Accession Number : ADA291920

Title :   Stress Concentration, Stress Intensity, and Fatigue Crack Growth Along Evacuators of Pressurized, Autofrettaged Tubes.

Descriptive Note : Final rept.,

Corporate Author : ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS

Personal Author(s) : Parker, A. P. ; Underwood, J. H.

PDF Url : ADA291920

Report Date : DEC 1994

Pagination or Media Count : 30

Abstract : A stress analysis has been conducted on a pressurized, fully or partially autofrettaged cylinder with a small diameter evacuator hole penetrating radially through the wall. Pressure was applied on the inside diameter (ID) of the tube, and all or part of this pressure was applied on the evacuator hole surfaces. Total hoop stress concentrations have been determined for a range of radial locations along the evacuator and stress intensity factors have been determined along a crack emanating from the evacuator hole. Fatigue crack growth rates. and hence crack profiles, were predicted at each of the radial locations. These predictions indicate that the critical location for the crack in a non-autofrettaged tube is at the ID, whereas in a fully autofrettaged tube, it is located approximately halfway through the wall thickness. Stress ratio has a significant influence on crack shape in autofrettaged tubes, however, it has a limited effect upon lifetime. The effect of axial residual stresses upon fatigue lifetime due to the autofrettage process has been described and an insignificant reduction in lifetime was a result of such stresses. Finally, the predicted profiles are compared with experimental observations of fatigue crack evacuators, and a limited comparison of predicted and actual lifetimes is presented. Good agreement has been observed in both comparisons. jg

Descriptors :   *CRACK PROPAGATION, *FATIGUE(MECHANICS), *TUBES, *AUTOFRETTAGE, *STRESS CONCENTRATION, RATIOS, THICKNESS, STRESS ANALYSIS, COMPARISON, CRACKS, SHAPE, INTENSITY, RATES, PROFILES, CYLINDRICAL BODIES, RESIDUAL STRESS, PRESSURE, WALLS, RADIAL FLOW.

Subject Categories : Pumps, Filters, Pipes, Tubing, Fittings & Vlvs
      Machinery and Tools
      Ballistics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE