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Theoretical aspects of a new capability developed and implemented in NASTRAN Level 17.7 to analyze forced vibration of a cyclic structure rotating about its axis of symmetry are presented. Fans, propellers, and bladed shrouded disks of turbomachines are some examples of such structures. The capability includes the effects of Coriolis and centripetal accelerations on the rotating structure which can be loaded with: 1) directly applied loads moving with the structure and 2) inertial loads due to the translational acceleration of the axis of rotation (“base” acceleration). Steady-state sinusoidal or general periodic loads are specified to represent: 1) the physical loads on various segments of the complete structure, or 2) the circumferential harmonic components of the loads in (1). The sinusoidal loads are specified as functions of frequency and the general periodic loads are specified as functions of time. The translational acceleration of the axis of rotation is specified as a function of frequency in an inertial coordinate system. The cyclic symmetry feature of the rotating structure is used in deriving and solving the equations of forced motion. Consequently, only one of the cyclic sectors is modelled and analyzed using finite elements, yielding substantial savings in the analysis cost. Results, however, are obtained for the entire structure. A tuned twelve-bladed disk example is used to demonstrate the various features of the capability.

No abstract

The general trend in the field of machine tools is to increase the speed of feed axes with the aim of reducing manufacturing times, high speed machining is a significant example of such increase. Ball screws have proven their ability to fulfill requirements of workpiece positioning accuracy, nevertheless, the heat generated in the screw-nut interaction increases proportionally with the speed of the axes. As a result, an increase in temperature takes place, which causes thermal expansion of the ball screw, producing positioning errors and decreasing the service life of the ball screws, therefore it is important to have effective methods for predict the temperature.The main objective of the present work is to predict the heat generated in the screw-nut contact based on analytical models in order to estimate the temperature distribution in the nut. For this purpose a heat transfer FE model of a preloaded high speed ball screw nut has been developed. Additionally, experimental heating tests have been performed to validate the FE numerical model. In this way, the temperature predictions obtained at different working conditions have less than 6% of deviation comparing with the experimental results.

When Government drawings, specifications, or other data are used for any purpose other than in connection with a definitely related Government procurement operation, the United States Government thereby incurs no responsibility nor any obligation whatsoever; and the fact that the government may have formulated, furnished, or in any way supplied the said drawings, specifications, or other data, is not to be regarded by implication or otherwise as in any manner licensing the holder or any other person or corporation, or conveying any rights or permission to manufacture, use or sell any patented invention that may in any way be related thereto. E WI 0Mi SSUITSUAALW M 1 'IM1. AVAIL as/or Copies of this report should not be returned unless return is required by security considerations, contractiual obligations, or notice on a specific document. 400-un 1971-CO0S-43-71.745 ~ I UNCLASSIFIED Security Classification DOCUMENT CONTROL DATA-R&D (Security cassiicat~oA *I title. body of absacnt and indexing arthlon rnuxte on.ni d when the nvaeb2Irpor oflilahsdild) I OIRIiNATIN S ACTIVITY (corporte author.) 2 CO1TSCPT ASPCT UNCLASS IFIED BuffaloL New York _____________NIA 3REPORT TITLE MAGIC II-An Automated General Purpose System for Structural Analysis Volume III-Programmer's Manual 4. DESCRIPTIVE NOTES (Tyvpe ot report and inclusive dotes) 9. AUTHOR(S) fLast narme. first name. initial) A. Michael Gallo Q~. REPORT OAT2 7a. TOTAL NO. OF PAGES 7b. NO. OF REFS-May 19 7 1'-361__ _ _ _ _ _ 5-iNone _ _ _ _ I;e. CONTRACT OR GRANT No. Sa. ORIGINATOR'S REPORT NUMSER(S) ' tional elements include a frame element, quadrilateral plate and triangular plate elements which can be used for both stress and stability analysis. The finite elements listed include matrices for~ stiffness, mass, incremental stiffness, prestrain load, thermal load, distributed mechanical load and stress.