OptiStruct is a proven, modern structural solver with comprehensive, accurate and scalable solutions for linear and nonlinear
analyses across statics and dynamics, vibrations, acoustics, fatigue, heat transfer, and multiphysics disciplines.
Descriptions for individual I/O Option Entries can be accessed by selecting from the links for each entry, listed
below in groups according to their purpose and alphabetically on the I/O Options Section page.
Descriptions for individual Subcase Information Entries can be accessed by selecting from the links for each entry,
listed below in groups according to their purpose and alphabetically on the Subcase Information Section page.
In order to prevent analyses from being carried out on badly discretized models, an element quality check
is incorporated into the pre-processing phase.
The element check and default bounds of the CGASK12 element are identical as those of the second-order (15-noded) CPENTA element. Notice that CGASK12 has six 3-node edges of which Hoe Normal Offset and Hoe Tangent Offset are checked.
The element check and default bounds of the CGASK16 element are identical as those of the second-order (20-noded) CHEXA element. Notice that CGASK16 has 8 3-node edges of which Hoe Normal Offset and Hoe Tangent Offset are checked.
In order to prevent analyses from being carried out on models with poor material definitions, a material property
check is incorporated into the pre-processing phase. The material property check is controlled by the CHECKMAT parameter (see the PARAM input format).
The OptiStruct Example Guide is a collection of solved examples for various solution sequences and optimization types and provides
you with examples of the real-world applications and capabilities of OptiStruct.
In order to prevent analyses from being carried out on badly discretized models, an element quality check
is incorporated into the pre-processing phase.
The following qualities of the CHEXA 1st-order
element are checked:
Aspect Ratio
The aspect ratio of a CHEXA 1st-order element is
defined as the maximum aspect ratio among its six faces; each treated as
a CQUAD4 element.
Face Skew Angle
The face skew angle of a CHEXA 1st-order element is
defined as the maximum skew angle among its six faces; each treated as a
CQUAD4 element.
Vertex Angle
The same vertex angle check is performed for all of the faces, and each
is treated as a quadrilateral (CQUAD4) element. The
minimum and maximum values reported for the element.
Face Warpage
The face warpage of a CHEXA 1st-order element is
defined as the maximum warpage among its six faces; each treated as a
CQUAD4 element.
Twist Angle
The twist angle of a CHEXA 1st-order element is
defined as the maximum rotation of one face with respect to its opposite
face. The calculation is done as:
Then, for each pair of opposing faces, a reference plane that is
perpendicular to the axis connecting the centroids of the faces is
constructed. The diagonal vectors and of each of the two opposite faces are
projected onto this reference plane. The angles between the projected and the projected are computed as and . The maximum of and is defined as the relative rotation
between these two opposite faces (TAF). Finally, the twist angle (TA) of
a CHEXA 1st-order is calculated as the maximum
relative rotation of its three pairs of opposing faces.
Edge Angle
An edge angle is the absolute value of the angle between two faces
sharing a common edge, subtracted from 90 degrees. For warped faces, the
projected planes are used to compute the face normals used for the angle
calculation. The edge angle of a CHEXA 1st-order is
defined as the maximum edge angle in the element.
CHEXA 1st-order Default Bounds
Information
Default values for warning message
Default values for error message
Default values for validity check
Lower Limit
Upper Limit
Lower Limit
Upper Limit
Lower Limit
Upper Limit
Aspect Ratio
-
100.0
-
1000.0
-
1.0E5
Face Skew
Angle
-
60.0
-
75.0
-
90.0
Face Warp
Angle
-
30.0
-
60.0
-
180.0
Twist Angle
-
30.0
-
90.0
-
180.0
Edge Angle
-
60.0
-
85.0
-
90.0
CHEXA 2nd-order (20-noded) Element Checks
The following qualities of the CHEXA 2nd-order
element are checked:
Aspect Ratio
This quality is calculated using only the corner nodes. Its definition
is the same as that used for the CHEXA 1st-order
element.
Face Skew Angle
This quality is calculated using only the corner nodes. Its definition
is the same as that used for the CHEXA 1st-order
element.
Vertex Angle
This quality is calculated using only the corner nodes. Its definition
is the same as that used for the CHEXA 1st-order
element.
Face Warpage
This quality is calculated using only the corner nodes. Its definition
is the same as that used for the CHEXA 1st-order
element.
Twist Angle
This quality is calculated using only the corner nodes. Its definition
is the same as that used for the CHEXA 1st-order
element.
Edge Angle
This quality is calculated using only the corner nodes. Its definition
is the same as that used for the CHEXA 1st-order
element.