Impact of CATIA-Based Parametric Design on Variant Management in Bus Interiors

This paper presents a CATIA-based approach for managing seat layout (2+2 → 2+1) and overhead service-set (Basic → Premium) transitions under a single parametric architecture. The architecture comprises two skeletons (SeatLayout_Skeleton and ServiceSet_Skeleton), a standardized Publications interface, Excel Design Table-driven variants (pitches 750/720/950 mm; rows 10/12/8), Knowledgeware rules (min-max checks, alignment metric AlignmentDeviation_mm, user warnings), and UDF/PowerCopy attachment templates. In the case study, changes in seat pitch and row count automatically synchronize the service-set modules, while DMU validation reports alignment and clash results. Across three representative variants (750/10, 720/12, and 950/8), the proposed workflow reduced engineering update time by 80% compared with the conventional method. DMU analysis detected zero Seat–Seat and Seat–Service clashes, while alignment deviations remained within the predefined engineering targets, with average values of 0.4–0.6 mm and maximum values of 1.2–1.5 mm. The framework is reusable, scalable, and auditable. In addition, the study contributes to Knowledge-Based Engineering (KBE) research by proposing a dual-skeleton interface architecture that improves model stability and variant synchronization in complex CAD assemblies.