Mechanical vibration characteristics of bell-type pump mountings
This thesis describes an analytical and experimental study to
determine the mechanical characteristics of the pump mounting,
bell housing type. For numerical purposes, the mount was modelled
as a thin circular cylindrical shell with cutouts, stiffened
with rings and stringers; the boundary conditions were considered
to be either clamped-free or clamped-supporting rigid heavy mass.
The theoretical study was concerned with both the static response
and the free vibration characteristics of the mount. The approach
was based on the Rayleigh-Ritz approximation technique using beam
characteristic (axial) and trigonometric (Circumferential)
functions in the displacement series,
Love - Timoshenko thin shell theory.
determine the effect of the supported
in association with the
Studies were carried out to
heavy mass on the static
response, frequencies and mode shapes; in addition, the effects
of stringers, rings and cutouts on vibration characteristics
were investigated. The static and dynamic formulations were
both implemented on the Hewlett Packard 9845 computer. The
experimental study was conducted to evaluate the results of the
natural frequencies and mode shapes, predicted numerically. In
the experimental part, a digital computer was used as an
experiment controller, which allowed accurate and quick results.
The following observations were made:
1. Good agreements were obtained with the results of other
2. Satisfactory agreement was achieved between the theoretical
and experimental results.
3. Rings coupled the axial modal functions of the plain cylinder
and tended to increase frequencies, except for the torsion
modes where frequencies were reduced. Stringers coupled the
circumferential modal functions and tended to decrease
frequencies. The effect of rings was stronger than that of
4. Cutouts tended to reduce frequencies; in general, but this
depends on the location of the cutouts; if they are near
the free edge then an increase in frequencies is obtained.
Cutouts coupled both axial and circumferential modal
5. The supported heavy mass had similar effects to those of the
rings, but in an exaggerated manner, particularly in the
reduction of torsion frequencies.
6. The method of analysis was found to be a convenient
analytical tool for estimating the overall behaviour of the
s6ell with cutouts.
Proposals are offered regarding further relating work.
Key words: Pump mounting ~ Shells 1 Rayleigh-Ritz ~ C.A.D.