Strain Age Control - formulone.redaelli.comformulone.redaelli.com/papers/Strain Age Control.pdf ·...
-
Upload
dangnguyet -
Category
Documents
-
view
216 -
download
1
Transcript of Strain Age Control - formulone.redaelli.comformulone.redaelli.com/papers/Strain Age Control.pdf ·...
25/07/2016 3
External actions
TENSILE + BENDING STRESS(load, D/d ratio, cycles)
INCREASE OF TEMPERATURE
(load, friction, AHC, cycles)
Today we speck about these 2 main influencing parameters
Which elements are in common in all the applications?
25/07/2016
Basic concepts on wire fatigue
T T
s
sm
t
Tensile stress
But we are not satisfied: we want to stress more our wire…
Medium Stress
sa
s
t
T T
s
sm
t
T Tsm
sa
s
t
Bending moment
Tensile stress
M M
M M
Basic concepts on wire fatigue
If we combined the 2 actions
• The axial load generates sliding planes on
45°• The bending moment generates high
surface tensions inducing crystal plane
protrusion
T, M
Sliding planes
T, M
T, MT, M
Sliding planes
Basic concepts on wire fatigueWhat’s the process behind the wire break for fatigue?
Hardening effect on Ductil – Brittle transition after cyclic
alternate loads
Drawn wire Stress-Strain curve
Cumulate Energy before
failure
sm
sa
s
t
If tensile stress +
Bending stress are
applied
TENSILE +
BENDING
STRESS
High Hardening
Softening
25/07/2016 9
s
t
s
t
Hardening effect on Ductil – Brittle transition after cyclic alternate loads
High Hardening
Softening
What about the rope?
25/07/2016 10
T
D: Sheave Diameter
d: Rope diameter
sm
sa
sm medium Stress
T
sm
sa
s
t
if D decreases:
sa increases
sa =
D sheave
d rope
E
TENSILE + BENDING STRESS(load, D/d ratio, cycles)
25/07/2016 11
?
External actions
How many of you think the temperature monitoring is important?
And why?
Maybe because of the lubricant preservation?
Not exactlyWhat about the steel properties?
INCREASE OF TEMPERATURE
(load, friction, AHC, cycles)
If Temperature increases
s
e
Agt: Elongation
What if heating acts on wire?
High RP02 – Rm difference
Low RP02 – Rm difference
Equivalent RP02,Rm
25/07/2016 13
What if heating acts on wires?
1500
1600
1700
1800
1900
2000
2100
2200
0 25 50 75 100 125 150 175
RP
02
-R
m M
Pa
T° C
RP02-Rm
Still convinced we can extend the life time of the ropes just developing high temperature resistance lubricant?
25/07/2016 16
25/07/2016 17
What’s important in all of this?
Few furthers considerations:We can develop• continuous monitoring systems (no matter is the Technology)• Diagnostic systems (MRT, LMA)• High temperature lubricant resistance
But
If we do not keep in mind what is the limit of utilization of
the raw material we can just wait until some problem to
occur before we can detect it
Redaelli Development STAY TUNEDThermal status of the rope under given
conditions
- Thermal gradient acquisition
inside/outside the rope
- Correlation between the 2 values in
transient and steady state status
- Definition of Redaelli Mathematical
model
- Devices