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The benefits of using Composite Bearings in Aircraft Shock Absorbers

Trelleborg Sealing Solutions-Brian Bowen, Torben A. Andersen
  • Technical Paper
  • 2019-01-1898
To be published on 2019-09-16 by SAE International in United States
This paper will use actual examples from aircraft recently introduced into service, to describe the main advantages of changing from the currently used metallic bearings, to composite bearings. Abstract: The introduction of composite bearing in a recently introduced twin aisle aircraft has resulted in: • Weight saving, by replacing bronze bearings with plastic bearings • Lowering of the particle count in the shock absorber oil, (Reduced contamination with metal particles) leading to reduced wear on seals and bearings. Qualification testing showed that Composite Bearings are able to provide longer service life than bronze bearings.
 

Forces vibration assistance for TA6V/CFRP drilling

ENSAM Paris-CHERIF MEHDI
  • Technical Paper
  • 2019-01-1874
To be published on 2019-09-16 by SAE International in United States
For aircraft structures, mechanical assembly using fasteners remains the most common technology. The setting of the numerous fasteners requires a large number of drilling operations. In the case of CFRP/TA6V stacks, the drilling still remains a technological challenge. Indeed the high-quality requirements by the aeronautic standards are limited by the fast damaging drilling tool phenomena. For TA6V, the forced assisted drilling provides a breakthrough technology. An axial forced oscillating displacement on the feed direction of the tool allows the creation of segmented chips. Those small chips are then easily evacuated from the cutting area using a vacuum device. This allows the improvement of the hole’s roughness and mastering the burr creation at the exit of the hole. The lubrication process is also enhanced during the exit sequence of the tool. For the CFRP/TA6V configuration, the segmented geometry of the chip avoids the roughness degradation on the composite part of the stack. This parameter can modify the cyclic bearing performance of the assembly. In this paper, the different forced drilling industrial solutions are analyzed. More specifically,…
 
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Bearing, Roller, Self-Aligning Single Row Anti-Friction, Sealed -65 to 350 °F, Type I

ACBG Rolling Element Bearing Committee
  • Aerospace Standard
  • AS21431C
  • Current
Published 2019-06-06 by SAE International in United States

Scope is unavailable.

 
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Bearing, Roller, Needle, Single Row, Thin Shell, Type II, Antifriction, Inch

ACBG Rolling Element Bearing Committee
  • Aerospace Standard
  • AS24462B
  • Current
Published 2019-06-06 by SAE International in United States

Scope is unavailable.

 
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Bearing, Roller, Needle, Double Row, Heavy Duty, Track Roller, Sealed, Type VI, Inch

ACBG Rolling Element Bearing Committee
  • Aerospace Standard
  • AS21439D
  • Current
Published 2019-06-06 by SAE International in United States

Scope is unavailable.

 
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Rolling Element Bearing Axial and Radial Internal Clearance

ACBG Rolling Element Bearing Committee
  • Aerospace Standard
  • ARP5483/3B
  • Current
Published 2019-06-06 by SAE International in United States

This test method outlines the standard procedure for measuring the radial and axial internal clearance of rolling element bearings used in airframe controls.

 
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Role of Dynamic Stiffness in Effective Isolation

Deere & Company-Yuzhen Yang
John Deere India Pvt, Ltd.-Balavardhan Reddy Dasabai
Published 2019-06-05 by SAE International in United States
In any machinery, avoiding noise and vibration completely is a difficult task due to the structural dynamic behaviors of components. To safeguard the operator, it is important to best isolate the operator station from NVH environment. Cabin isolation is an important aspect to minimize structure borne noise and tactile vibrations to be transferred into the cabin. Isolators are selected based on the isolation system inertial properties at mounting locations in the operating frequency range interested. The most important assumption to select isolators are that the active side and passive side of the isolators are nearly rigid so impedance mismatch is created for effective isolation.This paper describes the importance of dynamic stiffness of the structures on both the active and passive side for better NVH performance. NVH performance of passive side is evaluated analytically and computationally in terms of tactile vibrations and structure borne noise for various ratios of the dynamic stiffness over isolator stiffness. The isolator selection criterion is also discussed based on rigid body modes, operating frequency range, transmissibility ratio, and kinematic energy distributions.
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Fault Feature Extraction of Elliptically Shaped Bearing Raceway

South China University of Technology-Yingying Guo, Xuezhi Zhao
Published 2019-06-05 by SAE International in United States
The elliptically shaped bearing (ESB) with a rigid, elliptical inner race and a flexible, thin-walled outer race is the most easily damaged core component of harmonic drive. The ESB rotates under cycle load of alternating stress due to its special elliptic structure. Hence, the fault features of ESB such as fatigue spalling and pitting are apt to be concealed by the excitation of impulses caused by alternating between major axis and minor axis. In order to diagnose the fault on raceway surfaces of ESB, a new method of CMWT-FH based on Continuous Morlet Wavelet Transform (CMWT) and FFT-based Hilbert (FH) spectrum analysis is proposed to extract the fault feature. First, the formulas of feature frequency is deduced based on the geometry and kinematics characteristics of ESB; then the CMWT method is employed to decompose the fault signal of ESB; finally, the FH spectrum analysis is performed to extract the feature frequency of faulty ESB from the decomposition signal with the maximum kurtosis in the first several layers. Compared with the traditional FH method, the feature…
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Structure-Borne Prediction on a Tire-Suspension Assembly Using Experimental Invariant Spindle Forces

Siemens Industry Software NV-Jesús Ortega Almirón, Fabio Bianciardi, Patrick Corbeels
Published 2019-06-05 by SAE International in United States
Road induced noise is getting more and more significant in context of the electrification of the powertrain. The automotive industry is seeking for technologies to predict the contribution of vehicle components upfront, early in the development process. Classical Transfer Path Analysis (TPA) is a well-established technique that successfully identifies the transmission paths of noise and vibration from different excitation sources to the target responses. But it has a drawback: it requires the physical availability of the full vehicle. To achieve shorter development cycles, to avoid costly time-consuming design iterations and due to the limited availability of prototypes, engineers derived a method that addresses these requirements. Component-based TPA is a relatively new structure borne substructuring approach that allows to characterize the source excitation by a set of equivalent loads (blocked forces) independently from the receiver structure and to predict its behavior when coupled to different receivers. Frequency Based Substructuring, FBS, is applied in order to obtain the coupled assembly. However, there are a number of challenges affecting its applicability, such as the proper modelling of the…
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Experimental Investigation on Gear Rattle Noise Reduction in Passenger Car

Maruti Suzuki India Limited-Devendra Kumar Khare, Abhishek Lakhanlal Vaishya, Archan Sunibhai Pujara, Radhe Krishna, Kingshuk Satpathy, Ved Prakash Choudhary, Anant Pandey
Published 2019-06-05 by SAE International in United States
Gear rattle noise reduction inside the passenger cabin is one of the major challenges for customer comfort enhancement. Therefore, it becomes a prime target during transmission design and development. Gear rattle is generated due to meshing teeth collision of free gears, which is caused due to torsional vibration of engine transferred through clutch. Vibrations are generated due to free gears teeth impact and are transferred to shaft, bearings and transmission housing. The sound absorption and structural vibration of transmission housing was optimized by changing the geometrical features of the transmission housing that affects radiated noise.Experimental approach for gear rattle noise reduction through transmission housing modification is described in this paper. Moreover, CAE method is also incorporated with the experiments for optimization of future vehicle transmission system designs.
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