DETERMINATION OF THE DRIVING FORCE FOR CRACK INITIATION FROM ACOUSTIC RECORDS OF G SUB C TESTS ON HIGH-STRENGTH METALS FOR ROCKET MOTOR CASINGS

Abstract

Fracture instability tests with a double-inking procedure were employed with the center-notched G sub c, test specimen to establish conditions at crack initiation. With this information anACOUSTIC METHOD WAS USED TO DETER INE THE DRIVING FORCE G* sub Nc required to initiate cracking from a machined notch. The audio instrumentation can be added to the G sub c test without affecting standard procedure. Tests with recuded length of starting slot indicated that G* sub Nc for a given type of notch is a relatively constant material property similar to the critical G sub c* value for fast fracture. The G* sub Nc value can be used in fracture toughness equations for the motor case to predict a slot size at which cracking should just initiate in a single cycle of stressing the material to yield strength. The general equivalence of K* sub Nc to K sub Ic was an indication of adequate notch sharpness. (Author)

Document Details

Document Type
Technical Report
Publication Date
Oct 04, 1961
Accession Number
AD0263911

Entities

People

  • H.e. Romine

Organizations

  • Naval Surface Warfare Center Dahlgren Division

Tags

Communities of Interest

  • Weapons Technologies

DTIC Thesaurus Topics

  • Equations
  • Fast Fractures
  • Instability
  • Instrumentation
  • Materials
  • Mechanical Properties
  • Physical Properties
  • Rocket Engines
  • Rockets
  • Sharpness
  • Standards
  • Toughness
  • Yield Strength

Readers

  • Combustion and Flow Dynamics.
  • Materials Science (Mechanical Engineering).
  • Naval Engineering and Maritime Security