We　present　a　comprehensive　study　of　nonlinear　resonant　modal　energy　scattering　and　passive　vibration　suppression　in　a　linear　cantilever　beam　with　vibro-impact　nonlinear　energy　sinks　(VI　NESs)　attached　to　it.　It　is　well-known　that　vibro-impacts　are　a　strong　source　of　non-smooth　nonlinearity,　resulting　in　rapid　and　intense　multi-scale　energy　scattering　from　low-to-high　frequencies　in　the　modal　space　of　the　beam.　We　present　a　direct　correlation　between　such　low-to-high　frequency　nonlinear　energy　scattering　induced　by　vibro-impacts　and　vibration　suppression　of　the　beam　vibrations　under　both　sweep-　and　constant-frequency　harmonic　excitations.　In　particular,　we　study　the　intensity　of　the　collisions　between　the　tip　of　the　beam　and　the　particles　of　the　VI　NESs　by　means　of　an　event-driven　method　based　on　an　explicit　variable　time　step　integration　scheme,　and　relate　the　dynamics　of　the　integrated　beam-VI-NES　system　to　the　induced　resonant　energy　scattering　from　low　beam　modes　to　higher　ones.　On　this　basis,　the　effects　of　the　mass　ratio　and　clearance　between　the　absorber　and　the　beam　on　the　resonant　energy　scattering　are　presented.　Our　aim　is　to　perform　predictive　design　of　the　VI　NESs　for　effective　and　robust　vibration　mitigation　of　the　beam　response.　To　this　end　we　perform　optimization　studies　on　the　mass　ratio　and　clearance　between　the　absorber　and　beam　for　the　case　of　single　and　multiple　VI　NESs　and　identify　regions　of　optimal　suppression.　Besides,　since　the　single　VI　NES　is　only　effective　in　a　limited　frequency　and　amplitude　range　–　as　its　dynamics　is　energy-dependent　–　using　multiple　VI　NESs　with　optimized　parameters　can　extend　the　frequency　range　of　effective　vibration　suppression,　rendering　the　resulting　vibration　mitigation　more　robust　to　variations　of　the　applied　excitations.　©　2020　Elsevier　B.V.