# Part

#### Part

The Part dialogue box has options to select the part to be optimized and define few optimization parameters such as mass fraction, minimum variable fraction for element deletion, element neighbor radius and geometry definitions.

LS-TaSC does not have a limit in terms of number of parts to be optimized. Hence multiple parts can be defined and each part should be assigned optimization parameters separately.

*Mass fraction* is the amount of mass to be retained after optimization process. A mass fraction of 0.25 indicates for example that LS-TaSC will try to retain 25% mass of the part.

A *minimum variable fraction* can be specified by the user, elements with design variable values below this limit will be deleted, which is 0.05 for non-linear problems and 0.001 for linear problems by default.

The design variables of all the elements are updated based on field variable (internal energy density) values of the neighboring elements. A virtual sphere with a radius is defined and elements within this radius are considered to be the neighboring elements (refer to LS-TaSC User’s manual for more information). The default *Neighbor Radius* value is -1.0, which means the results from all elements sharing a node with an element are likely to be used.

Geometry and manufacturing definitions such as symmetry, casting, extrusion and forging can be defined for the part being optimized. Within casting, both one way and two way casting can be defined. There are limitations in terms of number of geometry definitions. A maximum of three geometry definitions can be assigned to each part with maximum of two casting definitions.