Thermal and Mechanical Characteristics of a Multifunctional Thermal Energy Storage Structure
Thermal energy storage (TES) sandwich-structures that combine the heat storage function with structural functionality are described. The structure consists of a thermal interface (TI) connected to a hollow plate lamination. Each laminate is a hollow aluminum plate having a series of mm-scale channels or compartments that are filled with phase change material (PCM). Heat storage is via the latent heat of the PCM. A generalized thermal response model that is applicable to a wide range of channel geometrical configurations is described. The model couples the thermal response of the TI to the hollow aluminum plate/PCM-volume. The temporal response of the system is easily obtained via numerical solution of two ordinary differential equations, which can be solved to give closed-form solutions subject to a simple assumption. Thermal analysis delineates geometrical configurations that have good thermal response characteristics. The mechanical properties of the laminated structure are determined experimentally. Four-point bending experiments are conducted using specimens made with three layers of hollow plates laminated using a structural adhesive. An energy method is developed to model both the deformation and strength of the laminated structure. The energy method is developed based on the assumption that plane cross sections of the structure remain plane under bending, a condition that is valid for both linear and nonlinear materials. The energy method can provide deformation of the aluminum laminates comparable with the experiments. Experiments and modeling indicate that these laminated structures have an excellent performance-to-weight ratio.
Flight deck heat spreader
Abstract Deployment of modern aircrafts such as MV-22 Osprey or F35B Joint Strike Fighter has caused buckling of aircraft carrier ship flight decks due to excessive heat impact from aircraft engine exhaust plumes during landing. This work describes a development of Flight Deck Heat Spreader (FDHS) that is placed over a flight deck landing spot to protect it from hot exhaust plumes. The FDHS consists of aluminum panels with supporting pillars, aluminum wick sintered directly to panels and supporting pillars, water with corrosion inhibitor working fluid, and is sealed by welding together individual panels. The FDHS operates similar to a vapor chamber i.e. water vapor spreads the heat. The FDHS has 60% of the weight of solid aluminum of the same size, it is rigid with good strength and mechanical impact loading resistance, and it can be scaled to large areas of more than 50 m2. This paper focuses on thermal modeling of the FDHS, fabrication and tests of 450 cm2 and 3721 cm2 FDHS prototypes, and selection of working fluid corrosion inhibitor. FDHS was demonstrated to effectively shield the flight deck during high temperature thermal exposure and that the FDHS cools 8-times faster than similar weight aluminum alloy plate.
Computation of the elastic properties of a resin impregnated wire mesh by the means of a homogenisation procedure.
The present paper presents a homogenisation technique applied to the problem of calculating equivalent material properties of a resin impregnated wire mesh. Although this type of material can be expected to possess, in general, a four-fold axis of rotational symmetry, it was found that a transversally isotropic model approximates the material behaviour to within 3.5%. It is therefore concluded that a transversally isotropic model is adequate for representing the resin impregnated mesh in structural calculations.