Influence of Applied Misalignment on the Balanced High Speed Flexible Coupling of Fighter Aircraft

2014 ◽  
Vol 592-594 ◽  
pp. 1084-1088 ◽  
Author(s):  
S. Nagesh ◽  
A.M. Junaid Basha ◽  
G. Thakur Dinesh Singh
Keyword(s):  
High Speed ◽  
Aircraft Engine ◽  
Light Weight ◽  
Fighter Aircraft ◽  
Flexible Coupling ◽  
Flexible Plates ◽  
Exciting Forces ◽  
Reaction Forces ◽  
Differential Thermal Expansion ◽  
Gear Box

The fighter aircraft transmission system consists of a light weight, High Speed Flexible Coupling (HSFC), used to transmit power from engine gear box to accessory gear box at speed ranging from 10,000 to 18,000 rpm. The HSFC accommodates larger parallel and axial misalignment resulting from differential thermal expansion of the aircraft engine and mounting arrangement. As the HSFC operates at higher rotational speeds close to critical velocities, it is important to analyze, the unbalance exciting forces considering the misalignment. In the present work, prediction of critical speed by camp bell diagram and unbalance response of the HSFC has been carried out using FEA. An experimental investigation also been carried out to study the influence of applied misalignment on a bi-plane dynamically balanced HSFC. The study shows that lower reaction forces are transmitted to HSFC end supports with the applied misalignments, as they are accommodated by the elastic material flexure of flexible plates.

Integrated Simulation and Structure Optimization of Rigid-Flexible Coupling Mechanical Leg Based on PATRAN, NASTRAN and ADAMS

2014 ◽  
Vol 614 ◽  
pp. 16-18 ◽  
Author(s):  
Wen Tao Zhao ◽  
Yong Zheng Li ◽  
Sen Wang
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Structure Optimization ◽  
High Load ◽  
Stress And Strain ◽  
Intermediate Structure ◽  
Light Weight ◽  
Flexible Coupling ◽  
Integrated Simulation ◽  
High Load Capacity

According to the requirements of light weight, low-energy and short development period under the conditions that leg mobile robots exert high movement adaptability, high speed and high load capacity, integrated simulation and structure optimization of rigid-flexible coupling mechanical leg are proposed based on PATRAN, NASTRAN and ADAMS. Firstly, .bdf file is obtained via PATRAN. Secondly, MNF is acquired via NASTRAN. Thirdly, the rigid-flexible coupling mechanical leg is established, the motion of mechanical leg based on the trajectory planning is implemented, and integrated simulation is completed via ADAMS. Finally, Structure optimization is processed step-by-step and completed whenever intermediate structure meets the stress and strain requirements. The example is presented that illustrates advantages of the proposed method.

scholarly journals A High-Speed, Light-Weight Scalar Magnetometer Bird for km Scale UAV Magnetic Surveying: On Sensor Choice, Bird Design, and Quality of Output Data

2021 ◽  
Vol 13 (4) ◽  
pp. 649
Author(s):  
Arne Døssing ◽  
Eduardo Lima Simoes da Silva ◽  
Guillaume Martelet ◽  
Thorkild Maack Rasmussen ◽  
Eric Gloaguen ◽  
...  
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Regional Scale ◽  
Weather Conditions ◽  
Light Weight ◽  
Output Data ◽  
Efficient Manner ◽  
Flexible System ◽  
Scalar Data

Magnetic surveying is a widely used and cost-efficient remote sensing method for the detection of subsurface structures at all scales. Traditionally, magnetic surveying has been conducted as ground or airborne surveys, which are cheap and provide large-scale consistent data coverage, respectively. However, ground surveys are often incomplete and slow, whereas airborne surveys suffer from being inflexible, expensive and characterized by a reduced signal-to-noise ratio, due to increased sensor-to-source distance. With the rise of reliable and affordable survey-grade Unmanned Aerial Vehicles (UAVs), and the developments of light-weight magnetometers, the shortcomings of traditional magnetic surveying systems may be bypassed by a carefully designed UAV-borne magnetometer system. Here, we present a study on the development and testing of a light-weight scalar field UAV-integrated magnetometer bird system (the CMAGTRES-S100). The idea behind the CMAGTRES-S100 is the need for a high-speed and flexible system that is easily transported in the field without a car, deployable in most terrain and weather conditions, and provides high-quality scalar data in an operationally efficient manner and at ranges comparable to sub-regional scale helicopter-borne magnetic surveys. We discuss various steps in the development, including (i) choice of sensor based on sensor specifications and sensor stability tests, (ii) design considerations of the bird, (iii) operational efficiency and flexibility and (iv) output data quality. The current CMAGTRES-S100 system weighs ∼5.9 kg (including the UAV) and has an optimal surveying speed of 50 km/h. The system was tested along a complex coastal setting in Brittany, France, targeting mafic dykes and fault contacts with magnetite infill and magnetite nuggets (skarns). A 2.0 × 0.3 km area was mapped with a 10 m line-spacing by four sub-surveys (due to regulatory restrictions). The sub-surveys were completed in 3.5 h, including >2 h for remobilisation and the safety clearance of the area. A noise-level of ±0.02 nT was obtained and several of the key geological structures were mapped by the system.

scholarly journals Vibration Analysis of Rotor - Coupling - Bearing System With Misaligned Shafts

1996 ◽  
Author(s):  
A. Sreenivasa Rao ◽  
A. S. Sekhar
Keyword(s):  
Theoretical Model ◽  
Finite Elements ◽  
Vibration Analysis ◽  
Rotating Machinery ◽  
Value Analysis ◽  
Flexible Coupling ◽  
Eigen Value ◽  
Shaft Misalignment ◽  
Reaction Forces ◽  
Bearing System

The shaft misalignment, even being a common fault in rotating machinery, is not sufficiently studied. The present work addresses effects of misalignment in rotating machinery. An attempt to give a theoretical model for a rotor-coupling-bearing system has been done. The rotor-bearing system including the flexible coupling is modelled using the finite elements. The reaction forces and moments developed due to flexible coupling misalignment both for parallel and angular are derived and introduced in the model. Vibration analyses such as eigen value analysis and unbalance response are carried out for the rotor system with misaligned shafts.

Oil Pumping in High Speed and High Loaded Ball Bearings

2004 ◽  
Author(s):  
Michael Flouros
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Research Programme ◽  
Aircraft Engine ◽  
Ball Bearings ◽  
European Research ◽  
Rolling Bearings ◽  
Engine Design ◽  
Oil Flow ◽  
Total Oil

Trends in aircraft engine design cause increased mechanical stress requirements for rolling bearings. Consequently high amounts of heat are rejected which results in high oil scavenge temperatures. The direction of oil flow in the bearing can considerably affect the heat transported by the oil. An RB199 turbofan bearing and its associated chamber were modified to carry out the survey. The test bearing was a 124mm PCD ball bearing. The bearing has a split inner-ring employing under-race lubrication by two individual jets. The total oil flow could be devided to any ratio through the jets. This had an impact on the oil scavenge temperatures and the scavenge flows on both sides of the bearing. Significant reduction in the ‘heat to oil’ was achieved when oil was fed at certain proportions (ratio). This work is part of the European Research programme Brite Euram ATOS (Advanced Transmission and Oil Systems).

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