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Honeycomb sandwich structures are increasingly used in the automotive, aerospace and shipbuilding industries where fuel savings, increase in load carrying capacity, vehicle safety and decrease in gas emissions are very important aspects. The aim of this study was to develop the theoretical methods, initially proposed by the authors and by other researchers for the prediction of low-velocity impact responses of sandwich structures. The developed methods were applied to sandwich structures with aluminium honeycomb cores and glass-epoxy facings for the assessment of impact parameters and for the prediction of limit loads. The values of model parameters were compared with data reported in literature and the predictions of the limit loads were validated by means of the experimental data. Good achievement was obtained between the results of the theoretical models and the experimental data. The failure mode and the internal damage of the sandwich panels have been investigated using 3D computed tomography, which allowed the evaluation of parameters of energy balance model, and infrared thermography, which allowed the detection of the temperature evolution of the specimens during the tests. The experimental and theoretical results demonstrated that the use of glass-epoxy reinforcement on aluminium honeycomb sandwiches enhances the energy absorption and load carrying capacities.

The joining techniques of lightweight and strong materials in the transport industry (e.g. automotive, aerospace, shipbuilding industries) are very important for the safety of the entire structure. In these industries, when compared with other joining methods, the use of adhesively bonded joints presents unique properties such as greater strength, design flexibility, and reduction in fuel consumption, all thanks to low weight. The aim of this study was the analysis of the tensile fatigue behavior of adhesively bonded glass fiber/epoxy laminated composite single-lap joints with three different specimen types including 30, 40 and 50 mm overlap lengths. In this study, composite adherents were manufactured via vacuum-assisted resin transfer molding and were bonded using Loctite 9461 A&B toughened epoxy adhesive. The effect of a surface treatment method on the bonding strength was considered and it led to an increment of about 40%. A numerical analysis based on a finite element model was performed to predict fatigue life curve, and the predicted results showed good agreement with the experimental investigation.

One of the main focuses in transportation engineering is the application of sandwich materials in order to create safer and efficient vehicles. The main focus of this study was the application of 3D computed tomography for analyzing the responses of sandwich panels with micro lattice core subjected to impact loading. Micro lattice specimens were manufactured using Ti-6Al-4V powder by means of a direct metal laser sintering system. A theoretical model was applied for predicting the failure initiation loads under impact loading. The predictions presented good consistency with the experimental measurements. The 3D computed tomography system was used for the analysis of the collapse modes of the micro lattice sandwich panels after low-velocity impact tests. Experimental and theoretical results proved that lightweight sandwich panels with micro lattice cores are excellent energy absorbers and, therefore, they could have significant applications in the transportation industry.