Abstract: Wave propagation based automatic structural health monitoring techniques and the warning-alert systems are widely adopted in aerospace and nuclear industry. These techniques are however, not in a matured state of development for civil structures and are evolving. Hence research in this area is of paramount importance. This paper deals with axial wave propagation in concrete beam with structural dis-continuities. Dis-continuity (impedance mismatch) is induced in the beam by varying its cross section area along its length. Numerical simulations are performed using the spectral finite element method (SFEM) and compared with experimental studies conducted on four different concrete beams using instrumentation for Pulse echo configuration and Pitch catch configuration methods.

• Publication Date: 25-May-2014
• DOI: 10.15224/978-1-63248-028-6-03-86
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Abstract: The experimental studies for determining the flexural properties of thermo set rigid polyurethane unfilled foam core – glass/epoxy skin sandwich composites, are presented here. Sandwich composites were fabricated in the shape of panels by using glass fabric/epoxy as the skin material and rigid polyurethane foam (PUF) as the core. PUF materials of 125 & 250 kg/m3 foam densities with 3:1 & 4:1 skin to core weight ratios were fabricated separately using the vacuum bagging technique. The sandwich panels were tested at different span to depth ratios. The flexural properties like the bending strength, flexural rigidity, shear stress, shear deflection and shear strain were evaluated and a detailed analysis made on the influence of foam densities and different span to depth ratios on the fracture behaviour of these sandwich composites in flexure. Due comparisons have been made on the flexural behaviour with other foams also.

• Publication Date: 25-May-2014
• DOI: 10.15224/978-1-63248-028-6-03-87
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