Post on 14-Mar-2018
Shape Memory Alloys in Structural Vibration ControlResearch at UNIC/DEC/FCT/UNL
Corneliu Cismasiu & Filipe Pimentel Amarante dos Santos
Centro de Investigacao em Estruturas e Construcao - UNICFaculdade de Ciencias e Tecnologia
Universidade Nova de Lisboa
C60 - CONFERINTA INTERNATIONALA “Constructii 2013”
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 1 / 30
Shape Memory Alloys (SMAs)
Metallic alloys exhibiting two peculiar thermo-mechanical properties:
◮ shape memory effect – allows the material to recover its original geometrythrough a heat cycle, after withstanding large deformations;
◮ superelasticity – enables the material to recover from large nonlinear strainsduring a mechanical cycle of loading and unloading, while dissipating aconsiderable amount of energy through hysteresis.
Five primary alloy families are of interest in civil engineering aplications: the nickel-titanium family (Nitinol), the iron-magnesium-silicon alloys, two copper-based families,the cooper-zinc-aluminum-nickel and the copper-aluminium-nickel, and some specialstainless steel formulations.
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 2 / 30
Shape memory effect
The sample is deformed (A to B) and unloaded (B to C) at a temperature below Mf.The residual deformation is restored during heating to a temperature above Af.
(Mf – martensite finish temperature, Af – austenite finish temperature, Mf < Af )
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 3 / 30
Shape memory effect - civil engineering applications
Smart prestressing of the bridge carrying
Sherman Road over US-31 [NCHRP-96-IDO29]
Shear cracks on beam stem Heating of SMA rods
Rehabilitation of a concrete structure using
intelligent materials [Soong et al ., 2006]
During loading After heating the crack closes up
Self-repairing performance of concrete elements using superelastic SMA wires, smartprestressing, RC beams with variable stiffness and strength, health monitoring andrehabilitation of concrete structures, self actuating fuse for auto-adaptive compositestructures.
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 4 / 30
Superelasticity
The sample is strongly deformed at relatively low stresses (A to B) at a temperatureabove Af. During subsequent unloading a complete shape recovery occurs (B to C).
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 5 / 30
Superelasticity - civil engineering applications
Seismic protection of cultural heritage structures
Basilica of St. Francis of Assisi [Croci, 2001]
S.Giorgio Church Bell-Tower [Indirli et al., 2001]
St. Feliciano Cathedral [Castellano et al., 2000]
Research project:
◮ ISTECH - Shape Memory Alloy
Devices for Seismic Protection of
Cultural Heritage Structures
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 6 / 30
Superelasticity - civil engineering applications
Superelastic restrainers and connectors
[Johnson et al., 2008]
[Padgett et al., 2009] [Ocel et al., 2004]
Research projects:
◮ NEES Payload Project - Large-scaleexperimental evaluation of shape
memory alloy bridge cable restrainers
◮ MANSIDE - Memory Alloys for New
Seismic Isolation and Energy
Dissipation Devices
◮ SUPERB - Seismic Unseating
Prevention. Elements for Retrofitting
of Bridges
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 7 / 30
Superelasticity
σ
εA
D
B
C
Transformations in the crystaline structure:
◮ forward transformation (A → M) – curve ABC
◮ inverse transformation (M → A) – curve CDA
hysteretic cycle null residual deformations⇓ ⇓
energy dissipation repositioning capability⇓ ⇓
Vibration control devices based on superelastic SMAs
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 8 / 30
SMA - temperature and strain rate independent constitutive models
The constitutive model is characterised by the austenitic elastic modulus, the strainassociated with the transformation process and the starting and final stresses duringthe forward and inverse transformations.
ε [%]
σ [MPa]
ExperimentalNumerical
0
50
100
150
200
250
300
350
400
450
70 1 2 3 4 5 6
Complete cycle followed by a small inner cycle
ε [%]
σ [MPa]
70 1 2 3 4 5 60
50
100
150
200
250
300
350
400
450
ExperimentalNumerical
Three complete cycles of decreasing amplitude
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 9 / 30
SMA - temperature and strain rate dependent thermo-mechanical models
As the strain rate increases, the SMA wires can no longer expel the internal heatgenerated during the loading phase and absord heat from its environment duringthe unloading phase and therefore the constitutive model must relate stress, strain,austenite fraction and the temperature in the material.
Transformedphase
M A
Mechanical law Exponential kinetic law
10
20
40
60
80
100
30
50
70
90
Heat balance equation
The model couples the constitutive relations, a kinetic law that describes the volumefraction of austenite and a balance equation that considers the thermal effects on thematerial ⇒ reliable constitutive model even for high strain rates.
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 10 / 30
SMA - temperature and strain rate dependent thermo-mechanical models
T = 10◦C f = 0.02Hz
Experimental
Numerical
100
200
300
400
500
600
700
800
00 1 2 3 4 5 6 7 8
ε [%]
σ [MPa]
T = 20◦C f = 0.02Hz
0 1 2 3 4 5 6 7 8
100
200
300
400
500
600
700
800
0
Experimental
Numerical
ε [%]
σ [MPa]
T = 10◦C f = 0.1Hz
Experimental
Numerical
100
200
300
400
500
600
700
800
00 1 2 3 4 5 6 7 8
ε [%]
σ [MPa]
T = 20◦C f = 0.1Hz
Experimental
Numerical
0 1 2 3 4 5 6 7 8
100
200
300
400
500
600
700
800
0ε [%]
σ [MPa]
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 11 / 30
Strain rate analysis using thermo-mechanical model
10000 200 400 600 800 10000 200 400 600 800 10000 200 400 600 8000
10
20
30
40
50
0
10
20
30
40
50
0
10
20
30
40
50
σ [MPa]
f = 0.001 Hz
time [s]
ε [%]
T [◦C]
ε [%]
σ [MPa]
f = 10 Hzf = 0.1 Hz
σ [MPa]
ε [%]
T [◦C]
time [s]
T [◦C]
time [s]
0 1 2 3 4 5 76 0 1 2 3 4 5 76 0 1 2 3 4 5 760
100
200
300
400
500
600
0
100
200
300
400
500
600
0
100
200
300
400
500
600
Dissipated energy
f [Hz]
W /W0.001
0.95
0.90
0.85
0.80
0.75
1.00
0.001 100.01 0.1 1
Pseudostatic load → Dynamic load
Room Temperature = 20◦C
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 12 / 30
Cycling effects - experimental tensile tests
Evolution of:
◮ Cummulative creep deformation;
◮ Critical stress to inducemartensite;
◮ Strain associated to thetransformation.
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 13 / 30
Cycling effects - experimental validation of the numerical model
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 14 / 30
Superelastic SMA based oscillators
u(t)
p(t)
m
SE
m
u(t)
p(t)
SE1 SE2
m
u(t)
p(t)
SE1
SE2
SE3
◮ simple SMA wire
◮ two pre-tensioned wires working inphase oposition
◮ two pre-tensioned wires withre-centring element
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 15 / 30
Simple SMA wire (T = 20◦C, f = 2 Hz)
Exhibits:
◮ self-recentring
◮ low energydissipation(ζeq ≃ 8%)
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 16 / 30
Two pre-tensioned wires working in phase oposition (T = 20◦C, f = 2 Hz)
Exhibits:
◮ good energydissipation(ζeq ≃ 15%)
◮ noself-recentring
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 17 / 30
Two pre-tensioned wires with re-centring element (T = 20◦C, f = 2 Hz)
Exhibits:
◮ good energydissipation(ζeq ≃ 15%)
◮ self-recentring
↓
appealing propertiesfor seismic control
devices
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 18 / 30
Drawbacks of SMA based passive control devices
◮ Re-centring capabiliy implies a third elastic element;
◮ Relaxation can not be avoided, as the use of permanent pre-strained SE wires isa must in order to obtain competitive damping ratio;
◮ Cumulative creep can be avoided by keeping the strains inside a so calledpseudo-elastic window, which ensures appropriate material behaviour, but this isa very challenging task when dealing with arbitrary seismic excitations.
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 19 / 30
Proposed semi-active device
1 2 3 4 5 6 87 9
t
u
SE2
SE1
General behaviour of the proposed semi-active control system
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 20 / 30
Sao Martinho railway viaduct
Legend: 1. SMA device, 2. Abutment, 3. Transverse girder, 4. Main girder
For the longitudinal analysis, the viaduct is assimilated to a 1DOF dynamic system:4650 ton mass, 355×103 kN/m stiffness and 5% structural damping.
Two passive control devices are placed at the two ends of the viaduct, one for eachmain girder. The devices consist of two sets of 1.0 m SMA wires, each set with atotal area of 1963 mm2 (bars or a set of smaller wires laid parallel in strands, to forma cable).
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 21 / 30
Response of the structure to “El Centro” earthquake
DISPLACEMENT TIME HISTORYUNCONTROLLED
[s]
[cm] DISPLACEMENT TIME HISTORYPASSIVE CONTROL
[s]
[cm] DISPLACEMENT TIME HISTORYSEMI−ACTIVE CONTROL
[s]
[cm]
ACCELERATION TIME HISTORYPASSIVE CONTROL
[s]
[m/s2] ACCELERATION TIME HISTORYSEMI−ACTIVE CONTROL
[s]
[m/s2]ACCELERATION TIME HISTORYUNCONTROLLED
[s]
[m/s2]
−8
−6
−4
−2
0
2
4
6
8
0 10 20 30 40 50−8
−6
−4
−2
0
2
4
6
8
0 10 20 30 40 50−8
−6
−4
−2
0
2
4
6
8
0 10 20 30 40 50
−8
−6
−4
−2
0
2
4
6
8
0 10 20 30 40 50−8
−6
−4
−2
0
2
4
6
8
0 10 20 30 40 50−8
−6
−4
−2
0
2
4
6
8
0 10 20 30 40 50
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 22 / 30
Response of the structure to “El Centro” earthquake
STRAIN TIME HISTORYPASSIVE CONTROL
21
[%]
[s]
STRAIN TIME HISTORYSEMI−ACTIVE CONTROL
21
[%]
[s]
SE SE
0
1
2
3
4
5
6
7
8
0 10 20 30 40 50 0
1
2
3
4
5
6
7
8
0 10 20 30 40 50
SE SE
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 23 / 30
Response of the structure to “Kobe” earthquake
DISPLACEMENT TIME HISTORYUNCONTROLLED
[s]
[cm]
2
DISPLACEMENT TIME HISTORYPASSIVE CONTROL
[s]
[cm] DISPLACEMENT TIME HISTORYSEMI−ACTIVE CONTROL
[s]
[cm]
ACCELERATION TIME HISTORYUNCONTROLLED
[s]
[m/s2]
2
[s]
[m/s2] ACCELERATION TIME HISTORYPASSIVE CONTROL
ACCELERATION TIME HISTORYSEMI−ACTIVE CONTROL
[s]
[m/s2]
−20
−10
0
10
20
0 10 20 30 40 50 60
failure in SE
−20
−10
0
10
20
0 10 20 30 40 50 60
−20
−10
0
10
20
0 10 20 30 40 50 60
−20
−10
0
10
20
0 10 20 30 40 50 60
failure in SE
−20
−10
0
10
20
0 10 20 30 40 50 60
−20
−10
0
10
20
0 10 20 30 40 50 60
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 24 / 30
Response of the structure to “Kobe” earthquake
STRAIN TIME HISTORYSEMI−ACTIVE CONTROL
21
STRAIN TIME HISTORYPASSIVE CONTROL
21
[%]
[s][s]
[%]
2
0
2
4
6
8
10
0 10 20 30 40 50 60
SE SE
SE SE
0
2
4
6
8
10
0 10 20 30 40 50 60
failure in SE
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 25 / 30
Experimental prototype
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 26 / 30
Experimental prototype under harmonic load
30
25
20
15
10
5
00 10 20 30 40 50 60 70 80 90
Setpoint highPID threshold highPID threshold low
Setpoint lowForce
Accumulated force
CONTROL-ONCONTROL-OFF
PID-ON
PID-OFF
PID-ON
F[%Fmax ]
t[s]
Force time-history in a SMA wire
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 27 / 30
Experimental prototype under harmonic load
20
15
10
5
0
-5
-10
-5 0 5 10 15
1
2
F[%Fmax ] Initial cycle
Final cycleu[mm]
Force-displacement diagram
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 28 / 30
Conclusions regarding the proposed semi-active device
◮ The strain accumulation in the wires is a result of the motion of the structureitself, with no need of external energy input in the system;
◮ With no need of initial pre-strain calibration, the device responds well to virtuallyany level of dynamic excitation;
◮ It presents important damping capabilities, is able to confine the strains in theSE wires inside recoverable limits to minimise the rheological effects related tocumulative creep, and finally, at the end of the action, is able to recover the SEwires strain free condition exhibiting efficient re-centring capabilities andavoiding relaxation problems;
◮ Is able to confine force values throughout the entire duration of the seismicaction, meaning that the force the semi-active device transmits to the structurecan be conveniently bounded.
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 29 / 30
Shape Memory Alloys in Structural Vibration ControlResearch at UNIC/DEC/FCT/UNL
Corneliu Cismasiu & Filipe Pimentel Amarante dos Santos
Centro de Investigacao em Estruturas e Construcao - UNICFaculdade de Ciencias e Tecnologia
Universidade Nova de Lisboa
C60 - CONFERINTA INTERNATIONALA “Constructii 2013”
C. Cismasiu & F.P. Amarante dos Santos (C60, 2013) SMAs in Structural Vibration Control 30 / 30