In this paper, a simpler formulation for the nonlinear motion analysis of reticulated space truss structures is developed by applying a new concept of computational mechanics, named the vector form intrinsic finite element (VFIFE or V-5) method. The V-5 method models the analyzed domain to be composed by finite particles and the Newton's second law is applied to describe each particle's motion. By tracing the motions of all the mass particles in the space, it can simulate the large geometrical and material nonlinear changes during the motion of structure without using geometrical stiffness matrix and iterations. The analysis procedure is vastly simple, accurate, and versatile. The formulation of VFIFE type space truss element includes a new description of the kinematics that can handle large rotation and large deformation, and includes a set of deformation coordinates for each time increment used to describe the shape functions and internal nodal forces. A convected material frame and an explicit time integration scheme for the solution procedures are also adopted. Numerical examples are presented to demonstrate capabilities and accuracy of the V-5 method on the nonlinear dynamic stability analysis of space truss structures.

Initial, thermal and wear contours of the work roll are three major sources of mill disturbance and play critical roles in crown and shape control of strip. To simplify the complex contour curve of the work roll resulting from superposition of three kinds of contour mentioned above in the online strip shape control model, a comprehensive contour concept of the work roll and its predictive calculation model are put forward in the present work. Predictive calculation of the comprehensive contour of the work roll in the online strip shape control model during hot rolling consists of two important parts, namely wear contour calculation and thermal contour calculation, which have a direct influence on the accuracy of shape control. A statistical wear model and a finite difference thermal contour model of the work roll are described in the present work. The comprehensive contour is the sum of grinding, wear and thermal contours. This comprehensive contour calculation model has been applied successfully in a real online strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurement and theoretical analysis. The hit rates (per cent of shape index satisfying requirement) of crown and head flatness of the strips rolled by using the shape control model, which includes the comprehensive contour calculation model, have increased about 16 and 10% respectively, compared with that of strips rolled using manual operation.