Method for analyzing vibration damping structure of a tube bundle disposed in a fluid

A method for performing analysis by using a computer device to analyze a vibration damping structure in which a tube bundle disposed in a fluid is supported by a vibration damping member having a plate-like shape disposed in a gap between tubes each having a cylindrical shape included in the tube bundle, the method comprising:

• a model making step of making a FEM model corresponding to the vibration damping structure;
• an error setting step of setting an error parameter for a parameter relating to an element included in the FEM model;
• an analysis step of performing structural analysis by a finite-element method using the FEM model in which the error parameter is set, the finite-element method being repeatedly performed until at least one of a compression load or a bending load acting between the vibration damping member and the tubes is converged to an equilibrium state in the tube bundle;
• and
• using a size tolerance for at least one of the tubes and the vibration damping member of the vibration damping structure based on a result of the analysis step to manufacture the at least one of the tubes and the vibration damping member of the vibration damping structure,
• wherein the FEM model includes
• a first element corresponding to the tube bundle,
• a second element including a one-dimensional element corresponding to the vibration damping member, and
• a third element corresponding to a gap amount between the tube bundle and the vibration damping member,
• wherein the first element includes a plurality of first one-dimensional elements extending to respectively correspond to the tubes included in the tube bundle,
• wherein the second element includes a second one-dimensional element extending along a longitudinal direction of the vibration damping member and a third one-dimensional element extending along a width direction of the vibration damping member,
• wherein the third element includes a pair of gap elements representing a shortest distance between each end of the third one-dimensional element and each first one-dimensional element,
• wherein the error parameter includes a twist amount with respect to an extension direction of the tubes included in the tube bundle, when the vibration damping member is viewed from a cross-sectional direction perpendicular to the longitudinal direction of the vibration damping member,
• wherein the twist amount is a manufacturing error randomly distributed in accordance with a manufacturing tolerance distribution of the vibration damping member;
• wherein the error parameter is set based on data measured on the vibration damping structure,
• wherein the analysis step imposes a loading condition set so that, when the gap amount is less than a predetermined value, a contact force applied to each first one-dimensional element from the second one-dimensional element increases with an increase in interference, and
• wherein the loading condition is defined as a spring load obtained by multiplying a displacement amount applied to a spring by an external force in proportion to the physical interference by a spring constant.