Impact test motor furnished before shipment to determine actual Reed
critical frequency of motor. Include results of impact tests included in
motor test data to be submitted. Pump manufacturer shall address any
discrepancy between calculated and actual motor Reed critical frequency
values to determine whether design changes are required to prevent harmful
natural frequencies in the pump/motor structure. If any design changes are
required, these shall be incorporated at no cost to Government.]
2.5.1.1
[Torsional Analysis
Before pump, gear drive, and engine are released for manufacture, engine
supplier shall analyze the system for harmful torsional natural frequencies
using mass elastic information provided by pump and gear drive
manufacturers. A natural frequency that occurs within 25 percent above or
below [normal operating speed][any of the operating speeds required for
pump operating conditions] is considered to be unacceptable.]
2.5.1.2
[Lateral Frequency Analysis
Before pump, gear drive, and engine furnished under Section(s) [[_____]] [,
] [15133A [DIESEL] / [NATURAL GAS FUELED] ENGINE PUMP DRIVES] [, ] [[_____]
] [, ] [15005A SPEED REDUCERS FOR STORM WATER PUMPS], respectively, are
released for manufacture, pump/gear drive structure shall be analyzed by
pump manufacturer for harmful natural frequencies in the lateral
directions. A natural frequency that occurs within 25 percent above or
below [normal operating speed][any operating speeds required for pump
operating conditions] is considered to be harmful. The dynamic analysis
model shall be constructed using a commercially available program such as
Ansys, Cosmos/M, or equivalent that utilizes finite element methods. The
model shall incorporate effects of column pipes, cover pipes, shafts,
bearings, mass concentrations, and other such features as necessary to
accurately model pump structure. Analyze structure in the run (wet)
condition and consider the effect of water mass in the column and the
damping effect of water in the sump at highest and lowest sump water
levels. The model shall incorporate Reed critical frequency and mass
elastic diagram information provided by gear drive manufacturer. If gear
drive manufacturer cannot demonstrate to the satisfaction of Contracting
Officer (based on impact tests of similar units) that the Reed critical
frequency value is accurate, a dynamic analysis using finite element
methods as described herein shall be conducted by gear drive manufacturer
to determine gear drive Reed critical frequency for use by pump
manufacturer. Submit complete dynamic analysis report including the
following information:
a.
Computer program used.
b.
Schematic diagram of the model depicting nodes and elements.
c.
Input data consisting of node coordinates, element types, material
properties, element characteristics, element connectivities, and
specified displacements.
d.
Gear mass elastic and Reed critical information(or dynamic
analysis, if required).
e.
Analysis results including all significant natural frequencies.
f.
Interpretation of results.
SECTION 15131A
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