*heading TRANSVER VIBRATION OF "CLAMPED-FREE" (CANTILEVER) BEAM WITH AND WITHOUT ADDED MASS ******************************************************************* *** RESULTS/ANALYTICAL SOLUTION *** *** Analytical solution: *** f_n = (an/(4 pi)) * (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) *** a_n is a constant for the "n"th mode [only for ANALYTICAL soln] *** *** F R E Q U E N C Y T A B L E *** Mode a_n Analytical ABAQUS Analytical ABAQUS *** No Added Mass Added Mass *** 1 (3.516) 0.01429 0.01429 0.01342 0.01342 *** 2 (22.03) 0.08952 0.08952 0.08406 0.08406 *** 3 (61.7) 0.25071 0.2506 0.2354 0.2354 *** 4 (120.9) 0.4913 0.491 0.4613 0.4611 *** 5 (199.9) 0.8122 0.8114 0.7626 0.7621 ******************************************************************* **************MODEL******** *node 1, 0.0, 0.0 1001, 1000.0, 0.0 *ngen, nset=nall 1,1001,10 *element, type=b21 1, 1,11 *elgen, elset=eb21 1, 100, 10, 10 *************AQUA********** *aqua -100.0, 100.0, 32.2, 2.0 0., 0., 0., 0. *************MATERIAL/SECTION******* *beam section, elset=eb21, section=circ, material=mat1 3.0, *material, name=mat1 *elastic 4.32e9, *density 14.91, **************BOUNDARY*********** *boundary 1, 1,2, 0.0 1, 6,6, 0.0 **************HISTORY/LOADING******* *restart,write,f=100 **** *step,perturbation,unsymm=no Without added mass *frequency, eigensolver=lanczos, SIM=NO 5, , *OUTPUT,FIELD *MODAL OUTPUT *endstep **** *step,perturbation,unsymm=no With added mass *frequency, eigensolver=lanczos, SIM=NO 5, , *d added mass eb21, fi, 6.0, 1.0 *endstep