Integrating 4D scanning and material optimization for sports bra design

The demand for high-support sports bras has increased since more women with larger and ptotic breasts engage in physical activity. Inadequate control of multidirectional breast motion can lead to discomfort and soft-tissue strain. This study presents an integrated framework combining four-dimensional (4D) breast scanning, composite fabric engineering, and cup-structure optimization to improve motion control and wearer comfort under running conditions. Ten female participants ran at a speed of 8 km/h while dynamic breast models were captured using a Temporal 3dMD system under bare-breast and bra-wearing conditions. The breast surface was divided into 12 directions at 30° intervals. Direction-specific surface deformation was quantified using Euclidean distance changes relative to the papilla base, and the vibration attenuation rate was calculated to evaluate motion reduction. Key dynamic frames, representing pronounced upper-breast deformation, were used to unfold three-dimensional breast models into two-dimensional full-cup patterns in SolidWorks. Two cup structures, i.e. T-shaped and double-vertical, were combined with two laminated fabrics. Interface pressure was assessed using a Pliance-X system. Under running conditions, the double-vertical cups showed a higher vibration attenuation than the T-shaped cups in most assessed directions, with the clearest differences observed in the upper-breast and upper-lateral regions. The three-layer laminated fabric was associated with higher attenuation values than the two-layer fabric in pairwise comparisons, while pressure and subjective comfort results suggested acceptable pressure levels. Incorporating upper-breast deformation characteristics derived from 4D key-frame data significantly improved full-cup conformity during dynamic motion. The proposed approach offers a transferable methodology for designing high-support sports bras for women with larger and ptotic breasts.