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INSA Toulouse-Alain Daidie
  • Technical Paper
  • 2019-01-1861
To be published on 2019-09-16 by SAE International in United States
Orbital drilling has proved to be advantageous to achieve aeronautical-level quality drilling (surface roughness, geometry control…) fully adapted for complex assemblies in a single operation. However, compared to conventional drilling method, this process leads to a drastic change in structure's fatigue life probably due to a non-optimised level of residual stress. The control of the mechanical behaviour of parts obtained by orbital drilling is the goal of the European-CleanSky collaborative R&D project RODEO (Robotized Orbital Drilling Equipment and Optimized Residual Stresses, GA no.738219). In this work, an orbital drilling unit (ORBIBOT) allowing high-speed-machining conditions was developed by PRECISE France, that can be integrated on a lightweight industrial robot. Cutting parameters were determined through an original Tool-Material Couple optimization strategy dedicated to orbital drilling, developed with MITIS Engineering and carried out on aluminium alloy 2024-T351. In order to enhance the mechanical behaviour of the system (fatigue, surface hardening…), an innovative mechanical surface treatment has been introduced for investigations: orbital roller burnishing, performed right after orbital drilling. The burnisher follows a helical path around the hole axis.…

Design and Development of Different Regenerative Braking Systems for a Commercial Electric Bus

Delhi Technological University-Lalit Kumar Choudhary, Kunal Mathur, Aditya Natu
  • Technical Paper
  • 2019-24-0208
To be published on 2019-08-15 by SAE International in United States
In today’s world, energy saving has become a crucial need for day to day operations. It is because of this need for development and enhancement of energy efficient technology, various industries and organizations are researching on ways to improve the energy savings, which would not only be holistic but also increase their own brand value in the market. A similar such method that can have an immense positive impact on conservation of energy is “Regenerative Braking”, which is now being implemented by various OEMs. With the help of this concept, a decelerating vehicle’s kinetic energy is harvested and stored for utilization at a later stage; instead of dissipating this useful energy as heat such as in the conventional braking system. Such a concept of extracting and storing energy can be utilized by the emerging electric vehicles to generate electric current that can be used for recharging the battery, powering the onboard appliances and increasing the range of these vehicles. The following paper describes the detailed study of a unique flywheel based regenerative braking system (f-RBS)…

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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Calculating the Estimated Fatigue Life of a Disc Spring

  • Magazine Article
  • TBMG-34573
Published 2019-06-01 by Tech Briefs Media Group in United States

In discussing fatigue life, it is important to distinguish between disc springs and conical spring washers, as they differ by design and intended usage. Conical spring washers are designed to provide a static thrust load in bolted joints and should not be used in fatigue applications; they are specified by DIN 6796.


Landing Gear Structural Health Monitoring

A-5 Aerospace Landing Gear Systems Committee
  • Aerospace Standard
  • AIR6168A
  • Current
Published 2019-05-23 by SAE International in United States

This SAE Aerospace Information Report (AIR) discusses past and present approaches for monitoring the landing gear structure and shock absorber (servicing), opportunities for corrosion detection, methods for transient overload detection, techniques for measuring the forces seen by the landing gear structure, and methods for determining the fatigue state of the landing gear structure. Landing gear tire condition and tire pressure monitoring are detailed in ARP6225, AIR4830, and ARP6137, respectively. Aircraft Brake Temperature Monitoring Systems (BTMS) are detailed in AS1145.


Flexure Testing of Hydraulic Tubing Joints and Fittings

G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
  • Aerospace Standard
  • ARP1185C
  • Current
Published 2019-04-23 by SAE International in United States
This SAE Aerospace Recommended Practice (ARP) establishes flexure test procedures to determine and classify the fatigue strengths of reconnectable or permanent hydraulic tube joints. The procedure is intended for conducting flexure tests of fittings and joints for hydraulic tubing materials such as AMS 5561 (21Cr-6Ni-9Mn) steel or AMS 4944 (3AL-2.5V) titanium. A mean stress is applied by holding system pressure in the specimens and flexing in a rotary or planar bending test machine.
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Minimizing Stress-Corrosion Cracking in Wrought High-Strength Aluminum Alloy Products

AMS D Nonferrous Alloys Committee
  • Aerospace Standard
  • ARP823F
  • Current
Published 2019-04-17 by SAE International in United States
The purpose of this recommended practice is to provide the aerospace industry with recommendations concerning minimizing stress-corrosion cracking (SCC) in wrought high-strength aluminum alloy products.
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Research on Dynamic Load of Belgian Event Based on Virtual Proving Ground

CATARC-Jiansen Yang, Xinyu Wang, Xin Li
Published 2019-04-02 by SAE International in United States
The fatigue load spectrum of the physical proving ground is the necessary input for fatigue life analysis of vehicle parts and components. It is usually obtained by Road Load Data Acquisition (RLDA) and loads decomposition using multi-body dynamics tools. Virtual Proving Ground (VPG) methodology is gradually replacing this technical strategy. The belgian road is the typical event in durability test, in this paper, the flexible body and FTire model are applied to the vehicle multi-body dynamics model in order to improve the simulation accuracy. The result shows that all the wheel center force, shock absorber displacement and axial force acquired by VPG simulation have excellent correlation with real vehicle measured data. It is also proved that the virtual proving ground technology is a reliable and effective method to obtain the fatigue load spectrum in the early stage of development.
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Accounting for Geometry and Residual Stresses in Weld Fatigue: A Strain Energy Density Approach to Total Life of Welded T-Specimens

John Deere-Peter Huffman
Published 2019-04-02 by SAE International in United States
Although many practical examinations of metal fatigue focus on crack initiation or crack growth, in practice many fatigue failures begin by initiating a crack which then grows until the part fractures completely or can no longer support the loads for which it was designed. This two-phase view of fatigue, called “total life”, is intended to aid engineers in designing parts that will meet design requirement while reducing unnecessary weight and cost. The challenge of using the total life to predict component life is magnified when components are welded together. This work, as a part of a larger project, examines the influence of the welding process on fatigue life predictability by predicting the life of welded specimens made from A36 steel as well as specimens machined from the same material using a geometry designed to develop a nearly identical stress distribution when loaded in the same way and comparing the predictions to measurements. Measured weld toe geometry and residual stresses were used and the results are employed in the relevant calculations. The methods used for predicting…
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Deriving Strain Based Local Structural Element Concept for the Fatigue Assessment of Additively Manufactured Structures

Fraunhofer Institute LBF-Rainer Wagener, Benjamin Möller, Tobias Melz, Matilde Scurria
Published 2019-04-02 by SAE International in United States
Additive manufacturing offers new options for lightweight design for safety parts under cyclic loading conditions. In order to utilize all advantages and exploit the full potential of additive manufactured parts, the main impact factors on the cyclic material behavior not only have to be identified and quantified but also prepared for the numerical fatigue assessment. This means in case of the AlSi10Mg aluminum alloy to consider influences related to the exposure strategy, heat treatment, microstructure, support structures and the surface conditions, as well as the influence of the load history and finally the interaction of these influences in order to perform a high quality fatigue assessment. Due to these reasons, and with respect to the numerical effort, the cyclic material behavior of additively manufactured AlSi10Mg produced by selective laser melting will be discussed. With respect to the microstructure, as well as the manufacturing process, a local structure element will be derived for the fatigue assessment. Thus, an influence that may be directly induced by the manufacturing process, like pores and different microstructures, can be considered…
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