This project is one of the seven projects of the 973 program 'Basic scientific problems of huge heavy-weight manipulators'. There are generally considerable couplings between the surface behaviors of the pairs (friction and clearance) and deformation of the members, the rigid movement and elastic the deformation of the huge heavy-weight manipulators. The redundant motivations and indeterminate structures may cause some uncertain and singular mechanical behaviors. Furthermore, the surface behaviors of the main shafts are extremely complicated. All these factors may affect the performance, accuracy of the manipulator, cause the damage and fatigue of the members, reduce the reliability and fatigue life. This project mainly focuses the studies on (1) nonlinear mechanical behaviors of flexible multibody system; (2) rule of force transformation and topology optimization for members of the huge heavy-weight manipulator; (3) transformation of lubrication state under the unsteady force field; (4) rules of friction and wear on the surface and surface structure optimization of f huge heavy-weight manipulator.