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Unsettled Technology Domains in Aerospace Additive Manufacturing Concerning Safety, Airworthiness, and Certification

Muelaner Engineering, Ltd.-Jody Muelaner
  • Research Report
  • EPR2019008
To be published on 2019-12-20 by SAE International in United States
Additive manufacturing (AM) is currently being used to produce many certified aerospace components. However, significant advantages of AM are not exploited due to unresolved issues associated with process control, feedstock materials, surface finish, inspection, and cost. Components subject to fatigue must undergo surface finish improvements to enable inspection. This adds cost and limits the use of topology optimization. Continued development of process models is also required to enable optimization and understand the potential for defects in thin walled and slender sections. Costs are high for powder-fed processes due to material costs, machine costs, and low deposition rates. Cost for wire-fed processes are high due to the extensive post-process machining required. In addition, these processes are limited to low-complexity features. Incremental improvements in all of these areas are being made but a step change could potentially be achieved by hybrid processes, which use wire feedstock to deposit the bulk of the part and powder for fine detail. NOTE: SAE EDGE™ Research Reports are intended to identify and illuminate key issues in emerging, but still unsettled, technologies…
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Fundamentals of Fatigue Analysis

  • Professional Development
  • C1875
Published 2019-11-26

Fatigue is a structural failure mode that must be recognized and understood in order to develop products that meet life cycle durability requirements. Fatigue strength is an important design requirement in any new vehicle, particularly in the age of lightweighting as engineers struggle to meet stringent weight requirements without adversely impacting durability. This technical concept course provides an introduction to the fatigue failure mode and analysis methods. Attendees will learn about the physics of material fatigue, including damage accumulation which over time may progress to product failure. Attendees will also learn about fatigue analysis methods such as stress-life (SN), strain-life (EN), and crack growth, investigating the assumptions and applicability of each. This course includes example problems which are solved by hand calculation, exploring and reinforcing key concepts. Emphasis is placed on the practical aspects of these concepts and methods so attendees are prepared to put this knowledge into action. This course is popular with both experienced analysis engineers and with engineers transitioning into a durability or analysis role as it provides the needed foundation to develop effective fatigue prediction capabilities.

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STATISTICAL ANALYSIS OF LOW CYCLE FATIGUE PROPERTIES IN METALS FOR ROBUST DESIGN

General Motors Global Technical Center-Abolhassan Khosrovaneh
General Motors Technical Center India-Karthigan Ganesan, Biswajit Tripathy
  • Technical Paper
  • 2019-28-2576
Published 2019-11-21 by SAE International in United States
Objective: In ground vehicle industry, strain life approach is commonly used for predicting fatigue life. This approach requires use of fatigue material properties such as fatigue strength coefficient (σf'), fatigue strength exponent (b), fatigue ductility coefficient (εf'), fatigue ductility exponent (c), cyclic strength coefficient (K′) and cyclic strain hardening exponent (n′). These properties are obtained from stable hysteresis loop of constant amplitude strain-controlled uniaxial fatigue tests. Usually fatigue material properties represent 50th percentile experimental data and doesn't account possible material variation in the fatigue life calculation. However, for robust design of vehicle components, variation in material properties need to be taken into account. In this paper, methodology to develop 5th percentile (B5), 10th percentile (B10) and 20th percentile (B20) fatigue material properties are discussed. Possible material variation in fatigue life prediction is included as B5, B10 and B20 fatigue material properties. Methodology: Fatigue strength coefficient (σf') and fatigue strength exponent (b) are obtained by performing a linear regression on true stress amplitude (∆σ/2) versus reversals to failure (2Nf) in log-log scale. Fatigue ductility coefficient (εf')…
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Determine Thermal Fatigue Requirements for PEPS Antenna Copper Wire over Vehicle Lifetime with Defined Reliability Requirements

GMTCI-Abhinav Jauhri
  • Technical Paper
  • 2019-28-2582
Published 2019-11-21 by SAE International in United States
Reliability states the degree to which the result of a measurement, calculation, or specification can be depended on to be accurate. And, tests according to GM specifications represents a minimum of 15 years of vehicle life time with defined Reliability and Confidence level.In this work, actual number of thermal cycles for Thermal Fatigue tests (Thermal Shock and Power Temperature Cycle) are calculated for Copper Wire whose Coffin Manson exponent is 5.Overstressing the PEPS Antenna under thermal fatigue requirement (defined number of thermal cycles based on Reliability and Confidence requirements) will lead to broken Copper wire which will result in component’s functional failure and thus impossible to continue reliability testing.The objective of this paper is to determine thermal fatigue requirements for Antenna’s Copper wire whose Coffin Manson exponent is 5. Testing with exact number of thermal cycles will reduce the validation failures owing to broken Copper wire and thus save incurred revalidation cost.The current study is limited to only adjusting the thermal fatigue requirements (Number of Thermal Cycles) for only specific E/E components having Copper wire…
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Conceptualization and Modeling of a Flywheel-Based Regenerative Braking System for a Commercial Electric Bus

SAE International Journal of Commercial Vehicles

Delhi Technological University, India-Kunal Mathur, Lalit Kumar Choudhary, Aditya Manoj Natu, Krovvidi Srinivas, Vikas Rastogi
  • Journal Article
  • 02-12-04-0018
Published 2019-11-19 by SAE International in United States
The following article illustrates the detailed study of the development of a unique flywheel-based regenerative braking system (f-RBS) for achieving regenerative braking in a commercial electric bus. The f-RBS is designed for installation in the front wheels of the bus. The particular data values for modeling the bus are taken from multiple legitimate sources to illustrate the development strategy of the regenerative braking system. Mechanical components used in this system have either been carefully designed and analyzed for avoiding fatigue failure or their market selection strategies are are explained. The positioning of the entire system is decided using MSC Adams View®, hence determining a suitable component placement strategy such that the f-RBS components do not interfere with the bus components. The entire system is modeled on MATLAB Simulink® with sufficient accuracy to get various results that would infer the performance of the system as a whole. The overall efficiency of the developed system in terms of battery consumption is also computed in this study.
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Additively Manufactured Component Substantiation

AMS AM Additive Manufacturing
  • Aerospace Standard
  • AIR7352
  • Current
Published 2019-10-31 by SAE International in United States
This AIR is applicable to components fabricated using additive manufacturing (AM) processes. The discussion is generic with respect to specific additive processes as much as possible. Each additive process has unique considerations that should be addressed in any effort to substantiate additively manufactured components, This specification is written for metallics but conceptually could be applied to non-metallics.
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Design Analysis and Simulations of Components of an All-Terrain Vehicle

BITS Pilani-Pranjal Shukla, Konark Joshi, Utkarsh Rastogi, Ajith Reddy Moola
Published 2019-10-11 by SAE International in United States
A single seater All-Terrain Vehicle (ATV) is conceptualized in this paper which covers the extent of designing and simulations ranging from static structural, fatigue analysis, explicit dynamics etc. Solidworks and Ansys Workbench have been used as the tools for the simulation. Our aim was to design and fabricate a vehicle which is light weight (<200Kgs), easily maneuverable in harsh driving conditions and also scores high in affordability and maintenance.This report also contains the design consideration of the chassis, steering, suspension, braking, powertrain. Simulation results of components like hubs, knuckles, A-Arms, chassis are done with special focus on modelling based on real time forces and behaviors. MATLAB Simulink models are used and explained for the suspension model.The vehicle was fabricated in-house using various fabrication methods of TIG Welding, Vertical CNC machines etc. The strength tests for the specimens of welding were checked for the safety of the chassis. The vehicle was tested on tracks for braking, steering and acceleration and further modifications were made in the design to incorporate the iterations.
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Design Analysis and Development of High-Speed Rotating Fatigue Testing with Integrated by Twisting Test

Avinash Prakash Barve, Rahul Jangam, Adm Aman Soni, Pravin Pandagre, Hardik Bhautkar, Bhushan Chapke, Shantanu Bankar, Faisal Hussain, Adm Paresh Setiya
Published 2019-10-11 by SAE International in United States
The fatigue testing machine mostly used for industrial or laboratory applications are limited to performing single fatigue tests with high leading cost. In the present paper the experimental setup of the traditional fatigue testing machine is integrated with torsional test, to experimentally study the effect of fluctuating stresses on the material under service. In contradiction to earlier machines, the machine herein developed provides uniform bending and twisting moment distribution along the length of the test specimen. The machine performs fatigue test and torsional test, which provides the extreme force needed to understand the properties and behavior of materials. The machine consists of an electric motor to provide the required torque and two circular arms with adjustable chucks to fit test samples of various sizes. The machine provides computerized data for failed samples with data pertaining to each sample. The experimental model is designed and fabricated to match our customers unique test objective. Fatigue failures are reported 75% of documented materials failure and occur catastrophically. Fatigue life can be tested on loading conditions and it is…
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Systematic Work Flow for Fatigue Life Prediction of Automotive Components

Mahindra & Mahindra, Ltd.-Nitin Kumar Khanna, Baskar Anthonysamy, Krishna Shettipally, Manohar Kalal
Published 2019-10-11 by SAE International in United States
Fatigue life estimation of automotive components is a critical requirement for product design and development. Automotive companies are under tremendous pressure to launch new vehicles within short duration because of customer’s changing preferences. There is a necessity to have a comprehensive virtual simulation and robust validation process to evaluate durability of vehicle as per customer usage. Test track and field test are two of the most time-consuming activities, so there is a need of simulation process to substitute these requirements. This paper summarizes the overall process of Accelerated Durability Test with measured road loads. Based on category of vehicle, type road profiles and the customer usage pattern, the wheel forces, strains and acceleration are measured which is used to derive the equivalent duty cycles on proving ground. The wheel force transducers (WFT) are used to derive loads for fatigue life estimation. A full vehicle model is prepared in ADAMS CAR and validated through Physical testing. The loads on suspension hard points extracted from the validated MBD model. These loads at various hardpoint locations, are used…
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Critical Wear Assessment of AA8011/Hybrid Metal Matrix Composites with Surface Amendment Using Friction Stir Process

Sri Krishna College of Engg. and Tech.-Soundararajan Ranganathan, Shri Vignesh Ramachandran, Ramprakash Palanivelu, Saravanakumar Ramasamy
Published 2019-10-11 by SAE International in United States
Friction Stir Process (FSP) was employed for surface modification of steel, titanium, aluminum and magnesium-based alloy has been significantly revised through the last decade. Friction Stir Process can improve surface properties such as hardness, abrasion resistance, ductility, strength, fatigue life, corrosion resistance and formability without upsetting the bulk properties of the material. The aluminum alloy having low ductility and softness characteristics are restricted because of their poor tribological properties. Preliminary studies reveal that, an ideal circumstance is to improve the aluminum alloy material life cycles by the way of strengthening the surface layer which can be modified through reinforcing nanoparticles through FSP. The main objective of the study is to improve the surface properties of AA8011 by adding nanoparticles such as SMA and silicon nitrate (Si3N4) through friction stir process. By the way, this experiment was carried out to obtain three set of samples like virgin AA8011, AA8011 with shape memory alloy and AA8011 along with shape memory alloy and silicon nitride during FSP under optimal process parametric condition. The nanoparticles distribution was improved after…
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