1!$Id:$ 2 subroutine shap1d( xi, nel, shp ) 3 4! * * F E A P * * A Finite Element Analysis Program 5 6!.... Copyright (c) 1984-2017: Regents of the University of California 7! All rights reserved 8 9!-----[--.----+----.----+----.-----------------------------------------] 10! Purpose: One dimensional shape functions and natural derivatives 11 12! Inputs: 13! xi - Isoparametric coordinate: ( -1 < xi < 1 ) 14! nel - Number of nodes / element : ( 2 or 3 ) 15 16! Outputs: 17! shp(2,3) - Shape functions and spatial derivatives 18! (natural derivatives only) 19! shp(1,i) - Shape function spatial derivative: N_i,xi 20! (natural derivatives only) 21! shp(2,i) - Shape function : N_i 22!-----[--.----+----.----+----.-----------------------------------------] 23 24 implicit none 25 26 integer nel 27 real*8 xi, xi2 28 29 real*8 shp(2,nel) 30 31 save 32 33! 2-node shape functions and derivatives 34 35 if(nel.eq.2) then 36 37 shp(1,1) = -0.5d0 38 shp(1,2) = 0.5d0 39 40 shp(2,1) = 0.5d0 - 0.5d0*xi 41 shp(2,2) = 0.5d0 + 0.5d0*xi 42 43! 3-node shape functions and derivatives 44 45 elseif(nel.eq.3) then 46 47 xi2 = xi*xi 48 49 shp(1,1) = xi - 0.5d0 50 shp(1,2) = xi + 0.5d0 51 shp(1,3) = -xi - xi 52 53 shp(2,1) = 0.5d0*(xi2 - xi) 54 shp(2,2) = 0.5d0*(xi2 + xi) 55 shp(2,3) = 1.0d0 - xi2 56 57 endif 58 59 end 60