Shear resistance of sandwich panel connection at elevated temperature

PurposeSandwich construction has developed and has become an integral part of lightweight construction. In the recent projects, it has been shown that by using sandwich panels as stabilizing members, a considerable amount of savings of steel can be achieved for structural members at ambient temperature. These stabilizing effects may also help to achieve similar savings in case of fire.Design/methodology/approachThe response of a sandwich single panel as well as the behaviour of the whole structure at ambient temperature and in case of fire is influenced by joints between the sandwich panels and the sub-structure. The fastenings used to fix the sandwich panels to a sub-structure may be loaded by shear forces caused by self-weight, live loads or diaphragm action. Therefore, an experimental investigation was conducted to investigate the shear behaviour of sandwich panel joints in fire.FindingsThis paper summarized briefly the experimental results, numerical simulations and analytical models on the shear behaviour of sandwich panel joints at ambient and elevated temperatures.Research limitations/implicationsThe work is limited to studied types of screws and sandwich panels which are generally used in current sandwich construction.Practical implicationsThese stabilizing effects in sandwich construction help to achieve savings in case of fire.Social implicationsSandwich construction has developed and has become an integral part of lightweight construction. In the recent projects, it has been shown that by using sandwich panels as stabilizing members, a considerable amount of savings of steel can be achieved for structural members at ambient temperature. These stabilizing effects help to achieve similar savings in case of fire.Originality/valueThis paper summarized briefly the experimental results, numerical simulations and analytical models on the shear behaviour of sandwich panel joints at ambient and elevated temperatures, which were not published yet.

Optimal design of sandwich floor panels made of high-strength composite materials considering stiffness constraints

The article considers the challenge of designing sandwich floor panels made of high-strength composites considering stiffness constraints. A dimensionless criterion is proposed for assessing the stiffness of floor panels. A new constraint equation determines an interrelation between geometrical parameters of composite constructions and a given criterion. A demo example and the results of designing a typical floor panel using a high-strength composite material are presented. The mass of a square meter of the structure is considered as an objective function, and the thickness of the skin and the height of the honeycomb core of a sandwich construction are considered as design variables. In order to find the optimal ratio of design variables, a graphical interpretation of the design problem is used considering strength and stiffness constraints in the design space. It is noted that the presence of restrictions on a given value of the permissible relative deflection leads to an increase in the required height of the honeycomb filler with an insignificant consumption of additional mass of the sandwich construction.

Manufacturing process, mechanical behavior and modeling of composites structures sandwich panel

The complexity of sandwich structures is a challenge for aeronautics designers. Sandwich construction is widely used in both the aerospace and commercial industries because it is an extremely lightweight structural approach with high rigidity and strength/weight ratios. Although today's technology offers the possibility to combine a variety of materials for these structure solutions, in aviation only a few materials are accepted. This paper presents the technological process of making these sandwich structures, as well as a study of the characterization and testing of a sandwich structure to analyze the behavior from a mechanical point of view. The conclusions of the paper represent an experimental basis on which further research will be built.

Milling of an Al/CFRP Sandwich Construction with Non-Coated and TiAlN-Coated Tools

In this study, the effect of cutting parameters on the quality of an Al/CFRP sandwich structure (aluminium alloy–carbon fibre reinforced polymer) after milling with uncoated and TiAlN-coated tools was examined. The results of the cutting force were also investigated. The research was conducted in a VMC 800 HS vertical machining centre with a variable cutting speed and feed. The milling process was carried out using a non-coated, two-blade carbide milling cutter with a 35° helix angle and an analogous tool with a TiAlN coating. The surface quality was characterised in terms of the height deviation, which is one of the shape deviations after machining hybrid materials. The research showed that the maximum (77.60 µm) and minimum (1.78 µm) values of the height deviations were obtained using the tool with a TiAlN coating. It was found that the tested factors had significant effects on the height deviation, where the feed had the greatest influence and the cutting speed had the lowest influence on the surface quality. The tested factors were not statistically significant in terms of the cutting force.