The Tiltrotor Test Rig (TTR) is a NASA project, joint with the U.S. Army and Air Force, to develop a new, large-scale proprotor test system for the National Full-Scale Aerodynamics Complex (NFAC). The first wind-tunnel entry was completed in November 2018 with a modern, 26-ft diameter proprotor. The primary purpose was to complete the development of the TTR, including systems integration with the NFAC. The TTR and rotor were tested up to 273 knots in axial flow. This is the highest airspeed ever achieved by a full-scale proprotor in any wind tunnel. Extensive conversion-mode data were also acquired, and hover/climb conditions were explored. Additional testing included aerodynamic tares, motor tests, thermal tests, modal vibration tests, and other checkout activities. This paper summarizes the results of the test, including examples of the most significant data.

W., C., Sheikman, Alex, Norman, Thomas

Effects of Temperature on Mechanical Response of Lithium Ion Batteries to External Abusive Loads

2019-01-10024/2/2019

This paper focuses on mechanical properties of lithium ion batteries subjected to mechanical loading. Researchers have studied mechanical properties of batteries under room temperature. However, the operating temperature for these cells can change from -20 to +60 degrees Celsius. Therefore, characterization of cell’s response under varying temperature is of utmost importance. We have tested battery components and cells at a range of temperatures and have documented the changes in mechanical properties. Our results show that extreme hot or cold temperatures can have a significant effect on the mechanical response of lithium ion batteries under crush and indentation.

Gilaki, Mehdi, Sahraei, Elham

The Heat Is On: A Guide to Specifying Insulation Materials

TBMG-339193/1/2019

One of the first things an electrical engineer will learn is that the number-one enemy of designing and manufacturing any electrical/electronic product is heat. It's the one characteristic that can cause your idea of a hand-sized unit to turn into a tabletop unit. When discussing insulation with a manufacturer, the first question that seems to come up is temperature resistance. It is a very important characteristic but there are a few others that need to be addressed as well. In addition to temperature rating, voltage along with mechanical strength play a very important role in the selection of insulation.

Microscopy Technique Works at Extreme Heat

TBMG-335881/1/2019

A stainless steel alloy — alloy 709 — has potential for elevated-temperature applications such as nuclear reactor structures. It is exceptionally strong and resistant to damage when exposed to high temperatures for long periods of time, making it a promising material for use in next-generation nuclear power plants.

Study on Brake Disc Dynamics under Asymmetric Thermal Loads

2018-01-190110/5/2018

In order to explore the generation mechanism of hot-spots on the automotive brake disc, disc tests under non-frictional thermal loads are carried out on the brake dynamometer test bench. In the tests, the oxy-acetylene flame is used as the heat source, and the distribution characteristics of the disc temperature and displacement are measured and analyzed. To confirm the mechanism of the disc deformation, a disc thermal buckling model using finite element method is established, and the key factors for the disc thermal buckling under thermal loads are further analyzed. It is found that the temperature circumferential gradient is small but the temperature radial gradient is large. The disc presents waviness deformation mode with 5th order in circumferential direction, which is the first thermal buckling mode of the disc. A method using spatial frequency spectrum has been proposed to find the critical time and load of thermal buckling. The heat source power and the rotational speed have no significant influence on the temperature and displacement circumferential and radial distribution of the disc. The temperature radial gradient is the main reason for the disc thermal buckling. The larger the temperature radial gradient is, the more easily the disc thermal buckling occurs.

Meng, Dejian, Liu, Jialin, Zhang, Jingyi, Zhang, Lijun

Mechanical Splice for Aerospace Fiber Optic Cables

AS5405 (Current)9/7/2018

This document defines performance standards which mechanical fiber optic cable splices must meet to be accepted for use in aerospace platforms and environments.

AS-3 Fiber Optics and Applied Photonics Committee

Fusion Splice for Aerospace Fiber Optic Cables

AS6506 (Historical)9/7/2018

This document defines performance standards which fiber optic cable splices must meet to be accepted for use in aerospace platforms and environments.

AS-3 Fiber Optics and Applied Photonics Committee

Optical Interconnect Design Challenges in Space

TBMG-329069/1/2018

More and more aerospace applications are incorporating fiber optics technology into their designs due to its many advantages over copper. The thinner fiber solutions provide higher speed over a longer distance, are more reliable, offer higher noise immunity and, in many cases, lower the cost of ownership. Additionally, for the same diameter, fiber can pack more data than copper. Fiber is faster than the category 5 and 6 copper cables, approaching the speed of light (31% lower). For copper, pushing the speed beyond 1G is a challenge, but for fiber 10G is quite common. Copper is limited by distance. Usually, signal degradation with copper will occur after about 90 meters (2.7 km maximum for custom systems), while fiber can achieve more than 1.5 km without a problem and can deliver over 80 km depending on transmission signal quality.

Tiny Probe Can See and Measure Body Temperatures

TBMG-290096/1/2018

A new probe developed at the University of Adelaide, may help researchers find better treatments to prevent drug-induced overheating of the brain, and potentially refine thermal treatment for cancers.

Enhanced Low-Order Model with Radiation for Total Temperature Probe Analysis and Design

01-11-01-00035/16/2018

Analysis and design of total temperature probes for accurate measurements in hot, high-speed flows remains a topic of great interest in aerospace propulsion and a number of other engineering areas. One can apply detailed computational methods for simultaneous convection, conduction and radiation heat transfer, but such approaches are not suitable for rapid, routine analysis and design studies. For these studies, there is still a place for low-order approximate methods, and that is the subject of this article. Here, an enhanced, low-order model is presented that includes conduction with variable thermal conductivity, convection with varying convection coefficient, varying diameter (and thus area) along the length of the sensor and radiation, all implemented in a convenient MATLAB code. We have also developed a new novel procedure to integrate the enhanced low-order model with computational fluid dynamics/conjugate heat transfer (CHT/CFD) simulations to accurately predict the important influences of radiation under different conditions in a very efficient manner.

Vincent, Tyler, Schetz, Joseph, Lowe, K. Todd

Technique Measures Temperature of 2D Materials at the Atomic Level

TBMG-288695/1/2018

Newly developed two-dimensional (2D) materials such as graphene — which consists of a single layer of carbon atoms — have the potential to replace traditional microprocessing chips based on silicon, which have reached the limit of how small they can get. But engineers have been stymied by the inability to measure how temperature will affect these new materials, collectively known as transition metal dichalcogenides (TMDs).

Development of a Thermal Fatigue Test Bench for Cylinder Head Materials

2018-01-14104/3/2018

An innovative specimen design and test system for thermal fatigue (TF) analysis is developed to compare the fatigue behavior of different cylinder head materials under realistic cyclic thermal loadings. Finite element analyses were performed to optimize the specimen geometry and thermal cycles. The reduced section of the TF specimen is heated locally by a high frequency induction heater and cooled by compressed air. The mechanical strain is then induced internally by the non-uniform thermal gradient generated within the specimen to closely simulate what valve bridges in cylinder heads experience in real operation. The resulting fatigue life is a function not only of the inherent fatigue resistance of the alloys, but also of other relevant properties such as thermal conductivity, modulus of elasticity, and coefficient of thermal expansion. This test is an essential tool for comparing different alloys for thermal fatigue applications. In this paper, four aluminum alloys were tested to investigate the effect of the compositional change and heat treatment on the thermomechanical performance. The test method and results will be presented in detail.

Lai, Wei-Jen, Engler-Pinto, Carlos

Phonon Confinement Effect in TiO2 Nanoparticles as Thermosensor Materials

TBMG-287894/1/2018

TiO2 or ZnO nanoparticles (NPs) have a very strong finite-size dependency in their Raman spectra or photoluminescence (PL) spectra due to the phonon confinement effect or the quantum confinement effect. Together with a fast grain growth kinetics and a high stability under high temperature and pressure, they can forensically retain the complete thermal history of an event. By spatially distributing these NPs during thermal events such as blasts or weapon tests, a spatially and temporally non-uniform thermal environment can be determined by a direct read off their Raman or PL spectra at various locations.

Infrared Testing

J359_201801 (Current)

1/9/2018

The scope of this SAE Information Report is to provide general information relative to the nature and use of infrared techniques for nondestructive testing. The document is not intended to provide detailed technical information, but will serve as an introduction to the theory and capabilities of infrared testing and as a guide to more extensive references.

Metals Technical Committee

Adam Sidor, NASA Research Fellow, Georgia Institute of Technology, Atlanta, GA

TBMG-271026/20/2017

Thermal Protection Systems (TPS) — heatshields — form the outer surface of spacecraft and provide protection as the vehicle plunges through planetary atmospheres. Conformal ablative materials are currently being developed to improve TPS performance. Adam Sidor is developing a fresh approach to designing and manufacturing these materials to produce larger tile sizes while reducing labor, cost, and waste.

A Numerical Study of Radiator Performance under a Transient Thermal Cycle

2017-01-06233/28/2017

Radiator thermal cycle test is a test method to check out the robustness of a radiator. During the test, the radiator is going through transient cycles that include high and low temperature spikes. These spikes could lead to component failure and transient temperature map is the key to predict high thermal strain and failure locations. In this investigation, an accurate and efficient way of building a numerical model to simulate the transient thermal performance of the radiator is introduced. A good correlation with physical test result is observed on temperature values at various locations.

Wang, Zun, Zhang, Yi, lenormand, Christophe, Ansari, Mohammed, Henner, Manuel

Acoustical and Thermal Materials Test Procedure

J1324_201608 (Current)8/2/2016

Acoustical Materials Committee

Thermal Performance of Disc Brake and CFD Analysis

2014-01-24979/28/2014

In this paper an effective technology of virtual thermal test of disc brake with several advanced analytic techniques was presented. With the virtual thermal test process, thermal performance of brake system could be easily evaluated without any possibility of great errors that used to happen in the past. In addition to the classical result of CFD, this virtual thermal test produced several valuable applications such as thermal deformation of rotor, optimization of thermal performance and estimation of braking distance.

Choi, Bongkeun

Effect of Thermal Behavior of Friction Materials on Brake Squeal

2014-01-25149/28/2014

Brake noise is an emerging concern in Indian Auto-industry; with brake squeal being the most evident form of brake NVH. Squeal noise generation attributes to many parameters including kinematics of braking parts during pressure application, structural dynamic behavior which in turn depends on coupling at resonant frequencies of different parts of a brake assembly, material of brake parts, operating clearances in the mating parts etc. The genesis of brake squeal lies in the generation of unstable frictional forces during braking event. These frictional forces induce uncontrolled amplification of brake parts vibration, which in turn tend to produce perceivable sound or noise. The magnitude this vibration induced squeal depends on co-efficient of friction, braking pressure, speed and temperature of friction material. It is known from typical squeal evaluations on dynamometer that at different temperatures of friction, the ability/ occurrence, of squeal is different, typically in the range of 50°C to 200°C. This could be linked to the thermo-elastic behavior of friction, as it is a heterogeneous material comprising thermally sensitive raw contents as compared to other parts of brake assembly which are largely a base of iron and less sensitive to change elasticity in above temperature range. The change in elastic behavior of friction can shift the resonant frequencies of pads/shoes and hence affect propensity of the squeal for a given brake. This behavior of friction needs an objective judgment, especially with different types of fiction materials like NAO, Low Metal, Semi-Metallic used in automotive brake applications. This paper focuses on comparative analysis carried out on two identified brakes viz. a disc brake (of an SUV) and a drum brake (of a small car) using 3 different friction parts per brake for NAO and low metal type. The thermal behavior of friction in terms of shift in resonant frequencies of pads/shoes and associated change in modal loss factor, as a measure of structural damping at identified temperatures, have been objectively compared between different grades for a given brake type. Its significance towards brake noise has been discussed.

Mahale, Prashant, Bohari, Aziz, M P, Raajha

Characterization of PU Foam for High Temperature Applications in Automobiles

2014-01-10354/1/2014

Due to continuous demands from OEM's to reduce weight and make more compact vehicles, high heat generation from vehicle has become common phenomenon. Thermal insulation is a need of the hour to cater to such demands. The temperature rise is more critical around engine areas. OEM's use many design solutions to cater to such heat build up's. One of the design solutions includes use of thermally insulating materials e.g. Foams, insulating fabrics etc… First section of this paper deals with comparative study of polyurethane (PU) soft foam and rigid skin polyurethane foam. To define the base line, the samples were subjected to various tests to determine physical, thermal and chemical properties. Also both the types of foams were subjected to high temperature and low temperature heat ageing. From the experiments, it was observed that soft PU foam provides better re-bounce property than rigid skin PU foam. This is an important property to be considered, when foam is subjected to compression load during fitment. Foam would regain its shape and size on removal of load and hence provides better stability. Also, thermal conductivity of both the foams is compared to check for their ability to provide thermal insulation. Based on above results, soft PU foam was further tested for performance level tests to understand the foam behavior under simulated thermal test conditions. The thermal test method was developed to simulate heat generation during actual driving conditions. Foam was also subjected to physical test till failure including compression set. The test results are discussed and concluded for selection of better foam for the under the hood application. The results of this study were useful for determining optimum foam structure providing good insulation with lower weight.

Mehta, Shruti, Hatwalne, Mrunal, Dhule, Mangesh

A New Alloy for Medical Electronics Applications

TBMG-172839/1/2013

Although the deadline for RoHS compliance for medical device manufacturers is nearly a year away (July 22, 2014), there is more than ten years of testing and in-service data that can be used to ensure a smooth transition to lead-free medical devices and equipment.

Integral Molded Brake Pad with Long Fiber Thermosetting Molding Compound for Automotive Brake System

2012-01-18349/17/2012

Recently, in view of environment, safety, comfort and convenience for cars, the demand of low fuel consumption is increasing more than before, and weight saving of the automotive parts is pursued. In the tide of weight saving, there is a strong demand of light weightening of the backing plate by replacing steel with plastics. We have been developing long fiber phenolic molding compound, which has excellent mechanical strength and excellent heat resistance, and have examined in order to apply it to the backing plate for brake pad. By applying this material to backing plate, the weight of brake pad can be reduced in half compared with that of conventional pad made of steel. In the automotive parts, it is said that reduction of part weight under the suspension is about ten times as effective for reducing fuel consumption as that of weight upper the suspension, therefore, phenolic brake pad has a big impact. Also, instead of simple replacement of steel plate with phenolic plate, it may be possible to make integral molded brake pad with lining by using a backing plate made from the same kind of resin. Therefore, there will be no possibility of separation at the interface between backing plate and lining. Although the conventional brake pad needs a pretreatment of backing plate and adhesion with lining, all these prior process may be eliminated by integral molding technology. And phenolic backing plate does not need a coating for antirust. Cracks and blisters were not found and the flatness of molded backing plate held about 0.1 mm after thermal test at 500 deg. C. We can contribute to development of a new light weighted caliper brake system by integral molded phenolic brake pad.

Inokuchi, Hideaki

L.E.D. Signal and Marking Lighting Devices

J1889_201106 (Historical)

6/24/2011

This SAE Recommended Practice applies to functions of motor vehicle signalling and marking lighting devices which use light emitting diodes (L.E.D.’s) as light sources. This report provides test methods, requirements, and guidelines applicable to the special characteristics of L.E.D. lighting devices. This Recommended Practice is in addition to those required for devices designed with incandescent light sources. This report is intended to be a guide to standard practice and is subject to change to reflect additional experience and technical advances.

Signaling and Marking Devices Stds Comm