Prescribed Accelerations for Sensitivity-Based Optimization Using
Tosca Response Values and Sensitivities
Prescribed acceleration loadings are often caused by gravity fields,
centrifugal loading and rotary acceleration loads. This chapter defines
which kinds of acceleration types for the MSC Nastran®
are feasible for sensitivity-based topology and sizing optimization. These acceleration types are not supported for
shape and bead optimization.
The following commands are supported for acceleration loading:
GRAV: Defines acceleration vectors for gravity or other
acceleration loading.RFORCE: Defines a static loading condition due to
an angular velocity and/or acceleration.ACCEL1: Defines static acceleration loads at individual
GRID points.
The following are not supported:
ACCEL: Defines static acceleration loads, which might vary over a region of the
structural model. The load variation is based on the tabular input defined on
this Bulk Data entry.DMIG,UACCEL: Defines rigid body accelerations in
the basic coordinate system.
Remarks
ACCEL and ACCEL1 might not be available
in all versions of MSC Nastran®.
- Default in Nastran
is to apply lumped mass matrices.
- Applying lumped mass matrices can be enforced using
PARAM,COUPMASS,-1.
- Applying consistent mass matrices can be enforced using
PARAM,COUPMASS,1.
- Tosca Structure
only reads
PARAM,COUPMASS for indicating if lumped mass
matrices or consistent mass matrices are applied. Consequently, if the
METHOD card for RFORCE is applied then
the METHOD card should correspond to the mass element
type chosen in PARAM,COUPMASS.