Failure analysis of a tool-steel torque shaft

Conference · Thu Jan 01 00:00:00 EST 1981

OSTI ID:5834723

Reagan, J R

A low design load drive shaft from an experimental diesel truck engine failed unexpectedly during highway testing. The shaft was driven by a turbine used to deliver power from an experimental exhaust heat recovery system to the engine's crankshaft. During design, fatigue was not considered a major problem because of the low operating cyclic stresses. An independent testing laboratory analyzed the failure by routine metallography. The structure of the hardened S-7 tool steel shaft was banded and the laboratory attributed the failure to fatigue induced by a banded microstructure. NASA was asked to confirm this analysis. Visual examination of the failed shaft plus the knowledge of the torsional load that it carried pointed to a 100% ductile failure with no evidence of fatigue. Scanning electron microscopy confirmed this. Torsional test specimens were produced from pieces of the failed shaft and torsional overload testing produced identical failures to that which had occurred in the truck engine. This pointed to a failure caused by a high overload and although the microstructure was defective it was not the cause of the failure.

• Research Organization: National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
• DOE Contract Number: AI01-76CS51011
• OSTI ID: 5834723
• Report Number(s): DOE/NASA/1011-35; NASA-TM-82758; CONF-811149-1; ON: DE82004300
• Resource Relation: Conference: Conference on deformation, fracture, wear, and nondestructive evaluation of materials, New Orleans, LA, USA, 23 Nov 1981
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
42 ENGINEERING
36 MATERIALS SCIENCE
DIESEL ENGINES
SHAFTS
FAILURES
TORSION
STEELS
MATERIALS TESTING
TRUCKS
EXPERIMENTAL DATA
FAILURE MODE ANALYSIS
MICROSTRUCTURE
ALLOYS
CRYSTAL STRUCTURE
DATA
ENGINES
HEAT ENGINES
INFORMATION
INTERNAL COMBUSTION ENGINES
IRON ALLOYS
IRON BASE ALLOYS
MACHINE PARTS
NUMERICAL DATA
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TESTING
VEHICLES
330603* - Vehicle Design Factors- Engine System
420500 - Engineering- Materials Testing
360102 - Metals & Alloys- Structure & Phase Studies
360103 - Metals & Alloys- Mechanical Properties