Abstract: The presence, size and location of a crack in a shaft is determined by comparing actual measured natural frequencies of the operating shaft system with the results of an analytical model. From a multi-station analytical model of an uncracked operating shaft system, natural frequencies and associated mode shapes are derived. A suspected axial location of a crack is defined, and a natural frequency of interest is selected which has an associated mode shape exhibiting significant localized bending at the suspected axial location of the crack and at a site of response measurement. The analytical model is modified to include a representation of an asymmetric crack at the suspected crack location. A predicted split and downward shift of a lateral natural frequency of interest as a function of crack depth and/or a predicted downward shift of a torsional natural frequency of interest as a function of crack depth is calculated from the modified model.

Abstract: The presence, size and location of a crack in a shaft is determined by comparing actual measured natural frequencies of the shaft system with the results of an analytical model. From a multi-station analytical model of an uncracked shaft system, natural frequencies and associated mode shapes are derived. A suspected axial location of a crack is defined, and a natural frequency of interest is selected which has an associated mode shape exhibiting significant localized bending at the suspected axial location of the crack and at a site of response measurement. The analytical model is modified to include a representation of an asymmetric crack at the suspected crack location, and a predicted split and downward shift of a lateral natural frequency of interest and/or a predicted downward shift of a torsional natural frequency of interest as a function of crack depth is calculated from the modified model. The actual shaft system is subjected to an excitation force, and vibrational response measurements are taken.

Abstract: An arrangement for mounting a stator assembly (12) of a dynamoelectric machine (10) in a housing (16) employs a plurality of circumferentially distributed mounting supports (56) on the interior of the housing (16) cooperating with pairs of axially aligned radial extensions (54) of the stator assembly (12). Opposed, axially inner faces (62) of paired radial extensions (54) sandwich axially outer end faces (60) of an associated mounting support (56). Threaded fasteners (52) secure the radial extensions (54) to the end faces (60) of the mounting supports (56). Oversized mounting holes (58) in the radial extensions (54) and shims (74) can be used to allow for lateral and axial adjustment, respectively, of the mounted stator assembly (12).

Abstract: A homopolar, transverse pole rotor (14) having a central cylindrical body (24) with a set of circumferentially spaced, axially extending salient poles (28) at each end thereof, is constructed to reduce windage losses. Integral shrouds (29, 31) are placed on either side of each set of salient poles, and a relief is machined into the outer surface of each shroud to form an accentuated pole tip (64) which ensures magnetic centering of the rotor. To further minimize windage losses, the diameter of the central cylindrical body (24) can be reduced, and non-magnetic material can be secured within interpole recesses. Mechanical fasteners (66), dove tails (72) or tensioned circumferential banding (82) can be used to secure the non-magnetic interpole pieces to the rotor.

Abstract: The presence, size and location of a crack in a shaft is determined by comparing actual measured natural frequencies of the shaft with the results of an analytical model. From a multistation analytical model of an uncracked shaft, natural frequencies and associated mode shapes are derived. A suspected axial location of a crack is defined and a natural frequency of interest is selected which has an associated mode shape exhibiting maximum deflection at the supected axial location of the crack and at a site of excitation. The analytical model is modified to include a representation of an asymmetric crack, at the suspected crack location, and the predicted split and downward shift of the natural frequency of interest as a function of crack depth is calculated from the modified model. The actual shaft is subjected to a radial excitation force, and vibrational response measurements are taken with an accelerometer along multiple radial directions.

Abstract: A spool-like stator support structure for an inductor type dynamoelectric machine incorporates stamped, annular end plates. Each end plate has a plurality of spaced-apart recessed landings along its outer edge and, preferably, a plurality of axially outward extending tabs which cooperate to precisely position a plurality of circumferentially distributed generally U-shaped armature elements mounted thereon. The end plate is also provided with a rabbet or press fit along its radially inner edge for mating with an end of the central cylindrical tube of the spool-like support. Cooling ports also distributed about the inner edge of the laminated end plate provide for ventilation of the exterior of said central tube. The end plate can be assembled from a grouping of standardized stampings or from a single stamping.

Abstract: An adjustable speed inductor type rotating dynamoelectric machine, capable of high speed operation, employs a stator assembly incorporating a spool-like support structure. A central, generally cylindrical portion of the support structure supports field windings while radially oriented end portions of the spool-like structure mount and accurately position a circumferentially distributed plurality of C-shaped armature core elements. Radially directed, angularly spaced grooves in the outer surfaces of the end portions receive legs of the C-shaped armature elements and serve to precisely position these elements in three orthogonal directions. The central portion of the armature-field winding support structure may be made of electrically conductive material to provide a flux shield and dissipate heat. For additional ventilation, cooling ports may be provided in the central portion of the spool-like support which cooperate with extended recesses in a coaxial rotor.