Abstract Polyester pins are incorporated in polyurethane foam filled honeycomb core sandwich panel to increase the interfacial strength between the faces and core in order to improve the performance of sandwich structures. Foam filled Honeycomb Sandwich panel (FHS) and Pin incorporated Foam filled Honeycomb sandwich panels (PFHS) were developed. The developed sandwich panels are tested for flexural and vibration characteristics. The influence of strain rates on flexural behaviour of sandwich panels were also evaluated. The material used for face sheets and pins are same, ends of pin act as chemically cross linked polyester joint at the interfaces of faces and core in addition to the adhesive area. This modification had effectually increased the interfacial strength thereby increased the flexural and damping properties of panels significantly. Moreover, increasing the pin diameter has a larger effect, whereas, the strain rate had a moderate influence on the failure load of both types of sandwich panels. The investigation brings to light a novel pin incorporated foam filled honeycomb sandwich panels that can be used for various applications.

The corrosion inhibition effect of acid extract of the pericarp of the fruit Garcinia mangostana on mild steel in hydrochloric acid medium is studied. Using weight-loss data, corrosion rate (CR) and thermodynamic parameters such as energy of activation for corrosion of mild steel (E), heat of adsorption of the inhibitors on the metal surface (Q) and change in free energy (∆G) are calculated. Adsorption isotherm is also recorded between log C and θ. Electrochemical parameters are evaluated from AC impedance and Tafel polarization studies in the presence and absence of different concentrations of inhibitor. Infra-red spectra are recorded for the extract and the adsorption product to find out the changes in the functional group frequencies of the organic components of the extract. The surface morphological changes are analysed using the SEM images. The entire study shows that the pericarp extract of the fruit G. mangostana is a non-toxic, cost-effective corrosion inhibitor for mild steel in acid medium.