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.
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.
RAMBHA-LP (Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere - Langmuir Probe) is one of the key scientific payloads onboard the Indian Space Research Organization’s (ISRO) Chandrayaan-3 mission. Its objectives were to estimate the plasma density and its variations on the near lunar surface. The probe was initially kept in a stowed condition attached to the lander. A mechanism was designed and realized to meet the functional requirement of deploying the probe at a distance of 1 meter, equivalent to the Debye length of the probe in the moon’s plasma environment. The probe deployment mechanism consists of the Titanium alloy spherical probe with a Titanium Nitride coating on its surface to achieve a constant work function, a long carbon-fiber-reinforced polymer boom, a double torsion spring, a dust-protection box, and a shape-memory alloy-based Frangibolt actuator for low-shock separation. The entire mechanism weighed less than 1.5 kilograms.
This four-hour short course provides key considerations for the comparison of electrically supplied (Power-by-Wire, or PbW) and hydraulically supplied (Power-by-Pipe, of PbP) actuation for aerospace. The focus is put on the consequence, for designers, of changing the physical principles and the technology used. A particular attention is paid to the unavoidable side effects introduced by the technological realization. Simple examples with realistic numerical values are used to make the comparisons quantitatively realistic.
This four-hour short course intends to present an overview of electrically powered flight control actuation systems, covering commercial applications. The scope covers issues related to the mechanical design of actuators themselves, with limited reference to their control electronics. Additionally, this course will provide participants an understanding of the design considerations behind these actuation systems.
The test method describes the procedure for determination of the total acid number (TAN) of new and degraded polyol ester and diester-based gas turbine lubricants by the potentiometric titration technique. The method was validated to cover an acidity range of 0.05 to 6.0 mg KOH g-1. The method may also be suitable for the determination of acidities outside of this range and for other classes of lubricants.
This SAE Aerospace Standard (AS) describes the test methods to determine the flammability performance and capability to control the passage of, and effects from, fire on aircraft firewall sealing compounds. The methods are based on requirements of FAR Part 25, Sections 25.865, 25.867, 25.1191, and 25.1193 and may be used to demonstrate compliance with the requirements established by FAA AC 20-135. This standard shall be used in conjunction with applicable material specifications.
This SAE Aerospace Recommended Practice (ARP) provides the technical terms and nomenclature, together with their definitions and abbreviations/acronyms that are used in aerospace fluid power, actuation and control systems. NOTE: ARP490 and ARP4493 are sources for definitions specifically for electrohydraulic servovalves.
This specification covers an aluminum alloy in the form of sheet 0.063 to 0.236 inch (1.60 to 6.00 mm), incl, in thickness, clad on both sides (see 8.4).
As model-based systems engineering is proliferating throughout the aerospace industry as a method to manage the development of complex cyber-physical systems, opportunities to leverage formal methods for verification and validation purposes are significant. As a system model described in SysML can contain the level of semantics required to define strict system requirements, it is possible to create a translation tool to generate SRL (SADL (Semantic Application Design Language) Requirements Language) to leverage ASSERT™ (Analysis of Semantic Specifications and Efficient generation of requirements-based Tests) for verification and validation of the system requirements. SADL [13] is a controlled English grammar that translates directly into OWL (Web Ontology Language) [14]. As part of the validation of the SRL requirements, ASSERT™ leverages a theorem prover to look for conflict and completeness errors.
Abstract The ground vibration test (GVT) is an important phase in a new aircraft development program, or the structural modification of a certified aircraft, to experimentally determine the structural vibrational modes of the aircraft and their modal parameters. These modal parameters are used to validate and correlate the dynamic finite element model of the aircraft to predict potential structural instabilities (such as flutter), assessing the significance of modifications to research vehicles by comparing the modal data before and after the modification and helping to resolve in-flight anomalies. Due to the high cost and the extensive preparations of such tests, a new method of vibration testing called the taxi vibration test (TVT) rooted in operational modal analysis (OMA) was recently proposed and investigated as an alternative method to conventional GVT.
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.
This document defines the requirements for weld fittings and machine weldments using an orbiting welding head suitable for use on cold worked 3AL-2.5V titanium, 21Cr-6Ni-9Mn CRES, and 718 nickel alloy tubing. Fitting standards covered by this specification include non-separable welded elbow, tee, and reducer fittings, and reconnectable 24-degree cone fittings, such as sleeves and unions.