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  1. 1. Fig: Tacoma Narrows Bridge (July 1940 to oct,1940) Fig: Missipi river bridge collapse in 2008 (nov,1967 to sep,2008) Spectacular accidents have motivated the community to improve safety
  2. 2. Evolution of materials Reference : American iron and steel institute/U.S department of energy Reference : dallara altairamerica HTC , maya2012
  3. 3.  The advantages of composite structures are that they can be designed to suit the requirements of a specific application or to enhance some properties of the structure such as  Strength and stiffness in desired directions of dominant loads.  corrosion resistance.  desired temperature-dependent behavior . etc
  4. 4.  Composite materials are used in almost all aspects of the industrial and commercial fields in aircraft, ships, common vehicles, medical application , construction etc  Their most attractive properties are the high strength- to-weight ratio and high stiffness-to weight ratio
  5. 5.  These new materials also have some problems such as fiber breakage, matrix cracking, debonding, and delamination.  This damage can cause degradation of strength and overall stiffness for a laminate structure.  The presence of delamination can also significantly reduce the buckling load and compressive strength of the composite laminate
  6. 6. One of the main reason for the failure of the equipment made by composite material is due to fatigue . So S.H.M. is necessary to predicts the life and type of failure in the specimen.
  7. 7.  Structural vibration and acoustics  Electro mechanical impedance  Acoustic emission  Ultrasonic testing Main difficulties to use this techniques are  frequency range and resolution is limited .  Capture signals from other environmental noise while the structure is in operation.  Required completely damp zone.  Testing equipment need to be in contact with the target.
  8. 8.  To overcome these drawbacks, vibration based techniques for a structural health monitoring (SHM) tool use to identify and assess defects.  The key purpose of SHM is to ensure rapid assessment of the health condition of a structure in terms of reliability and safety.  Advantage of vibration base technique  not having contact with the specimen.  remote measurements.  ample frequency response.  high sensibility.  Portability.
  9. 9. F.E.A Experimental values Healthy specimen Damage Specimen (Rectangular notch ) Healthy specimen Damage Specimen (Rectangular notch ) 33.267 33.158 33.750 33.750 231.07 228.36 233.75 230.46 593.46 584.76 595.4 583.75 1144.4 1123.4 1146.4 1126.25
  10. 10.  Its non-destructive testing  Its able to predict the life of the structure.  find the defects present in the structure.  helps in pre-indicate the catastrophically failure.
  11. 11.  Specimen specification Length = 0.220m Width = 0.50mm Damage -Rectangular notch = 0.089mto 0.101m(12mm) Density = 2700kg/m3 Fig: damage by Fractal dimension technique Fig: damage by gapped smoothening technique

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