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.

Optimization of honeycomb sandwich floor panels made of polymer-matrix low-combustible composite materials based on high-strength carbon and glass fibers and adhesive binder

The article deals with the task of designing aircraft honeycomb sandwich floor panels considering experimental data on the mechanical properties of new high-strength low-combustible composite materials. The developed experimental and analytical design procedure and optimization algorithm are described. The design task is formulated in terms of nonlinear mathematical programming in which the mass per square meter of the construction is the objective function. The thickness of the base layers, the height of honeycomb core and some other parameters are considered as the design variables. The proposed visual interpretation of the optimal design task allows reducing possible design solutions based on the experimental data to an enumeration of a limited number of design alternates. The article presents a demo task and the results of designing floor panes for an advanced passenger aircraft in the aisle area using a new low-combustible composite material. The floor panel is regarded as a continuous multiply supported plate loaded with distributed load. The proposed grapho-analytical method makes it possible to form the area of rational designs that differ from the optimal one in terms of mass by a specified allowable value. The performed computational and experimental analysis shows that with the use of the new material, a floor panel can be designed with base layers made of carbon or fiberglass and lightweight honeycomb filler with the mass of a square meter from 2,9 to 3,4 kg, which is the state-of-the-art.

Development of Ecofriendly Snail Shell Particulate-Reinforced Recycled Waste Plastic Composites for Automobile Application

The increase in demand for thermoplastics as a light-weight material for automobile application and other commercial purposes prompts more research into the available polymer resources. In this research, the possibility of enhancing the performance of recycled waste plastics (RWP) as polymer-based composites was examined. Particulate snail shell was obtained by grounding and sieving snail shells to obtain 53–63 μm passing which was used as reinforcement in the recycled waste plastics. The composites were developed by adding varying proportions of the snail shell particulate (SSP) to RWP using a randomly dispersed process in a hot compression moulding machine maintained at 190°C for 7 min. Selected properties of SSP-reinforced RWP composites were examined. The results showed an appreciable enhancement in the properties of composites developed compared to an unreinforced RWP matrix that serves as control. The ultimate tensile strength was enhanced by about 64%, while Young’s Modulus and impact strength were enhanced by 37% and 29%, respectively. Wear and water repellant potentials were highly enhanced with the addition of 15 wt% of SSP with values of about 52% and 91%, respectively. This revealed that high content of the SSP contributes to the improvement of the strain-hardening potentials of the developed composites. The results showed that this composite material can be suitably adapted for use in the interior of automobiles as door sills or the floor panel.

Methodology for multiscale design and optimization of lattice core sandwich structures for lightweight hopper railcars

This research is focused on developing new lightweight structures for railcars based on a pre-selected material, i.e. Al 2099. The goal is to design a new sandwich structure with an octet truss lattice core for a floor panel of a hopper freight railcar designed to meet North American standards. For that, mesoscale to macroscale design of the sandwich panel was performed. In mesoscale design, relative density, elastic properties, strength properties, and failure criterion of the lattice unit cell were investigated. In the next step, these properties were used as inputs for macroscale design, i.e. design of the whole sandwich structure. Multiple failure modes associated with the lateral loading of a sandwich panel were analyzed. These equations in conjunction with the minimum weight target led to an optimization problem, and the minimum required thicknesses were obtained. Finally, the new optimized design was validated by comparing different finite element simulations with the exact analytical equations. By using this type of structure, a 53% weight reduction was achieved on the floor panel which ultimately led to an estimated 12.5% reduction in the weight of the whole freight railcar body.

The smoke emission properties of selected elements of furnishing apartments in the building

The paper presents the results of tests for smoke optical density conducted on four various floor panels of building interior design. As regards safety, wood base or polymeric panels are flammable materials, and their ignitability and smoke generation depend to a large extent on its chemical composition, density and thickness of element. Smoke emission is one of basic elements that characterise the fire environment. Consequently the objective of the paper was to carry out a comparative analysis of smoke generation of chosen floor panels at selected thermal expositions and at the presence or absence of a stimulus igniting the volatile gaseous phase (pilot flame). For needs of experimental research use was made of: samples (oak board), wood-based materials (two type of HDF panels) and PVC floor panel. Experimental research has been carried out based on the standard PN ISO 5659 – 2:2013-06. The tests results were compared with international optical smoke density requirements for the interior design of ships and trains.