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Micro-Macro Acoustic Modeling of Heterogeneous Foams with Nucleation Perturbation

Duke University-Johann Guilleminot
Ecole des Ponts ParisTech-Michel BORNERT
  • Technical Paper
  • 2020-01-1526
To be published on 2020-06-03 by SAE International in United States
The properties of a polyurethane foam are greatly influenced by the addition of graphite particles during the manufacturing process, initially used as a fire retardant. These thin solid particles perturbate the nucleation process by generating bubbles in its immediate vicinity. The preponderance of work so far has focused on foams that are locally relatively homogeneous. We propose a model for locally inhomogeneous foams (including membrane effects) consisting of a random stack of spheres that permits one to represent certain pore size distribution functions. The cellular structure of the foam is obtained through a Laguerre tessellation and the solid skeleton determined from the minimization of surface energy (Surface Evolver). The structure of real foam samples is analyzed using X-ray computed tomography and scanning electron microscopy followed by image processing to create computerized three-dimensional models of the samples. The corresponding effective material parameters, including the permeability, the tortuosity and the viscous characteristic length are computed by applying a numerical homogenization approach. All the numerical data are presented, discussed and further compared with experimental results.
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Microstructure-Fatigue Property Relationships for Cast Irons

National Research Council (Canada)-Xijia Wu
  • Technical Paper
  • 2020-01-0187
To be published on 2020-04-14 by SAE International in United States
Cast irons are widely used for combustion engine/exhaust system applications, not only because they are less expensive but also because they offer some attractive properties such as good thermal conductivity, relatively high specific yield strength, and good oxidation resistance. Cast irons can be made with a wide variety of microstructures containing either flake-like graphite (FG), nodular graphite (NG) or vermicular graphite (VG), or mixing of the above, which control their mechanical and fatigue properties. In this paper, a microstructure-fatigue property relationship model is developed, combining the Tanaka-Mura-Wu’s fatigue crack nucleation model with Eshelby’s solution for materials containing ellipsoidal inclusions. This applies to cast irons considering its microstructural graphite characters (shape, size, elastic modulus and Poisson’s ratio). This model is used to analyse ductile cast iron (DCI) with nodular graphite (NG) microstructure, grey cast iron (GCI) with flake-like graphite (FG) microstructure, and compacted graphite iron (CGI) with vermicular graphite (VG) microstructure. Excellent agreement is found between the model prediction and the experimental data or the Coffin-Manson-Basquin correlations at room temperature. Further development will be to incorporate…
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A New Appraisal of the Thermomechanical Behaviour of a Hybrid Composite Brake Disc in a Formula Vehicle

Force Motors-Pradeep Chandrasakaran
Sri Krishna College of Engineering and Technology-Soundararajan Ranganathan, Sathishkumar Kuppuraj, Shanthosh Gopal
  • Technical Paper
  • 2019-28-2572
Published 2019-11-21 by SAE International in United States
The present work promotes a hybrid composite brake disc for thermal and structural analysis of a formula vehicle. In order to reduce the un-sprung weight without compromising the strength, hybrid composite materials were incorporated in the disc plates of the braking system. In the disk brake system, the disc is a major part of a device used for slowing or stopping the rotation of a wheel. Repetitive braking of the vehicle leads to heat generation during each braking condition. Based on the practical understanding the brake disc was remodeled with unique slotting patterns and grooves, using the selected aluminium alloy of (AA8081) with reinforcement particle of 15wt% Silicon carbide (SiC) and 3wt% Graphite (Gr) as a hybrid composite material for this proposed work. By varying slotting pattern and groove angles the transient thermal and structural analysis using ANSYS workbench on the hybrid composite disc plate of disk brake is done. The main purpose of this study is to analyse the thermomechanical behavior of composite brake disc for a formula vehicle under severe braking conditions. To…
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Trace Element Control Nickel Alloy Castings

AMS F Corrosion Heat Resistant Alloys Committee
  • Aerospace Material Specification
  • AMS2280D
  • Current
Published 2019-11-05 by SAE International in United States
This specification establishes testing methods and maximum permissible limits for trace elements in nickel alloy castings.
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Exploration of Dry Sliding Wear Behaviour of Sisal Fiber Reinforced Cashew Nut Shell Liquid and Epoxy Polymer Matrix Composite as an Alternative Friction Material in Automobiles

Sri Krishna College of Engg. and Tech.-Soundararajan Ranganathan, Shanthosh Gopal, Tharunkumar Magudeeswaran, Ramamoorthi Rangasamy
Published 2019-10-11 by SAE International in United States
The brake pad is one of the foremost imperative parts of the vehicle. Due to the environmental requirement, natural materials were the alternate source for products manufacturing. The product composite made by using hot press techniques with mixing ingredients such as natural fiber (treated sisal), cashew nut filler, graphite and alumina with resin (cashew nut shell liquid - CNSL and epoxy). Two formulas and four samples of each set were composed by varying the resin type of CNSL and epoxy and prepared the test samples with attaining better hardness. The main intern of this proposed effort is to appraise the wear in dry sliding and performance of friction of the prepared composites. The composites are taken for tribo test by varying the load of 10,20,30,40 N and sliding distance of 1000, 2000 m respectively. Experiments were performed at stated process parametric conditions to record the responses. The result shows that the CNSL resin composites specific wear resistance and frictional coefficients are found better than epoxy resin composites. The addition of filler element cashew nut shell…
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Creation of an Icephobic Coating using Graphite Powder and PTFE Nanoparticles

University of Notre Dame-Joseph Gonzales, Hirotaka Sakaue
Published 2019-06-10 by SAE International in United States
Ice accretion can cause numerous inefficiencies, structural stresses, and failures in applications ranging from building design to power generation and aerospace applications. Currently, some of the leading de-icing technologies, such as the ICE-WIPS system, utilize a heating element coupled with a superhydrophobic surface. The high power consumption inherent in these systems can make them expensive and impractical, especially when coupled with power generating systems. Reduced power consumption in these de-icing technologies can be achieved through increased absorption of solar radiation in the visible range while maintaining hydrophobic performance of a coating. In this work, a Polytetrafluorethylene (PTFE) and graphite-based superhydrophobic surface is proposed, which maintains similar hydrophobic performance to standard superhydrophobic surfaces. The novel coating demonstrates contact angles of upwards of 130o and sliding angles of less than 4o, while increasing solar radiation absorption in the visible range by approximately 139% over PTFE-based hydrophobic coatings. Icing wind tunnel tests where the coatings were exposed to visible light in order to simulate solar radiation were performed in a variety of different conditions in order to verify…
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Open Access

Monotonic and Cyclic Creep of Cast Materials for Exhaust Manifolds

SAE International Journal of Materials and Manufacturing

Royal Institute of Technology, Sweden-Christian Öberg, Stefan Jonsson
Scania, Sweden-Baohua Zhu
  • Journal Article
  • 05-12-02-0012
Published 2019-05-13 by SAE International in United States
Cast materials are creep tested between 600 and 900°C using three methods: (i) tensile testing at different strain rates, (ii) stress relaxation during thermal cycling and (iii) traditional creep tests at constant load. Comparisons are made between fast and slow methods and between monotonic and cyclic deformation modes. The tested materials, SiMo51, SiMo1000, Ni-resist D5S and HK30, are used for exhaust manifolds in heavy-duty diesel engines. The fast and cheap methods, (i) and (ii), were used on all materials, while the tedious and costly method, (iii), was used on SiMo51 only. The creep rates from monotonic tensile tests and stress relaxations during thermal cycling agree well. There is no difference between monotonic and cyclic creep rates, and cyclic rates are practically unchanged with the number of thermal cycles. No or small differences in creep rates are observed when comparing tension and compression, although three of the materials include large graphite nodules. At 700°C, a Norton plot for SiMo51 shows coinciding results for tensile test and compressive stress relaxations, whereas the minimum creep rates from constant…
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Multidisciplinary Design Analysis and Optimization of Aerospace Composites

Charles Lu
  • Progress In Technology (PT)
  • PT-201
Published 2019-04-30 by SAE International in United States
Multidisciplinary Design and Optimization of Aerospace Composite Materials is a collection of ten SAE technical papers focusing on the design analysis of aerospace composite structures from the perspective of various disciplines. The book concentrates on the following aspects: • Analytical methods for weight design of aircraft structures, including a parametric geometry model capable of generating dedicated models for both aerodynamic and structural solvers. • Methodologies for evaluating the structural performance of carbon/epoxy composite panels. • An aerodynamic design of flexible wings made of composite structures. • Thermal design and analysis of composite enclosures. • Methodologies for analyzing the acoustic performance of composite structures, including the design optimization method to evaluate the acoustic performance in terms of transmission loss (TL) of various composite panels. • The lightening effect on composites, presenting a theoretical method to compute the electrical current propagating through composite structures due to lightning strikes. • The issue of fire resistance as most polymer resins are flammable once the respective ignition temperatures are reached. • A probabilistic-based reliability analysis of the composite structures. The…
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Analysis of Tribofilm Formed by Electric Brush Sliding for Long Life Starter Motor

DENSO Corporation-Taro Fukuda
Published 2019-04-02 by SAE International in United States
Global exhaust emission regulations are becoming stricter, and vehicles equipped with the idle stop system (ISS) are increasing. Recently, starters for vehicles equipped with ISS are required to improve operation feel when speedily restarted. To satisfy this demand, starters must rotate at higher rotational speeds, and heavier wear in their brushes may cause problems. Tribofilm formed on commutators surface by the brush sliding is an important factor in the brush commutator wear, because tribofilm is said to have a property to increase lubricity and decrease mechanical wear in brushes and commutator, as well as to improve commutation and decrease arc wear. Therefore, for reducing brush commutator wear, it is considered effective to promote film formation by improving materials. However, few researches have been conducted to evaluate the relationship between brush materials and tribofilm formation. In this research, we investigated the influence of the brush materials on tribofilm formation and its mechanism. We conducted brush durability tests changing the amount of WS2 and the kind of graphite, and analyzed the hardness of the tribofilm formed by…
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Evaluation of friction coefficient of lamellar and compacted graphite irons in lubricated ring-on-cylinder system

Tupy S.A., Joinville - SC, UDESC, Joinville - SC.-Wilson Luiz Guesser
Universidade Tecnológica Federal do Paraná - UTFPR - Campus-Carlos Henrique da Silva, Giuseppe Pintaúde
Published 2018-09-03 by SAE International in United States
The current investigation compares the friction behavior between specimens extracted from engine blocks of grey cast iron (class FC 250 ABNT NBR 6589 standard) and compacted graphite iron (class GJV450 ISO 16112 standard). The effect of wall thickness was evaluated, by extracting samples from regions equivalent to two levels of thickness. The piston ring used was a nitrided martensitic stainless steel with an asymmetric profile, and the lubricant oil was the SAE 30 CF. The tribological tests were conducted at 75 N normal load for a duration of 1 hour, a frequency of 5 Hz and a stroke of 10 mm. The tests were carried out at a controlled temperature of 40° C. In a general way, the compacted graphite irons presented smaller friction coefficients when compared to that observed for the lamellar ones; and the wall thickness showed relevance only for the compacted graphite iron, being the lowest values found for the thinner wall. On the other hand, for the grey cast iron, the wall thickness did not affect significantly the friction behavior. Finally,…
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