Lay-up Definition

@LAYUP_DEFINITION {
@LAYUP_NAME {LayUpName} {
@MATERIAL_PROPERTY_NAME {MatPropName}
@LAYER_THICKNESS {t}
@LAYER_DEFINITION {
@MATERIAL_PROPERTY_NAME {MatPropNamei}
@LAYER_THICKNESS {ti}
@ORIENTATION_ANGLES {βi, γi}
}
@LAYER_DEFINITION {
...
}
@COMMENTS {CommentText}
}
}

Introduction

Figure 1. Configuration of a lay-up.

Figure 1 shows the configuration of a lay-up. It consists of N layers of possibly anisotropic material stacked on top of each other. The first layer, layer 1, is at the bottom of the stacking sequence and the last layer, layer N, is at the top. The properties of each layer are to be defined.

The physical characteristics of Layer i are as follows.

  1. A thickness, ti,
  2. material properties, MatPropNamei, and
  3. orientation angles, βi, γi.

Lay-ups are used to define the structural properties of beams, plates, and shells.

  1. SectionBuilder uses lay-ups to define the cross-sectional characteristics beams made of possibly heterogeneous anisotropic material, see solid property definitions.
  2. NormalBuilder uses lay-ups to define the characteristics of plates and shells made of possibly heterogeneous anisotropic material.

Notes

  • It is not uncommon for lay-ups to be made of a single material but the various layers have different orientation angle. In such case, it is convenient to define an optional default material properties, MatPropName, and an optional default layer thickness, t.
  • Each layer of the lay-up is defined in its own subsection starting with the keyword @LAYER_DEFINITION. The first subsection defines Layer 1, the last Layer N. The order in which the subsections appear defines the stacking sequence of the lay-up. The following conventions apply.
    • If the thickness, ti, of a layer is omitted, the default value, t, is used.
    • If the material properties, MatPropNamei, of a layer are omitted, the default value, material properties, MatPropName are used.
    • The orientation angles, βi and γi, must be defined as no default values are provided.
  • Because materials can present anisotropic stiffness and strength properties, the orientation of each layer must be specified accurately. Material properties are defined with respect to a material basis. Orientation angles βi and γi determine the orientation of this material basis with respect to the global reference basis.
    1. If the lay-up is used to define the sectional properties of beams via solid element properties, the procedure to determine the relative orientation of the material basis with respect to the global basis is presented here.
    2. If the lay-up is used to define the properties of plates and shells, the procedure to determine the relative orientation of the material basis with respect to the global basis is presented below.
  • It is possible to attach comments to the definition of the object; these comments have no effect on its definition.

Layer orientation angles

Figure 2. Definition of orientation angle γi
for a laminated composite plate.

Lay-ups are used to define the stacking sequence of composite layers through the thickness of laminated plates and shells. Figure 1 depicts the configuration of a typical laminated plate, consists of N layers of possibly anisotropic material stacked on top of each other.

Figure 2 presents a top view of layer i and shows the interpretation of orientation angle γi as the rotation angle from unit vector b1 of the plate basis to unit vector e1 of the material basis.

Note that the rotation from the plate to the material basis is assumed to be a planar rotation about unit vector b3 = e3. Consequently, the rotation from the plate to the material basis is fully defined by a single orientation angle, γi, and angle βi is not used.

Surveys

Surveys can be defined to evaluate stress and strain distributions through the thickness of lay-ups, within the execution of NormalBuilder. The stress and strain distributions are those associated with the stress resultant defined in the survey. The following SurveyType values and associated FrameName specifications are allowed for lay-ups: NB_STRAINS, NB_STRESSES. (Default value: NB_STRESSES). For lay-ups, no local axis system can be defined.

Examples

Example 1.

The first example creates a four-ply lay-up. Because the material properties and layer thickness are omitted for the first three layers, the default material properties, MatPropT500-4208, and default thickness, t = 0.0625 will be used. The last layer defines its own material properties and thickness.

@LAY_UP_DEFINITION {
@LAY_UP_NAME {LayUp} {
@MATERIAL_PROPERTY_NAME {MatPropT500-4208}
@LAYER_THICKNESS { 0.0625}
@LAYER_DEFINITION {
@ORIENTATION_ANGLES {0.0, 30.0}
}
@LAYER_DEFINITION {
@ORIENTATION_ANGLES {0.0, -30.0}
}
@LAYER_DEFINITION {
@ORIENTATION_ANGLES {0.0, -30.0}
}
@LAYER_DEFINITION {
@MATERIAL_PROPERTY_NAME {MatPropT300-5208}
@LAYER_THICKNESS { 0.0525}
@ORIENTATION_ANGLES {0.0, 30.0}
}
}
}