RMCRC Project Update

FULL FIELD 3D STRESS &

FATIGUE DAMAGE MEASUREMENT

Professor Rhys Jones

Monash Centre of Expertise Structural Mechanics (CoE-SM)

Email: rhys.jones@monash.edu20/08/2015

A major advantage of this facility is the ability to:

• Rapidly validate finite element designs/analysis

• Rapidly rank and optimise competing designs without the need to perform extensive full scale fatigue testing.

• Assess fatigue performance without the need for a time consuming fatigue test and

• The entire test/evaluation will take less than 1 day

• Designs AND Fitment For Purpose Can be Validated In Unique Purpose Built Full Scale Test Facility

A Unique Full Scale Full Field 3D Stress Measurement Facility

Uses Non Contact Infra-Red Stress Analysis To Validate Measure The Full Field 3D Stresses And Fatigue

Performance Under Load

Background: The change in temperature of a body under load is proportional to the change in stress

DT= -Km.T. Ds

Km = / .a r Cp

=a Linear expansion

= r Density

Cp= Specific heat

= Ds Change in the sum of the principal stressesT is the absolute temperature in KKm is the Thermo-elastic coefficient of material MPa-1

Kelvin’s Law

Thus by measuring the surface temperatures during loading you can determine

a) The stress distribution over the entire structure

b) The fatigue hot spots over the entire structure

Example Stresses and Fatigue Damage in a Rail Sleeper

Australian Standard AS 1085.17—2003 calls for the following test

FIGURE F2 RAIL SEAT REPEATED LOAD TEST RIG ASSEMBLY

A rail seat assembly repeated load test at IRT in the Department of Mechanical and Aerospace Engineering at Monash University

Ability to isolate and quantify the highest stressed region

Ability to locate and quantify the fatigue critical regions without the need for exhaustive and time consuming fatigue tests