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Hypersonic flight vehicles have potential applications in strategic defence, space missions, and future civilian high-speed transportation systems. However, structural integration has significant challenges due to extreme aero-thermo-mechanical coupled effects. Scramjet-powered air-breathing hypersonic vehicles experience extreme heat loads induced by combustion, shock waves and viscous heat dissipation. An active cooling thermal protection system for scramjet applications has the highest potential for thermal load management, especially for long-duration flights, considering the weight penalty associated with the heavier passive thermal insulation structures. We consider the case of active cooling of scramjet engine structural walls with endothermic hydrocarbon fuel. We have developed a semi-analytical quasi-2D heat transfer model considering a prismatic core single cooling channel segment as a representative volume element (RVE) to analyse larger-scale problems.

Abstract: The present study discusses about the effect of installation torque on the surface and subsurface deformations for thin walled 7075 aluminum alloy used in Aerospace applications. A FE model was constructed to predict the effect of torque induced stresses on thin walled geometry followed with an experimentation. A detailed surface analysis was performed on 7075 aluminum in terms of superficial discontinuities, residual stresses, and grain deformations. The localized strain hardening resulting from increased dislocation density and its effect on surface microhardness was further studied using EBSD and micro indentation. The predicted surface level plastic strain of .25% was further validated with grain deformations measured using optical and scanning electron microscopy.

A typical high-pressure hose assembly consists of hose made with synthetic polymer braids and Teflon tube crimped with metallic fittings. These hose assemblies are mainly used for aircraft landing gear application considering its high-pressure sustenance and better flexibility. The proposed study investigates the effect of thermo-mechanical stress generated due to cyclic soaking and flexibility testing at thermostatic subzero (-65°F) and high temperature (+275°F) on performance of high-pressure hose assembly. This effect is further studied through hose tear-down which was envisioned to investigate the hose layer degradation and focused on changes in inner PTFE tube, which ultimately leads to product performance issues. Keywords: braids, tear down analysis, thermo-mechanical, inter-layer abrasion.

Abstract: Hydraulic systems in aircrafts largely comprise of metallic components with high strength to weight ratios which comprise of 2024 Aluminum and Titanium Ti-6AL-4V. The selection of material is based on low and high pressure applications respectively. For aircraft fluid conveyance products, hydraulic conduits are fabricated by axisymmetric turning to support flow conditions. The hydraulic conduits further carries groves within for placement of elastomeric sealing components. This article presents a systematic study carried out on common loads experienced by fluid carrying conduits and the failure modes induced. The critical failure locations on fluid carrying conduits of 2024-T351 Aluminum was identified, and the Scanning Electron Microscope (SEM) analysis was carried out to identify the characteristic footprints of failure surfaces and crack initiation. Through this analysis, a load to failure mode correlation is established.

Aerospace structural components grapple with the pressing issue of high-cycle fatigue-induced micro-crack initiation, especially in high-performance alloys like Titanium and super alloys. These materials find critical use in aero-engine components, facing a challenging combination of thermo-mechanical loads and vibrations that lead to gradual dislocations and plastic strain accumulation around stress-concentrated areas. The consequential vibration or overload instances can trigger minor cracks from these plastic zones, often expanding unpredictably before detection during subsequent inspections, posing substantial risks. Effectively addressing this challenge demands the capability to anticipate the consequences of operational life and aging on these components. It necessitates assessing the likelihood of crack initiation due to observed in-flight vibration or overload events.

This specification covers an aluminum alloy in the form of alclad sheet over 0.039 to 0.126 inches (0.99 to 3.20 mm), inclusive, in nominal thickness with a fine-grain core of ASTM No. 6 or finer (see 8.5).

This specification covers an aluminum alloy in the form of extruded rods, bars, and profiles (shapes) 0.040 to 1.500 inches (1.02 to 38.10 mm), inclusive, in thickness, and produced with maximum cross-sectional area of 23.25 square inches (15000 mm2) and a maximum circumscribing circle diameter (circle size) of 15.5 inches (394 mm) (see 2.4.1 and 8.6).

This specification covers an aluminum alloy in the form of sheet and plate 0.017 to 2.000 inches (0.43 to 50.80 mm), inclusive, in nominal thickness (see 8.6).

This specification covers an aluminum alloy in the form of sheet 0.020 to 0.128 inch (0.51 to 3.25 mm), inclusive, in nominal thickness (see 8.5).

This specification covers an aluminum alloy in the form of plate 1.000 to 6.000 inches (25.40 to 152.40 mm), inclusive, in nominal thickness (see 8.5).

This specification covers an aluminum alloy in the form of alclad sheet and plate supplied in the -T861 temper.

This specification covers an aluminum alloy in the form of alclad coiled sheet from 0.010 to 0.128 inch (0.25 to 3.25 mm), inclusive, in thickness supplied in the -T4 temper (see 8.5).

This specification covers a titanium alloy in the form of welding wire (see 8.5).

This specification covers a titanium alloy in the form of bars up through 4.000 inches (101.60 mm) in nominal diameter or least distance between parallel sides, inclusive, forgings of thickness up through 4.000 inches (101.60 mm), inclusive, with bars and forgings having a maximum cross-sectional area of 32 square inches (204.46 cm2), and stock for forging of any size (see 8.6).

This procurement specification covers the requirements for metal tube support clamps comprising of two spring clips made of corrosion and heat resistant steel and the associated PTFE single split cushion that supports the tube. See Figure 1.

This procurement specification covers aircraft-quality solid rivets made from a corrosion resistant nickel-copper alloy of the type identified under the Unified Numbering System as UNS N04400 and of 46 ksi minimum shear strength.

This procurement specification covers tubular, blind rivets fabricated from a corrosion resistant nickel-copper alloy of the type identified under the Unified Numbering System as UNS N04405, and of 52 ksi minimum shear strength for self-plugging style rivets.

This procurement specification covers solid rivets and hollow end rivets made from a corrosion and heat resistant steel of the type identified under the Unified Numbering System as UNS S66286 and of 80 ksi single shear strength at room temperature.