[en] An efficient procedure to obtain the optimal stacking sequence and the minimum weight of stiffened laminated composite curved panels under several loading conditions and stiffener layouts has been developed based on the finite element method and the genetic algorithm that is powerful for the problem with integer variables. Often, designing composite laminates ends up with a stacking sequence optimization that may be formulated as an integer programming problem. This procedure is applied for a problem to find the stacking sequence having a maximum critical buckling load factor and the minimum weight. The object function in this case is the weight of a stiffened laminated composite shell. Three different types of stiffener layouts with different loading conditions are investigated to see how these parameters influence on the stacking sequence optimization of the panel and the stiffeners. It is noticed from the results that the optimal stacking sequence and lay-up angles vary depending on the types of loading and stiffener spacing

[en] Author considers the formulation and algorithms of the nonstationary problem for calculation of temperature fields of shell of revolution in high-temperature aerodynamic flow with known temperature. The physical model and calculation of temperature fields in the frontal part and in circle sections of the shell of revolution are also proposed

[en] Highlights: ► Ultimate strength at transient heating is critical to security design of missiles. ► We measure the ultimate strength of alloy 2017 subjected to transient heating. ► Experimental results at transient heating are lacking in strength design handbook. ► Ultimate strength of alloy 2017 experimented is much higher than handbook value. ► The results provide a new method for optimal design of high-speed flight vehicles. -- Abstract: Alloy 2017 (Al–Cu–Mg) is a hard aluminium alloy strengthened by heat treatment. Because of its higher strength, finer weldability and ductility, hard aluminium alloy 2017 has been widely used in the field of aeronautics and astronautics. However, the ultimate strength and other characteristic mechanical parameters of aluminium alloy 2017 in a transient heating environment are still unclear, as these key mechanical parameters are lacking in the existing strength design handbook. The experimental characterisation of these critical parameters of aluminium alloy 2017 is undoubtedly meaningful for reliably estimating life span of and improving safety in designing high-speed flight vehicles. In this paper, the high-temperature ultimate strength, loading time and other mechanical properties of hard aluminium alloy 2017 under different transient heating temperatures and loading conditions are investigated by combining a transient aerodynamic heating simulation system and a material testing machine. The experimental results reveal that the ultimate strength and loading capability of aluminium alloy 2017 subjected to transient thermal heating are much higher than those tested in a long-time stable high-temperature environment. The research of this work not only provides a substantial basis for the loading capability improvement and optimal design of aerospace materials and structures subject to transient heating but also presents a new research direction with a practical application value.

[en] The requirements on the use of titanium alloys used as thermal protection in hypersonic airplanes are considered. The ignition of titanium alloys in aerodynamic heating is analyzed. A mathematical model is proposed for the surface oxidation of the alloys in a high-temperature air flux.

[en] Highlights: • A TMS consisting of passive TPS and ACN is developed for a hypersonic launch vehicle. • The coupled design method of TPS and ACN is developed based on an equivalent thermal equilibrium model. • An equivalent HTC is proposed to indicate the overall capacity of ACN. -- Abstract: In this paper, a design method of thermal management system (TMS) for hypersonic vehicles is developed. The system consists of a passive thermal protection system (TPS) and an active cooling network (ACN) with coolant of kerosene. In most previous studies, the passive TPS and ACN are always designed separately and thus leads to over-conservative results that deviating from real engineering conditions. A coupled design method is developed in present work, and the process includes calculation of aerodynamic heat, determination of passive TPS concept distribution, computation of TPS and ACN scales, and iterative design. The coupled design is realized based on two keys, the active cooling is coupled in aerodynamic heating and heat transfer in TPS by an equivalent thermal equilibrium model, and the overall capacity of active cooling is indicated by an equivalent heat transfer coefficient. The model and the coefficient act as the rationale and the equivalent parameter of the whole process, respectively. The TMS of a reusable launch vehicle is established under a typical trajectory. The influences of equivalent heat transfer coefficient on aerodynamic heating, passive TPS and ACN are studied. The results show that the weight of passive TPS decreases, while the coolant mass flow rate increases with the enhancement of active cooling.

[en] Attempt was made to explain the reduced efficiency of zirconium coatings with increasing the rate of free stream from the standpoint of physics of interaction of atoms with solid surface. Comparison of kinetic energy of nitrogen hypersonic flow with the energy, when collective interaction of these atoms with zirconium replaces by individual one, demonstrated that change in the mechanism of interaction could cause increased aerodynamic heating of materials with zirconium coatings

[en] RTG(Radioisotope Thermoelectric Generator) is a power generation system using the decay heat of radioisotope, it's the power without being charged from outside, it's utilized for special purposes of space exploration and deep sea exploration. For instance, a RTG called as SNAP-3 utilized in Transit 4A for space exploration. These days, the Korea Atomic Energy Research Institute is developing an RTG for aerospace. RTGs for space exploration is required that the structural integrity verification for aerodynamic heating in case of an accident. In this study, diverse designs of HSM were considered. The optimal thickness of insulation material inside HSM(Heat source module) is predicted for the structural integrity of HSM using heat transfer analysis. The safety criterion is that the maximum temperature of iridium clad do not exceed 1400.deg.C by aerodynamic heating during 300s. In this study, a heat transfer analysis was conducted to find optimal thickness of GIS and sleeve to avoid melting of iridium clad for HSM-1 and HSM-2.

[en] A conjugated problem statement for aerodynamics and thermomechanics of heat-shielding structures from thermally decomposing polymer composite materials is proposed. It is based on the iterative solution of the three types of detached problems: aerogasdynamics problem for viscous heat-conducting flows, internal heat and mass transfer and thermoelasticity of shell constructions. An example of the numerical solution of the conjugated problem is given. It is shown that due to the high temperatures of the aerodynamic heating of the structure made of a polymer composite material there can appear a polymer phase thermodecomposition and intensive internal gas generation into the structure of the material. (paper)

[en] Highlights: • A combined thermal control approach for preventing serious aerodynamic heating is proposed. • The thermal control effect of the proposed method is simulated and analyzed. • The engineering practicability is evaluated by a mass penalty method. A 5 mm-wide gap of a shaft connected to the rudder in a hypersonic vehicle is exposed without any heat insulation bearing serious aerodynamic heating. A new thermal control approach combining CO₂ flow forced convection in the central inner channel with copper-plating on the outer surface is proposed to prevent the temperature of the gap from exceeding the material’s highest tolerance temperature. Based on the integrated thermal management, CO₂ first cools the electronic equipment after being gasified from a high-pressure cylinder, and then moves into the shaft for active thermal control. The thermal control performance is simulated, and the results show the proposed method could satisfy with the thermal control requirements, however, the thermal control requirements could not be fulfilled if the forced CO₂ flow convection or the copper-plating was used alone. The mass penalty was estimated within a weight of 11 kg which is quite feasible for engineering applications.

[en] Interaction behaviors of high-speed compressible viscous flow and thermal-structural response of structure are presented. The compressible viscous laminar flow behavior based on the Navier-Stokes equations is predicted by using an adaptive cell-centered finite-element method. The energy equation and the quasi-static structural equations for aerodynamically heated structures are solved by applying the Galerkin finite-element method. The finite-element formulation and computational procedure are described. The performance of the combined method is evaluated by solving Mach 4 flow past a flat plate and comparing with the solution from the finite different method. To demonstrate their interaction, the high-speed flow, structural heat transfer, and deformation phenomena are studied by applying the present method to Mach 10 flow past a flat plate