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 novel method for Single Event Effect (SEE) Radiation Testing using Built-In Self-Test (BIST) feature of indigenously developed Vikram1601 processor is discussed. The novelty is that the usage of BIST avoids need of exhaustive test vectors to ensure test coverage of all the internal registers and physical memory to store them. So processor is the only element vulnerable to radiation damage during testing. The test design was carried out at VSSC, Trivandrum and the testing was carried out at IUAC, Delhi. In the first part, a brief introduction, need and methods of radiation testing of electronics especially SEE of radiation on Silicon based devices, different radiation effects, radiation damage mechanisms and testing methods are described. A brief introduction to Vikram1601 processor, the instruction – TST, used as BIST and testing scheme implementation using TST for studying the SEE is explained.
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 procurement specification covers aircraft quality self-locking nuts for wrenching (hex, spline) and anchor (plate, gang channel, shank) types of nuts made from a corrosion and heat-resistant nickel-base alloy of the type identified under the Unified Numbering System as UNS N07001. Tension height nuts having overall length of threaded portion not less than 1.2 times the nominal thread diameter have 1210 MPa minimum tensile strength at room temperature. Shear height nuts having shorter threaded portion have 1100 MPa minimum tensile strength at room temperature. Maximum test temperature of parts is 730 °C.
This document covers the recommended practice for determining the acceptability of the dendrite arm spacing (DAS) of D357-T6 aluminum alloy castings required to have tensile strength not lower than 50 ksi (345 MPa).
This document covers all metal, self-locking wrenching nuts, plate nuts, shank nuts, and gang channel nuts made from a corrosion and heat resistant steel of the type identified under the Unified Numbering System as UNS S66286 and of 160 ksi tensile strength at room temperature, with maximum test temperature of parts at 1200 °F.
This specification covers a precipitation hardenable, corrosion- and heat-resistant nickel alloy in the form of seamless tubing 0.125 inch (3.18 mm) and over in nominal OD and 0.015 inch (0.38 mm) and over in nominal wall thickness.
This specification covers a magnesium alloy in the form of sheet and plate from 0.016 to 3.000 inches (0.41 to 76.20 mm), inclusive, in thickness (see 8.5).
This specification covers a magnesium alloy in the form of extruded bars, rods, wire, tubing, and profiles up to 40 square inches (258 cm2) in cross-sectional area (solids) and up to 8.5 inches (216 mm) OD by 1.188 inches (30.18 mm) wall thickness (tubing) (see 8.5).
This document covers flexible and semiflexible, reinforced and unreinforced air hoses fabricated from laminated and impregnated fabric, intended for use in aircraft heating, air conditioning, ventilating, defrosting, and/or deicing systems.
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).