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MARAXIL
http://maraxil.mecc.polimi.it
WP2 – Residual stresses measurements
Progetto cofinanziato da Regione Lombardia tramite il "Fondo per la promozione di Accordi istituzionali", attraverso il quale il progetto Maraxil è stato cofinanziato nell'ambito del Bando Cooperazione Scientifica e Tecnologica.
1. Abstract
The state of residual stress induced by deep rolling in a full scale train
axle was investigated in the present work. Both X-ray diffraction method
and hole drilling technique were applied to measure surface and in depth
distribution of residual stress.
2. XRD Experimental Procedure
Three different lines along the axis of axle were considered for the
measurements. The angular positions of lines were 0º, 120º and 240º. 18
different points along these lines were considered for the measurements
(Fig. 1).
Fig. 1. drawing of axle with measurement points and lines.
Surface residual stress was measured at all points (1-9, 12-20) using X-
Stress 3000 Stress Tech. diffractometer. At each point residuals stress was
measured in longitudinal (direction 0º), circumferential (direction 90º)
and third direction of 45º. Fig. 2 illustrates the Configuration of axle and
X-ray diffractometer during measurement.
Fig. 2. Configuration of axle and diffractometer during measurement.
In depth residual stress was also measured by X-ray at some points:
Line1:Points 14,16. Line2: Points 4,12. Line3: Points 4,12,14,16.
Depth (mm)
0.0 0.5 1.0 1.5 2.0 2.5
Res
idu
al
Str
es
s (
MP
a)
-1000
-800
-600
-400
-200
0
200
Direction 0o
Direction 45o
Direction 90o
Second Principal Stress
Third Principal Stress
Distance along axis (mm)
0 500 1000 1500 2000
Re
sid
ual S
tres
s (
MP
a)
-1000
-800
-600
-400
-200
0
200
Direction 90o
Direction 45o
Direction 0o
Second Principal
Third Principal
3. XRD Results
Fig.3 and Fig. 4 illustrate Surface residual stress along line 3 and in
depth distribution of residual stress for point 14 of line 1. The same
trends were also observed for other measurements points.
Fig. 3. Surface residual stress.
Fig. 4. In depth residual stress distribution.
Not Rolled
4. Hole drilling measurements
Residual stresses due to cold-rolling were also measured by the hole
drilling method in sections A, B, C and D of the axle at 0°, 120° and
240°
As it can be seen, the entity of compressive residual stresses is
significantly high and vanishes at a depth equal to about 2 mm
Section C Section D
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