On Elephunk, their third album, Los Angeles alterna-rap group the Black Eyed Peas make another bid to crack the big time. To that end, they break out some marquee names — Justin Timberlake, Papa Roach, Brazilian samba legend Sergio Mendes — as well as add a female member, Fergie, to their crew. Party anthems predominate, from the Southern-fried rapid rap “Hands Up” to the Parliament-inflected “Let’s Get Retarded,” and they all achieve their booty-shaking goals. The snags occur with the group’s efforts at grit and substance (the sappy prayer of the Timberlake collaboration, the formulaic rap rock of “Anxiety”), in which cliched observations, preachy lyrics and MTV-ready posturing float atop meticulously detailed production. Ironically, it’s that less inspired material that may finally earn the group its breakthrough hit.