Optimal truss plates

Wicks, Nathan; Hutchinson, John W.

doi:10.1016/s0020-7683(00)00315-2

Cited by 339 publications

(201 citation statements)

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“…When configured as the cores of sandwich panels, cellular lattices can exhibit exceptional structural efficiency [77], [78]. The ________________________________________________________________________ mechanical properties of low relative density honeycomb (hexagonal, square, triangular types), truss (pyramidal, tetrahedral, Kagome types), and corrugated (triangular, diamond, NavTruss types) cores are well characterized, having been assessed in compression, shear, and bending, as well under conditions of high impulse loading [79], [80], [81], [82].…”

Section: Figure 211 Cross-section Schematic Of a Cylindrical Heat Pmentioning

confidence: 99%

Thermal Management at Hypersonic Leading Edges

Kasen

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The intense heat flux incident upon the leading edges of hypersonic vehicles traveling through the low earth atmosphere at speeds of Mach 5 and above requires creative thermal management strategies to prevent damage to leading edge components. Conventional thermal protection systems (TPSs) include the ablative coatings of NASA's Mercury, Gemini, and Apollo vehicles and the reusable reinforced carbon-carbon (RCC) system of the Space Shuttle Orbiter. The ablative approach absorbs heat by endothermic transformation (phase and/or chemical change to the polymeric coating). The heat is dissipated from the vehicle as the single-use coating eventually vaporizes. The RCC approach manages the intense heat by operating at high temperatures and radiating heat to its surroundings. The effectiveness of both approaches is predicated on keeping the heat flux that impinges upon the susceptible aluminum airframe below a critical level.ii ________________________________________________________________________ This dissertation has explored an alternative metallic TPS concept which seeks to redistribute the heat from the leading edge, thereby eliminating local hot spots. It makes use of high thermal conductance heat pipes coupled to the leading edge so that the thermal load may be redistributed from a high heat flux location (at the stagnation point) to regions where it can be effectively radiated from the vehicle. The sealed system concept is based upon the evaporation of a fluid near the heat source that sets up a region of elevated vapor pressure inside the pipe. The latent heat is transported down the resulting pressure gradient by the vapor stream where it condenses at cooler regions, releasing the heat for removal.Replenishment of the condensed working fluid to the evaporator region is accomplished through the capillary pumping action of a porous wick which lines the interior surface of the pipe.A design methodology for a wedge-shaped heat pipe is presented which uses a coupled flow-wall temperature model to construct design maps which relate design parameters of the leading edge system (overall length, wall thickness, and alloy) to its operating conditions (isothermal temperature, maximum temperature, maximum thermal stress). Potential bounds on heat transport due to physical phenomena linked to the sound speed within a chamber (sonic limit), capillarity, and boiling nucleation are considered by extending models developed for tube designs to the wedge geometry. A new heat flux limit is proposed which, should it be exceeded, subjects the leading edge to thermally-induced plastic deformation of the TPS. iii ________________________________________________________________________To investigate the validity of the design approach and thermal spreading effectiveness of the proposed concept, a low temperature wedge-shaped leading edge was designed and constructed using stainless steel as the case material and water as the working fluid. Under localized tip heating, the maximum temperatures were significantly reduced compa...

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Section: Figure 211 Cross-section Schematic Of a Cylindrical Heat Pmentioning

confidence: 99%

Thermal Management at Hypersonic Leading Edges

Kasen

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“…We consider a prismatic microtruss structure [6,24] shown in Figure 2; this example may be (interactively) accessed on our web site 2 . The truss consists of a frame (upper and lower faces, in dark gray) and a core (trusses and middle sheet, in light gray); the structure transmits a force per unit depthF uniformly distributed over the tip of the middle sheet,Γ 3 , through the truss system to the fixed left wall,Γ 0 .…”

Section: A Truss Structurementioning

confidence: 99%

A Mathematical and Computational Framework for Reliable Real-Time Solution of Parametrized Partial Differential Equations

Prud'Homme¹,

Rovas²,

Veroy³

et al. 2002

ESAIM: M2AN

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Abstract. We present in this article two components: these components can in fact serve various goals independently, though we consider them here as an ensemble. The first component is a technique for the rapid and reliable evaluation prediction of linear functional outputs of elliptic (and parabolic) partial differential equations with affine parameter dependence. The essential features are (i) (provably) rapidly convergent global reduced-basis approximations -Galerkin projection onto a space WN spanned by solutions of the governing partial differential equation at N selected points in parameter space; (ii) a posteriori error estimation -relaxations of the error-residual equation that provide inexpensive yet sharp and rigorous bounds for the error in the outputs of interest; and (iii) off-line/on-line computational procedures -methods which decouple the generation and projection stages of the approximation process. This component is ideally suited -considering the operation count of the online stage -for the repeated and rapid evaluation required in the context of parameter estimation, design, optimization, and real-time control. The second component is a framework for distributed simulations. This framework comprises a library providing the necessary abstractions/concepts for distributed simulations and a small set of tools -namely SimT E X and SimLaB-allowing an easy manipulation of those simulations. While the library is the backbone of the framework and is therefore general, the various interfaces answer specific needs. We shall describe both components and present how they interact.Mathematics Subject Classification. 65N15, 65N30, 68U01, 68U20, 68M14, 68M15.

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“…Brittain et al (2001) have analyzed mechanical properties of the micro plates with the truss core and proposed a new method for their manufacturing. Wicks and Hutchinson (2001) concluded that characteristics of the optimized sandwich plates with the truss core are superior to characteristics of plates with the honeycomb core or the stringerstiffened plates. Wicks and Hutchinson (2004) have further extended their analysis to sandwich plates with truss core subjected to fracture straining and combination of the bending moment and transversal force.…”

Section: Introductionmentioning

confidence: 99%

Behavior of the sandwich beam subjected to bending as a function of the core density

et al. 2016

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Abstract. The sandwich beam can be considered as the multi-layered structure with a symmetrical cross-section. In this paper is assumed that the structure is created by periodical repetition of a unit cell. The influence of its size on the beam's static behavior in bending was analyzed. The variation of the unit cells number affects the size of the cell, so the static analysis was performed -the flexural stiffness and the beam's deflection were determined as functions of the unit cells number. The two configurations of the sandwich beams were considered: the beam with the constant cross-section along its length and the beam with the periodically variable cross-section. The graphs of the beam's flexural stiffness and deflection variations in terms of the unit cells number were obtained. It was concluded that after a certain number of the cells, the core's density does not further influence the behavior of the sandwich beam, under the given loading conditions. The conclusion from comparison of the two configurations is that the sandwich beam with the variable cross-section behaves somewhat better than the beam with the constant cross-section. The FEM analysis has verified all the conclusions from the analytical solution about the sandwich beams behavior when subjected to bending.

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Optimal truss plates

Cited by 339 publications

References 1 publication

Thermal Management at Hypersonic Leading Edges

Thermal Management at Hypersonic Leading Edges

A Mathematical and Computational Framework for Reliable Real-Time Solution of Parametrized Partial Differential Equations

Behavior of the sandwich beam subjected to bending as a function of the core density

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