Optimal correction of mass and stiffness matrices using measured modes

Abstract

Discussion of Results The equations of motion were numerically integrated utilizing a total of 36 elements to define the geometry of the corer. The corer was allowed to free-fall for 3 s, at which time the global variables had the following values: u = 23.6 m/s, w = 2.3 m/s, 4 = 0.05 rad/s, 6 = 6.4 deg, ^=-0.8 m, Ze = 31.0 m. The corer assumed an elongated inverted-S shape. At ^ = 3 s, maximum bending moments occurred at the location of the step taper and at the junction between the afterbody and the upper portion of the barrel. The local element deflection, slope, and bending moment at these locations are given in Table 1 and are approximate due to the local variables being measured at discrete locations along the length of the corer. It is unlikely that the corer will actually experience such large bending moments during free-fall. However, it is intuitive that large bending moments will occur at the barrel/afterbody junction and may even become larger during penetration.