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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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Effect of Geometry Variation in a Polymer Electrolyte Membrane Fuel Cell

Siemens Digital Industries Software-Carlo Locci, Chris Lueth, Huong Nguyen, Karin Frojd
  • Technical Paper
  • 2020-01-1174
To be published on 2020-04-14 by SAE International in United States
Water transport at high current densities is of main concern for polymer electrolyte membrane (PEM) fuel cells. The water content of the membrane must be high enough to provide maximum electrical conductivity and thus optimal stack performance. Dry-out may also lead to membrane degradation. However, a too high level of humidity leads to cell flooding, blocking the air and fuel flows to the catalyst sites and thus the reactions, resulting in a drop-in efficiency. Fuel cells water transport physics requires further investigation due to its complexity [1,2] and numerical modelling can improve the fundamental understanding of the phenomena. In this work, a 3D comprehensive model for fuel cells is presented. The PEM fuel cell is modelled in Siemens Simcenter STAR-CCM+ [3]. Anode and cathode GDL are modelled as porous media, with electrochemical reactions calculated in an infinitely thin catalyst layer. The membrane is modelled as a solid block including proton and water transport with electro-osmotic drag as well as ohmic heating. A two-phase approach is used to model the gas mixture and liquid water transport…
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LOW COST ELECTROMAGNETIC SHIELDING MATERIAL BASED ON POLYPYRROLE-BIO WASTE COMPOSITES

Dongguk University-Ganapathi Nagarajan
Hindustan University-Sheeba Rathina Selvi, Srimathi Krishnaswamy, Puspamitra Panigrahi
  • Technical Paper
  • 2020-01-0226
To be published on 2020-04-14 by SAE International in United States
There is a crucial need of Electromagnetic interference shielding in many of the applications in this digital world with low cost and high efficient shielding materials. Electrically conducting heterocyclic polymer polypyrrole has found its application as an EMI shielding materials due to its conducting property. Electrically conducting polypyrrole (PPy) coated on coconut fibres (coir) with different morphology, were prepared through in-situ chemical polymerization of PPy using strong oxidizing agent like ammonium per sulfate. The synthesized PPy on coconut fibre were characterised using UV-Visible spectrophotometer(UV-VIS) and Fourier transform infrared spectroscopy (FTIR) which confirmed the product formation. The morphology was done using Scanning electron Microscopy(SEM).Thermal studies were performed by Thermo Gravimetric analysis (TGA). The effect of PPy morphology and content in composite with coir on the DC conductivity and shielding effectiveness (SE) were investigated. The shielding effectiveness was calculated theoretically and well matched with the experimental values.
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Investigation of the operating conditions on the water and thermal management for a polymer electrolyte membrane fuel cell by one-dimensional model

Tongji Universtiy-Xuhui Wang, Yaqian Dong, Sichuan Xu
  • Technical Paper
  • 2020-01-0856
To be published on 2020-04-14 by SAE International in United States
Water and thermal management is an essential issue that influences performance and durability of a polymer electrolyte membrane fuel cell (PEMFC). Water content in membrane decides its ionic conductivity and membrane swelling favors the ionic conductivity, resulting in decreases in the membrane’s ohmic resistance and improvement in the output voltage. However, if excessive liquid water can’t be removed out of cell quickly, it will fill in the pores of catalyst layer (CL) and gas diffusion layer (GDL) then flooding may occur. It is essential to keep the water content in membrane at a proper level. In this work, a transient isothermal one-dimensional model is developed to investigate effects of the relative humidity of inlet gas and cell temperature on performance of a PEMFC. Comprehensive physical and chemical phenomenon inside the cell is included, especially the mass transfer of hydrogen, oxygen, vapor and liquid water in gas channels, GDL and CL and non-frozen membrane water in ionomer. Phase change between vapor and liquid water is also considered. The cell’s performances at the conditions of the different…
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A McPherson Lightweight Suspension Arm

Barnem Tecnologie Plastiche Srl-Marcello Chessari
Metal-Stampi di Maccarinelli e Cucchi-Silvia Maccarinelli
  • Technical Paper
  • 2020-01-0772
To be published on 2020-04-14 by SAE International in United States
The paper deals with the design and manufacturing of a McPherson suspension arm made from short glass fiber reinforced polyamide (PA66). The design of the arm and the design of the molds have been made jointly. According to Industry 4.0 paradigms, a full digitalization of both the product and process has been performed.Since the mechanical behavior of the suspension arm strongly depends on constraints which are difficult to be modelled, a simpler structure with well-defined mechanical constraints has been developed. By means of such simple structure, the model for the behavior of the material has been validated. Since the suspension arm is a hybrid structure, the associated simple structure is hybrid as well, featuring a metal sheet with over-molded polymer. The issues referring to material flow, material to material contact, weld lines, fatigue strength, high and low temperature behavior, creep, dynamic strength have been investigated on the simple structure. The detailed understanding gained with the simple structure has been transferred on the actual suspension arm.The McPherson arm has been produced and withstood the technical specifications.
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Development of Intercooler Hose for Future Engine

Hino Motors, Ltd.-Ryoji Kodama, Takahiro Onishi
  • Technical Paper
  • 2020-01-0236
To be published on 2020-04-14 by SAE International in United States
Current intercooler hoses, which are made from fluorocarbon rubber (FKM) and silicone rubber (VMQ) exhibit high heat resistance and durability. However, they will be used in more severe use environments, and there is a risk of problems arising with their current material composition. This investigation into issues concerning intercooler hoses in future engines found that FKM mechanical properties were insufficient under high temperature environments. In this research, efforts to improve the mechanical properties of FKM focused on the low durability of the internal FKM crosslinking points as the cause of this insufficiency. The current crosslinking method has excellent acid resistance and cannot be modified. An effective improvement the properties was therefore sought by adding a new distinct crosslinking network while preserving the current level of acid resistance of the existing network. Carbon black gel was used as a reinforcing agent to form the new network. Polymer types and blending were adjusted to achieve the target values and develop a new FKM, which was used to make a prototype hose and confirmed to be free of…
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Effects of Helical Carbon Nanotubes on Mechanical Performance of Laminated Composites and Bonded Joints

Wichita State University-Ramanan Sritharan, Davood Askari
  • Technical Paper
  • 2020-01-0029
Published 2020-03-10 by SAE International in United States
Most composite assemblies and structures generally fail due to weak interlaminar properties and poor performance of their bonded joints that are assembled together with an adhesive layer. Adhesive failure and cohesive failure are among the most commonly observed failure modes in composite bonded joint assemblies. These failure modes occur due to the lack of reinforcement within the adhesive layer in transverse direction. In addition, the laminated composites fail due to the same reason that is the lack of reinforcement through the thickness direction between the laminae. The overall performance of any composite structures and assemblies largely depends on the interlaminar properties and the performance of its bonded joints. Various techniques and processes were developed in recent years to improve mechanical performance of the composite structures and assemblies, one of which includes the use of nanoscale reinforcements in between the laminae and within the adhesive layer. However, most prior research has been focused on use of straight carbon nanotubes (CNTs) and other nanomaterials in particle forms. The goal of this research was to improve the properties…
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BEARING, BALL, AIRFRAME, ANTI-FRICTION, HEAVY DUTY

ACBG Rolling Element Bearing Committee
  • Aerospace Standard
  • AS27640E
  • Current
Published 2020-03-04 by SAE International in United States
No Abstract Available.
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Conductive Polymer/Carbon Nanotube Structural Materials

  • Magazine Article
  • TBMG-36172
Published 2020-03-01 by Tech Briefs Media Group in United States

Carbon nanotubes (CNTs) show promise for multifunctional materials for a range of applications due to their outstanding combination of mechanical, electrical, and thermal properties. These promising mechanical properties, however, have not translated well to CNT nanocomposites fabricated by conventional methods due to the weak load transfer between tubes or tube bundles.

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Production Method for High-Performance Polymer

  • Magazine Article
  • TBMG-36197
Published 2020-03-01 by Tech Briefs Media Group in United States

A method was developed to produce a polymer material called PBO — known commercially as Zylon — that’s used in bulletproof vests and other high-performance fabrics. The new approach could be useful in making PBO products that resist degradation — a problem that has plagued PBO-based materials in the past.