Equivalent Bar Conceptions for Computer Analysis of Pantographic Foldable Structures

An equivalent bar conception is firstly developed for the computer analysis of pantographic foldable structures. The uniplet of two three-node beam elements is assumed as a six-bar assembly with respect to least norm least square solution for the elastic strain energy equality. The equilibrium equation is developed for the equivalent models, and the internal forces formulated sequently for backup calculation. This procedure is proved practical for some engineering, and some interesting concepts proposed. Finally, three numerical tests are presented.     

Improvement of the second order approximation of the smoothed particle hydrodynamics

The smoothed particle hydrodynamics (SPH), as a fully Lagrangian particle method, has been successfully applied to astrophysical problems and extended to elastic dynamics and computational fluid dynamics.High order derivatives have to be approximated when elastic dynamics problems are modeled. However, the approximation errors in SPH could lead to computational failure in the case that the order of derivative is high.A novel method was proposed in order to improve the accuracy of SPH method, which shows the relationship between the selected functions and their SPH approximations. The entire involved system was represented by a finite number of particles that carry individual mass and occupy individual space, and the integral interpolation was approximated by a summation interpolation. In addition, error comparison was made between SPH method with and without the present improvement.     

Quasi-static Deployment Simulation for Deployable Space Truss Structures

IntroductionDeployable space trusses have been used wide-ly in the past space missions,and attract increas-ingly the interests of researchers. The essentialcharacteristic is that the geometric configurationtransformation must meetthe limits of the payloadmodule during launch phase and primary require-ments of space mission in orbit.This poses a greatchallenge to numerical simulation.　　 In this paper,Cartesian coordinates of the ide-alized truss nodes are assumed as variables,a newmethod is …     

GEOMETRICALLY NONLINEAR FE FORMULATIONS FOR THE MACRO-ELEMENT UNIPLET OF FOLDABLE STRUCTURES

Introduction　　 Pantographic foldable structure works on theprinciple of a pantograph[1,2 ] . A structure of thistype may be referred to as“pantograph structure”,or simply“p- structure”. The basic unit for the p-structure is a componentso- called duplet[3 ] ,orpan-tograph unit[4] ,Scissor- Like Element ( SLE) [5] ,asshown in Fig.1 .A pantograph unitconsists of twocoplanar straightbars called uniplet,which are ca-pable of rotating about the intermediate pivot,re-ferred to as a scissor h…     

NEW WIND-INDUCED RESPONSES ANALYSIS METHOD OF SPATIAL STRUCTURES IN FREQUENCY DOMAIN WITH MODE COMPENSATION

IntroductionIn response to the demand for architecture anduse function,the span of stadiums or gymnasiumsis enlarging,which inevitably tends to involvelight- weigh roofs,such as membrane.Thesestructures with long natural periods is sensitive towind vibrations,therefore the effects of windloads,especially of dynamic wind loads,are be-coming significant at their design stage.It isknown that these types of structures are apt tohave many natural frequencies in a narrow frequen-cy range.This fact d…     

A method to improve first order approximation of smoothed particle hydrodynamics

Smoothed particle hydrodynamics (SPH) is a useful meshless method. The first and second orders are the most popular derivatives of the field function in the mechanical governing equations. New methods were proposed to improve accuracy of SPH approximation by the lemma proved. The lemma describes the relationship of functions and their SPH approximation. Finally, the error comparison of SPH method with or without our improvement was carried out. Foundation item: The National Natural Science Foundation of China (No. 50778111); The Key Project of Fund of Science and Technology Development of Shanghai (No. 07JC14023)