What is the primary purpose of using expressions in design modeling?

The primary purpose of using expressions in design modeling is to automate calculations for design parameters. Expressions allow designers to define relationships between different parameters, making it easier to perform calculations consistently across the design. This capability enables designers to create parametric models that can adapt to changes efficiently; if a dimension or variable needs to be modified, the expression will automatically update related features accordingly. This not only improves the accuracy of the design but also enhances productivity by reducing the need for manual calculations and adjustments throughout the design process.

The other choices, while relevant to various aspects of design, do not capture the core functionality provided by expressions. Aesthetic features, assembly processes, and material properties are important considerations in design but are not directly connected to the specific role of expressions in automating and managing calculations related to design parameters.