Bra　design　experiences　a　long　process　of　development　including　some　key　aspects　like　material　selection,　pattern　making　and　grading.　The　design　and　development　processes　are　highly　complex,　which　consist　of　many　pattern　engineering　stages,　specialized　technologies　and　multiple　trial-and　errors.　It　is　anticipated　that　a　3D　bra　design　that　incorporates　information　on　the　interaction　between　bra　and　breast　can　effectively　improve　the　design　process　for　optimal　fit　and　comfort.　In　this　paper,　a　novel　personalized　modeling　system　based　on　finite　element　(FE)　contact　model　is　first　presented　to　simulate　the　breast-shaping　effect　and　the　pressure　distribution　of　the　skin　exerted　by　a　bra.　The　new　knowledge　can　provide　a　basis　for　the　computer-aided-design　of　well-fitting　bras　for　the　target　customers.　The　FE　body　sub-models　include　a　rigid　torso　and　two　soft　breasts　wearing　a　bra　with　or　without　an　underwire.　The　geometry　of　the　body　was　based　on　the　3D-scan　data　and　the　property　of　the　breasts　was　considered　a　hyper-elastic　Mooney-Rivlin　model　for　simulating　the　deformation　of　the　breasts.　The　simulation　of　bra　wearing　was　performed　by　an　FE　contact　model　in　a　user-defined　coordinate　system.　There　were　two　main　steps:　(1)　closing　the　shoulder　straps　and　bra　underband　at　the　center　back　of　the　body,　and　(2)　adjusting　bra　position　using　＂virtual　hands＂.　The　simulation　results　showed　that　although　the　wireless　bra　exerted　less　pressure　on　the　breast,　the　shaping　effects　in　terms　of　lifting,　gathering　and　protruding　were　more　obvious　in　the　underwired　bra.　This　result　is　consistent　with　the　actual　bra-wearing.　The　effect　of　wireless　bra　on　the　breast　deformation　was　three　fifths　of　the　effect　of　underwired　bra　and　this　relationship　could　be　used　to　predict　the　deformation　of　breasts　with　different　materials　of　underwire　at　the　early　stage　of　bra　design.　The　relative　errors　between　simulated　results　in　terms　of　the　breast　deformation　and　pressure　distribution　with　a　fitting　experiment　on　an　underwire　bra　were　less　than　10%.　The　FE　model　developed　in　this　study,　therefore,　can　be　used　as　fundamentals　for　various　sensitivity　analyses　about　different　bra　design　features　for　predicting　the　deformation　of　the　breast　shapes　and　comfort　pressure　with　reasonable　accuracy.　(C)　2019　Elsevier　Ltd.　All　rights　reserved.