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Technical Paper

A Methodology for Accelerated Thermo-Mechanical Fatigue Life Evaluation of Advanced Composites

2024-06-01
2024-26-0421
Thermo-mechanical fatigue and natural aging due to environmental conditions are difficult to simulate in an actual test with the advanced fiber-reinforced composites, where their fatigue and aging behavior is little understood. Predictive modeling of these processes is challenging. Thermal cyclic tests take a prohibitively long time, although the strain rate effect can be scaled well for accelerating the mechanical stress cycles. Glass fabric composites have important applications in aircraft and spacecraft structures including microwave transparent structures, impact-resistant parts of wing, fuselage deck and many other load bearing structures. Often additional additively manufactured features and coating on glass fabric composites are employed for thermal and anti-corrosion insulations. In this paper we employ a thermo-mechanical fatigue model based accelerated fatigue test and life prediction under hot to cold cycles.
Technical Paper

FE Modelling and Experimental Evaluation for the Surface Integrity of Thin Walled Aluminum Alloy

2024-06-01
2024-26-0429
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.
Technical Paper

Effect of Fatigue Loads on Behavior of 2024-T351 Aluminum Conduits for Aircraft Hydraulic Applications

2024-06-01
2024-26-0431
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.
Technical Paper

A Multi-Scale Computational Scheme for Prediction of High-Cycle Fatigue Damage in Metal Alloy Components

2024-06-01
2024-26-0430
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.
Standard

Primer, Anodic Electrodeposition for Aircraft Applications

2024-05-01
WIP
AMS3144B
This specification establishes the requirements for a waterborne, corrosion inhibiting, chemical and solvent resistant, anodic electrodeposition epoxy primer capable of curing at 200 to 210 °F (93 to 99 °C).
Standard

Coating System, Advanced Performance, for Exterior Aerospace Applications

2024-04-30
WIP
G824AA
This specification establishes the requirements for coating systems having high durability for use as aircraft exterior surface finishes. These coating systems normally are comprised of a surface treatment, a primer, and a topcoat and include a chemical stripper and a cleaning compound for topcoat washing.
Standard

Aluminum Alloy, Extruded Profiles (2395-T84), 3.95Cu - 1.15Li - 0.3Ag - 0.5Mg - 0.1Zr, Solution Heat Treated, Stress Relieved by Stretching, and Aged

2024-04-25
CURRENT
AMS4359A
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).
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