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SUMMARY:Smart structures using Shape Memory Alloys - Professor Kamal Bajor
 ia
DTSTART:20180615T140000Z
DTEND:20180615T150000Z
UID:TALK106891@talks.cam.ac.uk
CONTACT:Karen Mitchell
DESCRIPTION:Solid to solid phase transformation is a unique feature of Sha
 pe Memory Alloys (SMA) which makes it popular for many applications. Large
  recoverable strain\, super elasticity and shape memory effect are the cha
 racteristics which make Ni-Ti an extraordinary material for structures to 
 control seismic response. Two phases of this material Austenite and Marten
 sitic have two different crystalline forms showing different behaviors in 
 these phases. The phase transformation is attained by change in temperatur
 e or stress. SMA is able to revert back to its original shape and recover 
 residual strains by transforming its phase using temperature change. Shape
  memory effect of two different alloys NiTi and Fe based SMA is used to en
 hance the structural properties of a steel Moment Resisting Frame as well 
 as a RCC structure.\nThe yielded steel beams need to be treated after the 
 occurrence of earthquake. Shape memory alloy is proposed to be used at pla
 stic hinge regions to recover the deflection due to its super elasticity p
 roperty\, thus creating a ‘psudo plastic hinge’\, one capable of under
 going large strains and recovering them completely with no residual strain
 . Structural behavior of a steel frame with Shape Memory Alloy at beam col
 umn connection has been studied for lateral loading. Also the response of 
 the frame was checked for time history analysis using past earthquake data
 . Comparison of the time history analysis response of bare frame (Steel on
 ly connections) and frame with use of SMA at connection suggested excellen
 t performance of frame equipped with SMA. To check the performance of the 
 frame for loading unloading cycle\, incremental lateral loading is applied
  to the frame up to maximum load and then it is unloaded completely.  The 
 SMA equipped frame shows significant recovery of the residual displacement
 . The reduction in residual displacement of the SMA equipped frame is also
  seen in case of time history analysis. Though Ni-Ti SMAs show a little mo
 re recovery in residual displacement\, cost comparison shows using Fe base
 d SMA in Civil Engineering industry will be beneficial for the maximum uti
 lization of material with lesser cost.\nIn the concrete structures reinfor
 ced with conventional steel\, the earthquake energy dissipation is provide
 d through yielding of reinforcement and plastic deformation. Shape memory 
 alloy (SMA) is considered as a replacement to conventional steel reinforce
 ment. Pushover analysis is carried out for a Reinforced Concrete moment re
 sistance frame with the traditional steel reinforcement replaced partially
  with Nickel-Titanium (Nitinol) SMA. Partial replacement of traditional st
 eel reinforcement by SMA shows better performance.\n
LOCATION: Cambridge University Engineering Department\, LT6
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