Perspirable Skin: A Multifuctional Material System for Self-Cooling

2008 ◽  
Author(s):  
Basak Oguz ◽  
Li Sun ◽  
Patrick Kwon
Keyword(s):  
Space Shuttle ◽  
Cooling System ◽  
Negative Thermal Expansion ◽  
Carbon Composite ◽  
Frictional Heat ◽  
Material System ◽  
Bottom Part ◽  
Element Analysis ◽  
Thermal Expansion Property ◽  
Perspirable Skin

Utilizing the negative thermal expansion property of ZrW2O8, Perspirable skin, an autonomous cooling system, was designed for externally heated surfaces of reentry vehicles such as Space Shuttle. In this material system, several ZrW2O8 pegs are shrink-fit into the Reinforced Carbon-Carbon composite (RCC) skin. At working conditions, a gap or interference forms between the two materials and the compressed gas within the vehicle can blow out through the gap. The atmospheric air, rather than contributing to the frictional heat between air and skin, is mixed with the cold compressed air over the surface. Due to the nonlinear thermoelastic properties within the operating temperatures, Finite Element Analysis was used to design the geometry of the ZrW2O8 pegs and the best fiber arrangement of the RCC for this material system. The geometry of the peg with a larger radius at the top surface and a smaller radius at the bottom part ensures the secure contact of two materials at the working condition. The design with the frustum of a cone shaped top offered a better and shorter route for the coolant gas to be passed. The best type of RCC is found to be 3D woven orthogonal.

Enhanced Negative Thermal Expansion Property Deduced by the Breaks of Superstructure

2021 ◽  
Vol 13 (4) ◽  
pp. 556-562
Author(s):  
Niu Zhang ◽  
Ming-Yi Wu ◽  
Ya-Ming Liu ◽  
Meng-Jie Yang ◽  
Ming-Ju Chao ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Expansion ◽  
Wide Temperature Range ◽  
Potential Application ◽  
Negative Thermal Expansion ◽  
Thermal Expansion Property ◽  
Expansion Property ◽  
Good Potential ◽  
Nested Structure

The HfV2O7/HfMo2O8 composite were prepared in situ. The phase, structure and thermal expansion property were analyzed. The results indicate the composite consist of cubic HfV2O7 and hexagonal HfMo2O8. The two types of structures were coexisted and mixed uniformly, and interacted with each other. The mutual nested structure suppressed the formation of 3×3×3 superstructure in HfV2O7 (RT) introduced by the reaction in situ. The promoted coupled rotation of quasi-rigid polyhedron units could enhance the negative thermal expansion (NTE) property. The HfV2O7/HfMo2O8 composite exhibits excellent NTE property from 250 to 673 K (at least) with CTE -3.09 × 10-6 K-1. The good NTE property and thermal stability over a wide temperature range, especially near the RT range, bring a good potential application in designing zero thermal expansion materials.

DESIGN AND ANALYSIS OF AN INTEGRATED THREE- BAY THERMOPLASTIC COMPOSITE WINGBOX

2021 ◽  
Author(s):  
VINCENZO OLIVERI ◽  
GIOVANNI ZUCCO ◽  
MOHAMMAD ROUHI ◽  
ENZO COSENTINO ◽  
RONAN O’HIGGINS ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Thermoplastic Composite ◽  
High Fidelity ◽  
Material System ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Single Piece ◽  
Load Carrying ◽  
Post Buckling ◽  
Composite Material System

The design of a multi-part aerospace structural component, such as a wingbox, is a challenging process because of the complexity arising from assembly and integration, and their associated limitations and considerations. In this study, a design process of a stiffeners-integrated variable stiffness three-bay wingbox is presented. The wingbox has been designed for a prescribed buckling and post-buckling performance (a prescribed real testing scenario) and made from thermoplastic composite material system (Carbon-PEEK) with the total length of three meters. The stiffeners and spars are integrated into the top and bottom panels of the wingbox resulting a single-piece blended structure with no fasteners or joints. The bottom skin also has an elliptical cut-out for access purposes. The composite tows are steered around this cutout for strain concentration reduction purposes. The fiber/tow steering in the top skin bays (compression side) has also been considered for improved compression-induced buckling load carrying capacity. The proposed design has been virtually verified via high fidelity finite element analysis.

Superalloy Cooling System for the Composite Rim of an Inside-Out Ceramic Turbine

2017 ◽  
Author(s):  
N. Courtois ◽  
F. Ebacher ◽  
P. K. Dubois ◽  
N. Kochrad ◽  
C. Landry ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Cooling System ◽  
High Strength ◽  
Carbon Composite ◽  
Flow Rate Ratio ◽  
Small Scale ◽  
Inlet Temperature ◽  
Operating Temperatures ◽  
Critical Components ◽  
Inside Out

The use of ceramics in gas turbines potentially allows for very high cycle efficiency and power density, by increasing operating temperatures. This is especially relevant for sub-megawatt gas turbines, where the integration of complex blade cooling greatly affects machine capital cost. However, ceramics are brittle and prone to fragile, catastrophic failure, making their current use limited to static and low-stress parts. Using the inside-out ceramic turbine (ICT) configuration solves this issue by converting the centrifugal blade loading to compressive stress, by using an external high-strength carbon-polymer composite rim. This paper presents a superalloy cooling system designed to protect the composite rim and allow it to withstand operating temperatures up to 1600 K. The cooling system was designed using one-dimensional (1D) models, developed to predict flow conditions as well as the temperatures of its critical components. These models were subsequently supported with computational fluid dynamics and used to conduct a power scalability study on a single stage ICT. Results suggest that the ICT configuration should achieve a turbine inlet temperature (TIT) of 1600 K with a composite rim cooling-to-main mass flow rate ratio under 5.2% for power levels above 350 kW. A proof of concept was performed by experimental validation of a small-scale 15 kW prototype, using a commercially available bismaleimide-carbon (BMI-carbon) composite rim and Inconel® 718 nickel-based alloy. The combination of numerical and experimental results show that the ICT can operate at a TIT of 1100 K without damage to the composite rim.

scholarly journals Optimisation of Coating Properties for Fibre Optic Smart Structures using Finite Element Analysis

1994 ◽  
Vol 3 (5) ◽  
pp. 096369359400300
Author(s):  
M. Hadjiprocopiou ◽  
G.T. Reed ◽  
L. Hollaway ◽  
A.M. Thorne
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Optical Fibre ◽  
Smart Material ◽  
Material System ◽  
Careful Selection ◽  
Coating Properties ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Selection Of

Finite Element analysis is used to determine and to minimise the stress concentrations which arise in a “Smart” material system due to the embedded optical fibre sensors. The FE results show that with careful selection of the coating stiffness and thickness the stress concentrations caused by the fibre inclusion in the host material can be reduced.

Computer Simulation of Filling Process and Temperature Distribution of Oil Pump Cover in Solidification Process

2013 ◽  
Vol 423-426 ◽  
pp. 1894-1897
Author(s):  
Han Wu Liu ◽  
Lian Dong Huang ◽  
Shun Qin Fan ◽  
Bo Hu
Keyword(s):  
Wall Thickness ◽  
Thermal Equilibrium ◽  
Cooling System ◽  
Die Casting ◽  
Solidification Process ◽  
Equilibrium Temperature ◽  
Forming Process ◽  
Element Analysis ◽  
Casting Mold ◽  
Oil Pump

Oil pump cover, as a part of the oil pump, is generally formed by adopting aluminum die casting molding, and required for good internal and external quality. In order to improve the oil pump cover forming quality, the paper first simulates the thermal equilibrium of die-casting mold in the forming process by finite element analysis, and obtains the temperature curves when mold works for 10 consecutive cycles, and determines that the thermal equilibrium temperature of die-casting mold is 260 °C. And then, based on the simulation results of filling and solidification in the forming process by ProCAST software, the shrinkage and cavity appear in the larger wall thickness of the casting. Meanwhile, by simulating the die-casting processes of the oil pump at different pouring temperatures, there are the least of shrinkage and cavity when the pouring temperature setting 640 °C. The results show that: it can take some methods to achieve the progressive solidification, and can reduce or eliminate the possible shrinkage and cavity, such as shortening the distance between sprue, runner and inner runner and die casting to reduce the casting heat loss, or adding cooling system to accelerate the cooling rate in the larger wall thickness of the casting. This analysis provides theoretical basis for the actual casting production of oil pump covers.

Development of a Belt Conveyor Cooling System for Concrete Aggregates

2011 ◽  
Author(s):  
Khaled I. E. Ahmed ◽  
A. M. S. Hamouda ◽  
M. S. Gadala
Keyword(s):  
Finite Element ◽  
Cooling System ◽  
Initial Conditions ◽  
Element Model ◽  
Design Parameters ◽  
Element Analysis ◽  
Conveyor System ◽  
Concrete Aggregates ◽  
Concrete Production ◽  
The Finite Element Analysis

Using hot aggregates, in concrete production, results in a drop in compressive strength of the produced concrete. Various methods have been proposed for cooling concrete aggregates. This paper proposes a new design for a conveyor system for cooling the aggregates during hot seasons. Simulation of the heat flow during the cooling process over the conveyor is analyzed with the objective of understanding the effect of the various design parameters and achieving minimum cooling time with the least possible power. A finite element model for the new design is proposed and discussed. Challenges facing numerical simulation are addressed in this paper. The results of the finite element analysis of the new design are presented for various initial conditions and cooling rates.

A STUDY ON THE FAILURE ANALYSIS OF CAST IRON BRAKE BLOCKS THAT ARE USED FOR RAILWAY APPLICATIONS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4535-4540
Author(s):  
CHANG-MIN SUH ◽  
BYUNG-WON HWANG ◽  
WOO-HO BAE
Keyword(s):  
Cast Iron ◽  
Hot Spots ◽  
Hot Spot ◽  
Frictional Heat ◽  
Failure Behavior ◽  
Surface Cracks ◽  
Element Analysis ◽  
Actual Application ◽  
The Matrix ◽  
Brake Block

In order to clarify the cracking and failure behavior of gray cast iron brake blocks that are used for the railway applications, macro- and micro observations regarding the cracks and the micro-structure of the used brake blocks were examined. Three brake blocks, which have different degrees of hot spots and cracking during the actual application, were selected for testing. In addition, a thermal-mechanical coupled finite element analysis (FEA) was applied to calculate the temperature and the stress field in the brake blocks during braking. As a result, it was observed that surface cracks were initiated at the hot spots and propagated into the matrix. From the observation of dispersed graphites close to the crack path, it can be said that the deterioration of materials due to the frictional heat of braking made it easy to initiate cracks at the hot spot. The hardness of the brake block was recommended to be under 85 by the Rockwell B scale in order to prevent hot spots and crack initiation. From the FEA, the procedure for the occurrence of hot spots and cracks was successfully simulated by assuming the surface roughness on the slid surface of the brake block.

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