No abstract

The delamination phenomenon in sandwich panels occurs in the form of face/core debonding. The grooved foams are usually employed in curved sandwich structures for easier formability and better adhesion. In this research, the debonding toughness of facesheet to the core in a sandwich beam with grooved core is investigated using numerical and experimental methods. The sandwich beam consisted of two Kevlar 49/polyester facesheets and a polyurethane foam core. To obtain the values of strain energy release rate, the Cracked Sandwich Beam (CSB) specimen along with the Modified Beam Theory (MBT) method was used for the data reduction of the test results. In the numerical part, a model based on the cohesive zone theory was employed to simulate the crack growth in the specimens. Comparison of the numerical and experimental load–displacement curves indicated that the proposed model can reasonably predict the behavior of the structure under similar loading conditions. The effect of foam-related parameters such as the number and width of core grooves on crack growth resistance was examined numerically. The results showed that increasing the number and width of the grooves enhanced the resistance of the sandwich beams against the growth of interfacial cracks.

The Greater Tehran area is the most important city of Iran and hosts about 20% of the country population. Despite the presence of major faults and the occurrence of historical earthquakes, nowadays the seismicity is relatively quite low and this enhances the use of simulation methods for microzonation and seismic hazard assessment. To simulate the ground motion caused by the 2009, Mw 4 earthquake, occurred southeast of the city, a hybrid technique is used. It combines two methods: the analytical modal summation and the numerical finite difference, taking advantage of the merits of both. The modal summation is applied to simulate wave propagation from the source to the sedimentary basin and finite differences to propagate the incoming wavefield in the laterally heterogeneous part of the structural model that contains the sedimentary basin. Time and frequency domain parameters are simulated along 2 (E-W and SE-NW) profiles for various stations.