properties follow the material as it moves around. In particular, a solid material may be inherently anisotropic, meaning that its axes rotate together with the material. The Nonsolid choice, in contrast, applies typically to liquids and gases whose properties are associated with fixed points in space and insensitive to local rotation of the material. Such materials are inherently isotropic when studied in isolation, but may exhibit anisotropy induced by external fields. In practice, this means that any anisotropic tensor properties in a Non-solid material must be functions of some external vector field.
Material Contents
This section lists all of the material properties that are defined for the material or required by the physics in the model. The table lists the Property, Variable, Value, and Unit for the material property as well as the Property group to which the material property belongs. The Property group corresponds to the subnodes in the Model Builder with the same name. If required, edit the values or expression for the property’s Value.
The left column provides visual cues about the status of each property:
•
A stop sign () indicates that an entry in the Value column is required. It means that the material property is required by a physics feature in the model but is undefined. When you enter a value in the Value column, the material property is added to its property group.
•
A warning sign () indicates that the material property has been added to the material but is still undefined. An entry is only required if the material property is to be used in the model.
•
A green check mark () indicates that the property has a Value and is currently being used in the physics of the model.
•
Properties with no indication in the left column are defined but not currently used by any physics in the model.
You can change the value for any property by editing its value directly in the Value column, or, for a selected property, click the Edit button () to enter a value in the window that opens. If the property can be anisotropic, you can choose to enter the values in one of these forms: Isotropic, Diagonal, Symmetric, or Anisotropic. The Variable column lists the variable names corresponding to the degree of anisotropy. For example, for a symmetric electrical conductivity, it contains {sigma11, sigma12, sigma22, sigma13, sigma23, sigma 33}; sigmaij = sigmaji. For an isotropic electrical conductivity, it contains sigma_iso; sigmaii = sigma_iso, sigmaij = 0, where sigma_iso is the name of the variable for the isotropic electrical conductivity (available as, for example, mat1.def.sigma_iso).
Appearance
The settings in this section make it possible to control or change the default appearance of a material in the Graphics window when working in the materials or physics parts of the model tree.
In 3D components, the material is rendered including color and texture when Scene Light is active. In 2D models and in 3D components, when Scene Light is turned off, only a change of color is visible.
The Family list provides quick settings approximating the appearance of a number of common materials — Air, Aluminum, Brick, Concrete, Copper, Gold, Iron, Lead, Magnesium, Plastic, Steel, Titanium, and Water. Select Custom to make further adjustments of the specific settings for colors, texture, reflectance, and so on. The default custom settings are inherited from the material selected last from the Family list.
Specular Color, Diffuse Color, and Ambient Color
For each of these properties, click the Color button to assign a Custom specular color or select a standard color from the list: Black, Blue, Cyan, Gray, Green, Magenta, Red, White, or Yellow.
The combination of Specular color, Diffuse color, and Ambient color gives a 3D object its overall color:
•
Specular color is the color of the light of a specular reflection (specular reflection is the type of reflection that is characteristic of light reflected from a shiny surface).
•
Diffuse color represents the true color of an object; it is perceived as the color of the object itself rather than a reflection of the light. The diffuse color gets darker as the surface points away from the light (shading). As with Ambient color, if there is a texture, this is multiplied by the colors in the texture, otherwise it is as if it has a white texture.
•
Ambient color is the color of all the light that surrounds an object; it is the color seen when an object is in low light. This color is what the object reflects when illuminated by ambient light rather than direct light. Ambient color creates the effect of having light hit the object equally from all directions. As with Diffuse color, if there is a texture, this is multiplied by the colors in the texture; otherwise, it is as if it has a white texture.
For examples of specular, diffuse, and ambient light, which are related to these definitions, see About the 3D View Light Sources and Attributes.
Noise
The Noise check box is selected by default, with the default Normal vector noise scale and Normal vector noise frequency taken from the material. Enter other values as needed, or click to clear the Noise check box.
•
Noise is a texture that disturbs the normals when calculating lighting on the surface. This causes the surface to look rough and textured.
•
Normal vector noise scale is the power of the noise texture. A high value creates a stronger texture of the surface. A value between 0–1 is suitable.
•
Normal vector noise frequency is the size of the noise disturbances. A small value creates smaller features on the texture. A value between 0–10 is suitable.
Diffuse and Ambient Color Opacity
The default Diffuse and ambient color opacity is 1.
Lighting Model
The default Lighting model — Blinn-Phong or Cook-Torrance — is based on the material. Select Simple instead as needed.
The different lighting models provide a set of techniques used to calculate the reflection of light from surfaces to create the appropriate shading. For example, a specular highlight is the bright spot of light that appears on shiny objects when illuminated. Specular highlights are important in 3D computer graphics because they provide a strong visual cue for the shape of an object and its location with respect to light sources in the scene.
For Blinn-Phong, the default Specular exponent is 64. The specular exponent determines the size of the specular highlight. Typical values for this property range from 1 to 500, with normal objects having values in the range 5 to 20. This model is particularly useful for representing shiny materials.
For Cook-Torrance, the default Reflectance at normal incidence and Surface roughness are taken from the material. The Cook-Torrance lighting model accounts for wavelength and color shifting and is a general model for rough surfaces. It is targeted at metals and plastics, although it can also represent many other materials.
•
Reflectance at normal incidence is the amount of incoming light (0–1) from the normal direction (of the surface) that is reflected.
•
Surface roughness is a value that describes microreflectance on the surface. Higher values create a rougher look of the surface with fewer highlights. A value from 0–1 is suitable.