*heading TRANSVERSE VIBRATION OF "SIMPLY-SUPPORTED" BEAM WITH AND WITHOUT ADDED MASS ******************************************************************* *** RESULTS/ANALYTICAL SOLUTION *** *** Analytical solution: *** f_n = n^2 * (pi/4) * (r/L^2) * sqrt (E/(rho + rho_w)) *** where *** f is the frequency in cycles/time *** n is the number of the mode *** r is the radius of circular cross-section *** L is the length of the structure *** E is the Young's modulus of the material (of the structure) *** rho is the density of material *** rho_w is the density of fluid (or water) *** *** F R E Q U E N C Y T A B L E *** Mode Analytical ABAQUS Analytical ABAQUS *** No Added Mass Added Mass *** 1 0.04011 0.04011 0.03766 0.03766 *** 2 0.16043 0.16041 0.15064 0.15064 *** 3 0.36096 0.3609 0.33894 0.33892 *** 4 0.6417 0.64152 0.60256 0.60249 *** 5 1.0027 1.0022 0.9415 0.94134 ******************************************************************* **************MODEL******** *node 1, 0.0, 0.0 101, 1000.0, 0.0 *ngen, nset=nall 1,101 *element, type=b21 1, 1,2 *elgen, elset=eall 1, 100, 1, 1 *************AQUA********** *aqua -100.0, 100.0, 32.2, 2.0 0., 0., 0., 0. *WIND 1.987E-2, 10., 30.0, 0.0, 1., 0., 0.0 ** rho, Z0, c_x, c_y, dx, dy, alpha *************MATERIAL/SECTION******* *beam section, elset=eall, section=circ , material=mat1 3.0, *material, name=mat1 *elastic 4.32e9, *density 14.91, **************BOUNDARY*********** *boundary 1, 1,2, 0.0 101,2,2, 0.0 **************HISTORY/LOADING******* *restart,write,f=100 ******** *step,perturbation Without added mass *frequency, eigensolver=lanczos, SIM=NO 5, , *OUTPUT,FIELD *MODAL OUTPUT *endstep ******** *step,perturbation With added mass *frequency, eigensolver=lanczos, SIM=NO 5, , *d added mass eall, fi, 6.0, 1.0 *endstep