This document discusses aircraft materials, focusing on aluminum alloys. It provides an overview of the basic requirements for aircraft materials, including high strength, stiffness, corrosion resistance, and fatigue resistance. Common structural materials are aluminum, magnesium, titanium, and composite materials. Important aluminum alloys for aircraft include the 2xxx, 6xxx, and 7xxx series. Properties of specific alloys like 2024, 6061, 7075 are presented. Casting aluminum alloys and their microstructure and properties are also reviewed.
Surface hybrid nanocomposites via friction stir processingmohammed noor
Friction stir Processing (FSP) is a new innovative technology developed based on the principle of Friction Stir Welding (FSW) technique.
In FSP, the ceramic particulates are reinforced into the base metal by adding it into the groove and Friction Stir Processing (FSP) is performed.
In this study, the aluminum alloy 6061 is chosen as the base metal, alumina and graphite Nano powder as reinforcement.
The process parameters such traverse speed of 64 mm/min and the tool rotational speed of 1060 rpm and tilt angle of 2deg were selected, The Friction Powder Processing was carried out on vertical milling machine.
New parameters such as powder type and number of passes were involved and we also study the effect of heat treatment.
The influence of FSP was checked using some tests such as the microstructure analysis that was carried out using optical microscope (OM) and the mechanical characteristics were analyzed using tensile test and hardness test.
The micrograph results revealed that powder particulates were evenly distributed in the stir zone and reduction in grain size also observed; the reason for the grain size reduction was stirring action of the FPP tool’s pin.
The tensile strength results showed a significant improvement in strength by a percent of
50% compared to base metal but when T6 heat treatment is applied, the tensile strength decreased.
Using Steel In Solar Racking and MountingJMCSteelGroup
When it comes to solar installations, steel provides a number of advantages that you may not already know. Steel supplier Wheatland Tube and racking manufacturer Patriot Solar Group detail the latest in steel-working knowledge and how best to apply the metal in solar racking and mounting.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
Surface hybrid nanocomposites via friction stir processingmohammed noor
Friction stir Processing (FSP) is a new innovative technology developed based on the principle of Friction Stir Welding (FSW) technique.
In FSP, the ceramic particulates are reinforced into the base metal by adding it into the groove and Friction Stir Processing (FSP) is performed.
In this study, the aluminum alloy 6061 is chosen as the base metal, alumina and graphite Nano powder as reinforcement.
The process parameters such traverse speed of 64 mm/min and the tool rotational speed of 1060 rpm and tilt angle of 2deg were selected, The Friction Powder Processing was carried out on vertical milling machine.
New parameters such as powder type and number of passes were involved and we also study the effect of heat treatment.
The influence of FSP was checked using some tests such as the microstructure analysis that was carried out using optical microscope (OM) and the mechanical characteristics were analyzed using tensile test and hardness test.
The micrograph results revealed that powder particulates were evenly distributed in the stir zone and reduction in grain size also observed; the reason for the grain size reduction was stirring action of the FPP tool’s pin.
The tensile strength results showed a significant improvement in strength by a percent of
50% compared to base metal but when T6 heat treatment is applied, the tensile strength decreased.
Using Steel In Solar Racking and MountingJMCSteelGroup
When it comes to solar installations, steel provides a number of advantages that you may not already know. Steel supplier Wheatland Tube and racking manufacturer Patriot Solar Group detail the latest in steel-working knowledge and how best to apply the metal in solar racking and mounting.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
An Approach to Detecting Writing Styles Based on Clustering Techniquesambekarshweta25
An Approach to Detecting Writing Styles Based on Clustering Techniques
Authors:
-Devkinandan Jagtap
-Shweta Ambekar
-Harshit Singh
-Nakul Sharma (Assistant Professor)
Institution:
VIIT Pune, India
Abstract:
This paper proposes a system to differentiate between human-generated and AI-generated texts using stylometric analysis. The system analyzes text files and classifies writing styles by employing various clustering algorithms, such as k-means, k-means++, hierarchical, and DBSCAN. The effectiveness of these algorithms is measured using silhouette scores. The system successfully identifies distinct writing styles within documents, demonstrating its potential for plagiarism detection.
Introduction:
Stylometry, the study of linguistic and structural features in texts, is used for tasks like plagiarism detection, genre separation, and author verification. This paper leverages stylometric analysis to identify different writing styles and improve plagiarism detection methods.
Methodology:
The system includes data collection, preprocessing, feature extraction, dimensional reduction, machine learning models for clustering, and performance comparison using silhouette scores. Feature extraction focuses on lexical features, vocabulary richness, and readability scores. The study uses a small dataset of texts from various authors and employs algorithms like k-means, k-means++, hierarchical clustering, and DBSCAN for clustering.
Results:
Experiments show that the system effectively identifies writing styles, with silhouette scores indicating reasonable to strong clustering when k=2. As the number of clusters increases, the silhouette scores decrease, indicating a drop in accuracy. K-means and k-means++ perform similarly, while hierarchical clustering is less optimized.
Conclusion and Future Work:
The system works well for distinguishing writing styles with two clusters but becomes less accurate as the number of clusters increases. Future research could focus on adding more parameters and optimizing the methodology to improve accuracy with higher cluster values. This system can enhance existing plagiarism detection tools, especially in academic settings.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
2. AIRCRAFT MATERIALS
1. Basic requirements
• High strength and stiffness
• Low density
=> high specific properties e.g. strength/density, yield strength/density,
E/density
• High corrossion resistance
• Fatigue resistance and damage tolerance
• Good technology properties (formability, machinability, weldability)
• Special aerospace standards and specifications
2. Basic aircraft materials for airframe structures
• Aluminium alloys
• Magnesium alloys
• Titanium alloys
• Composite materials
3. Development of aircraft materials for airframe structures
composites
Mg alloys
other Al alloys
pure AlZnMgCu
alloys
pure AlCuMg
alloys
new Al
alloys
steel
Year
AlCuMg alloys
wood
other materials
Relative share
of structural
materials Ti alloys
10. Aluminium – Al
• plane centered cubic lattice
• melting point 660 °C
• density 2.7 g/cm³
• very good electrical and heat conductivity
• very good corrosion resistance
• low mechanical properties
• solid solutions with alloying elements
• maximum solubility is temperature dependent
– Cu: 6 % at 548 °C; 0.1 % at RT
– Mg: 17 % at 449 °C; 1.9 % at RT
– Zn: 37 % at 300 °C; 2 % at RT
– Si: 1.95 % at 577 °C; 0 % at RT
Substitution solid solution
a) alloying atom > aluminium atom
b) pure aluminium
c) alloying atom < aluminium atom
11. Characteristics of aluminium alloys
Advantages
• Low density 2.47- 2.89 g/cm³
• Good specific properties – Rm/ρ, E/ ρ
• Generally very good corrosion
resistance (exception alloys with
Cu)
• Mostly good weldability – mainly
using pressure methods
• Good machinability
• Good formability
• Great range of semifinished
products
(sheet, rods, tubes etc.)
• Long-lasting experience
• Acceptable price
Shortcomings
• Low hardness, susceptibility to
surface damage
• High strength alloys (containing Cu)
need additional anti-corrosion
protection:
– Cladding – surface protection using
a thin layer of pure aluminium or
alloy with the good corrosion
resistance
– Anodizing – forming of surface oxide
layer (Al2O3)
• It is difficult to weld high strength
alloys by fusion welding
• Danger of electrochemical corrosion
due to contact with metals:
– Al-Cu, Al-Ni alloys, Al-Mg alloys, Al-
steel
12. Designation of aluminium alloys according to EN
Wrought alloys
AL-PXXXX(A)
designation basic alloying element
• 1XXX – pure aluminium
• 2XXX - copper (Cu)
• 3XXX - manganese (Mn)
• 4XXX - silicon (Si)
• 5XXX - magnesium (Mg)
• 6XXX - Mg + Si
• 7XXX - zinc (Zn)
• 8XXX - other (eg. Li)
Casting alloys
AL-CXXXXX
designation basic alloying element
• 1XXXX - > 99.0 % Al
• 2XXXX - Cu
• 3XXXX - Si-Mg
- Si-Cu
- Si-Cu-Mg
• 4XXXX - Si
• 5XXXX - Mg
• 7XXXX - Zn
• 8XXXX - Sn
25. Casting aluminum alloys
• Designation (in addition to EN)
– Often used system (Aluminum Association - USA): three digit designation
- the first digit indicates a main alloying element
• 1XX 99,0 % Al
• 2XX Al - Cu
• 3XX Al - Si - Mg
Al - Si - Cu
Al - Si - Cu - Mg
• 4XX Al - Si
• 5XX Al – Mg
• 7XX Al - Zn
• 8XX Al – Sn
A letter ahead of designation marks alloys with the same content of main
alloying elements but with different content of impurities or micro alloying
elements.(e.g. 201 - A201, 356 - A356, 357 - A357)
Additional digit .0 means shape casting, digit .1 or .2 ingots
26. • Typical castings in aircraft structures
Al – front body of engine
32 kg - D=700 mm
Al- steering part - 1,1 kg
390 x 180 x 100 mm
Al – pedal - 0,4 kg
180 x 150 x 100 mm
Al – casing - 1,3 kg
470 x 190 x 170 mm
27. • General characteristics
– Micro and macro structures of metal are influenced by conditions of metal
solidification – quantity of nuclei, temperature interval of solidification,
cooling rate …
A fine, equiaxed grain structure is normally desired in aluminum
casting (Al-Ti or Al-Ti-B alloys are most widely used grain refiners)
– Mechanical properties are influenced by existence of casting defects –
porosity, inclusions (mainly oxides), shrinkage voids ….
– Alloys – heat treatable , non heat treatable
– Mechanical properties are mostly lower comparing wrought alloys of the
similar chemical composition
– High quality aircraft casting need careful metallurgical processing of liquid
metal
• Degassing – hydrogen elimination (hydrogen causes porosity)
• Grain refinement and modification for better mechanical properties
• Filtration for inclusions removing
28. Alloy Al-7Si – the effect
of grain refinement
Solubility of hydrogen in
aluminum
During solidification - dissolved
hydrogen can precipitate and form
voids.
29. Dendritic microstructure of hypoeutectic alloy
AlSi10Mg – sand casting
wall thickness 2 mm wall thickness 10 mm
There is direct relation between mechanical properties and dendrite
arm spacing (DAS) → different properties in different portions of
casting
30. • Alloys of Al–Cu system
- Composition 4 – 6 % Cu
- Copper substantially improves strength and hardness in the as-cast and
heat- treated conditions
- Copper generally reduces corrosion resistance and, in specific compositions
stress corrosion susceptibility
- Copper also reduces hot tear resistance and decreases castability
- Main advantage: high strength up to 300 °C
- Basic alloys
• ČSN 424351, 201, A 201, AL 7
• 242, A242
• B295
- Application:
Smaller , simple, high-strength castings for service at higher
temperatures (cylinder heads, pistons, pumps, aerospace housings, aircraft
fittings)
31. • Alloys of Al–Si + (Mg, Cu, Ni) system
– The most important alloys for aircraft castings
– Silicon improves casting characteristics (fluidity, hot tear resistance, feeding),
Si content depends on casting methods
• Sand and plaster molds, investment casting 5-7% Si
• Permanent molds 7-9% Si
• Die casting 8-12% Si
– Alloys containing Mg are heat treatable, hardening phase is Mg2Si
– Alloys Al-Si with alloying elements Mg and Cu have after heat treatment high
mechanical properties but lower plasticity and corrosion resistance
– Ni is alloying element in hypereutectic alloys for service at higher temperatures (e.g.
engine pistons)
– Strength and ductility can be improved using modification for refinement of eutectic
phases
• Principal – addition small quantities of Na or Sr into liquid metal before casting
• Results – increased tensile strength (40 %), impact strength (up to 400 %), ductility (2x)
– Mechanical properties can be improved also due to grain refinement buy rapid cooling
in permanent metal molds
32. Representative aluminum alloys – sand casting
Alloy Temper
Mechanical properties
Rm
MPa
Rp0,2
MPa
HB A
%
A 201.0
AlCu4,5Ag0,7Mg0,25Mn0,3
T7 496 448 - 6
A 356.0
AlSi7Mg0,35
F
T6
T61*
159
278
283
83
207
207
-
75
90
6
6
10
A 357.0
AlSi7Mg0,55ZnBe0,05
T6
T6*
317
359
248
290
85
100
3
5
* permanent mold casting
F as cast
.0 shape casting
34. General characteristics of Mg alloys
• Pure magnesium
– Hexagonal crystal lattice
– ρ=1,74 g/cm³ , Rm=190 MPa, Rp0,2=95 MPa
– Used in metallurgy (alloying element in Al alloys, titanium metallurgy, ductile iron
metallurgy).
– Not used for structural purposes – magnesium alloys have better utility values
• Advantages of Mg alloys
– Low density (ρ = 1,76–1,99 g/cm³ ) → high specific strength (Rm/ ρ)
– Comparing Al alloys, lower rate of strength decrease in relation with temperature
– Lower notch sensitivity and higher specific strength at vibrating loads
– High damping capacity (influence of low modulus of elasticity ~47GPa)
– High specific bending stiffness (higher to 50 % comparing steel, to 20 % comparing Al)
→ high resistance against buckling
– High specific heat → minor temperature increasing at short time heating
– Very good machinability
– Applicability – most alloys up to 150 °C, some of them up to 350 °C.
35. • Shortcomings of Mg alloys
– High reactivity at increased temperatures
• Above 450 °C rapid oxidation, above 620 °C ignition (fine chips, powder)
• Melting and casting – protection against oxidation (chlorides, fluorides, oxides Mg,
powder sulfur, gases SO2, CO2).
– Lower corrosion resistance , generally difficult anti-corrosion protection
• Corrosion environment (air, sea water), impurities Fe, Cu, Ni forming intermetallic
compounds
• Electrochemical corrosion – in contact with the most of metals (Al alloys, Cu alloys, Ni
alloys, steel)
– Low formability at room temperature - most alloys cannot be formed without heating
– After forming – high strength anisotropy along and crosswise deformation –→
differences 20 to 30 %.
– Low shear strength and notch impact strength
– Low wear resistance
– Low diffusion rate during heat treatment → longtime processes , artificial aging is
necessary at precipitation hardening
– Relatively difficult joining – possible electrochemical corrosion, limited weldability
(hot cracking, weld porosity, possible welding techniques - inert gas welding, spot
welding)
36. • Designation according to EN 2032-1
– Wrought alloys MG-PXXXXX
– Casting alloys MG-CXXXXX
– In numerical designation, one or two digits represent one or two main alloying
elements according to their weight percentage. The third digit is zero, the last
two digits represent serial number.
(1- Al, 2 – Si, 3 – Zr, 4 – Ag, 5 – Th, 6 – rare earth, 7 – Y, 8 – Zn, 9 - other)
• More common designation - according to ASM:
– Series AZ (alloying elements Al, Zn)
– Series AM (Al, Mn)
– Series QE (Ag, RE - rare earth )
– Series ZK (Zn, Zr)
– Series AE (Al, RE)
– Series WE (Y, RE)
– Series HM, HZ, HK (Th, Mn, Zn, Zr) – high temperature alloys
– Two first digits – percentage of alloying elements
Designation of Mg alloys
37. Basic wrought Mg alloys
• Mg-Al-Zn (AZ)alloys
– The most common alloys in aircraft industry, applicable up to 150 °C
– Composition – 3 to 9 % Al, 0.2 to 1.5 % Zn, 0.15 to 0.5 % Mn
– Increasing Al content → strength improvement , but growth of susceptibility
to stress corrosion
– Zn → ductility improvement
– (Cd + Ag) as Zn replacement → high strength up to 430 MPa
– Precipitation hardening → strength improvement + decrease of ductility
– The most common alloy for sheet and plates – AZ31B (applicable to 100 °C)
Alloy Composition Semi-product Rm, MPa Rp0.2, MPa Ductility,%
AZ31B-F 3.0Al-1.0Zn bars, shapes 260 200 15
AZ61A-F 6.5Al-1.0Zn bars, shapes 310 230 16
AZ80A-T5 8.5Al-0.5Zn bars, shapes 380 240 7
AZ82A-T5 8.5Al-0.5Zn bars, shapes 380 275 7
AZ31B-H24 3.0Al-1.0Zn sheet, plates 290 220 15
38. • Mg-Zn-Zr alloys (ZK)
– Zn → strength improvement
– Zr → fine grain → improvement of strength, formability and corrosion resistance
– Better plasticity after heat treatment
– Alloying with RE a Cd → tensile strength up to 390 MPa
– Application up to 150 °C
• Mg-Mn alloys (M)
– Good corrosion resistance, hot formability, weldability
– Not hardenable → lower strength
Alloy Composition Semi-product Rm, MPa Rp0.2, MPa Ductility, %
ZK60A-T5 5.5Zn-0.45Zr bars, shapes 365 305 11
M1A-F 1.2Mn bars, shapes 255 180 12
39. • Mg-Th-Zr (HK)
– High temperature alloys
– Example: alloy HK31A - service temperature 315 to 345 °C
• Mg-Th-Mn (HM)
– Medium strength
– Creep resistance → service temperature up to 400 °C
• Mg-Y-RE (WE)
– Hardenability, formability, good weldability
– Y → strength after hardening, Nd → heat resistance, Zr → grain refinement
– Application to 250 °C
alloy composition semi-product Rm, MPa Rp0.2, MPa ductility, %
HM21A-T8 2.0Th-0.6Mn sheet, plates 235 130 11
HK31A-H24 3.0Th-0.6Zr sheet, plates 255 160 9
Mg-RE (WE) 8.4Y-0.5Mn-
0.1Ce-0.35Cd
bars, shapes 410 360 4
40. Cast magnesium alloys
• Basic systems
– Mg-Al-Mn with or without Zn (AM, AZ)
– Mg-Ag-RE (QE)
– Mg-Y-RE (WE)
– Mg-Zn-Zr with or without rare earth (ZK, ZE, EZ)
• Pressure die castings
- alloys AZ → excellent castability, good corrosion resistance in sea water
- aloys AM → good castability, corrosion resistance, better ductility and lower
strength
- castings are not heat treated
• Sand and permanent mold castings
- used mostly in heat treated state
43. Characteristics of titanium and titanium alloys
• Pure titanium - 2 modifications
– αTi – to 882 °C, hexagonal lattice
– βTi – 882 to 1668°C, cubic body centered lattice
– With alloying elements, titanium forms substitution solid solutions α and β
• Commercially pure titanium can be used as structural material in many applications,
but Ti alloys have better performance.
• Basic advantages of Ti
– Lower density comparing steel ( ρ = 4.55 g/cm³)
– High specific strength at temperatures 250 – 500 °C, when alloys Al, Mg already cannot
be used
– High strength also at temperatures deep below freezing point
– Good fatigue resistance (if the surface is smooth, without grooves or notches)
– Excellent corrosion resistance due to stabile layer of Ti oxide
– Good cold formability, some alloys show superplasticity
– Low thermal expansion => low thermal stresses
44. • Shortages of titanium
– High manufacturing costs => high prices (~8x higher comparing Al)
– Chemical reactivity above 500 °C – intensive reactions with O2, H2, N2, with refractory
materials of furnaces and foundry molds => brittle layers, which are removed with
difficulties
– Lower modulus of elasticity comparing steel ( E = 115 GPa against 210 GPa)
– Poor friction properties, tendency for seizing
– Poor machinability (low thermal conductivity → local overheating, adhering on tool,
above 1200 °C danger of chips and powder ignition.
– Welding problems (reactivity with atmospheric gases => welding in inert gas, diffusion
welding, laser beam welding, electron beam welding)
– Special manufacturing methods (vacuum melting and heat treating, manufacture of
castings in special molds – graphite molds and/or ceramic molds with a layer of carbon,
hot isostatic pressing - HIP)
• Preferred use of titanium alloys
– If strength and temperature requirements are too high for Al or Mg alloys
– At conditions, when high corrosion resistance is required
– At conditions, when high yield strength and lower density comparing steel are required
– Compressor discs, vanes and blades, beams, flanges, webs, landing gears, pressure
vessels, skin up to 3M, tubing…
– Increasing usage (Boeing 727 – 295 kg, Boeing 747 – 3400 kg)
45. Classification of titanium alloys
• Alloying elements
– α – stabilizers (Al, O, N, C) – stabilize solid solution α and enlarge zone of its existence
– β – stabilizers – stabilize solid solution β, decrease temperature α-β transformation
• β stabilizers forming eutectoid phase (Si, Cr, Mn, Fe, Co, Ni, Cu)
• β stabilizers isomorphic (V, Mo, Nb, Ta)
– Neutral elements (Sn, Zr) – only small influence on the α-β transformation
Phase diagrams of Ti with different stabilizers (solid
state)
46. • Classification of alloys according to microstructure after annealing
– α alloys – microstructure consists of homogeneous solid solution α
– pseudo α alloys (solid solution α + 5% solid solution β at most)
– α+β alloys – microstructure consists of mixture solid solutions α and β
– β alloys – microstructure consists of homogeneous solid solution β
– pseudo β alloys (solid solution β + small amount solid solution α)
– Alloys consisting of intermetallic compouds
• Classification according to usage
– Wrought alloys
– Cast alloys
• Designation of titanium alloys according to EN 2032-1
• Wrought material TI-PXXXXX
• Cast material TI-CXXXXX
• Product of powder metallurgy TI-RXXXXX
• First two digits represent main alloying elements (1-Cu, 2-Sn, 3-Mo, 4-V, 5-Zr, 6-Al,
7-Ni, 8-Cr, 9-others), TI-P64005 (Ti-6Al-4V), TI-P99XXX (pure titanium)
• Designation according to basic chemical composition (e.g. Ti-6Al-4V)
48. Cast titanium alloys
• Comparison with wrought alloys
– Similar chemical composition
– Higher content of impurities, specific casting structure and defects (e.g. porosity)
– Lower ductility and fatigue life
– Often better fracture toughness
• Manufacture of shape castings
– Good casting properties (fluidity, mold filling)
– Hydrogen absorption, porosity
– Vacuum melting, special molds, hot izostatic pressing of castings (HIP)
• HIP – heating close to solidus + pressure of inert gas (elimination and welding of voids due to
plastic deformation) – conditions 910 to 965 °C/100 MPa/2 h.
Alloy Heat Treatment Rm, MPa Rp0.2, MPa A5 , %
Ti-6Al-4V stress relief annealing 880 815 5
Ti-6Al-2Sn-4Zr-2Mo 970°C/2h + 590°C/8h 860 760 4
Ti-15V-3Cr-3Al-Sn 955°C/1h + 525°C/12h 1120 1050 6
Examples of cast alloys
50. Most composites consist of a bulk material (the ‘matrix’), and a
reinforcement, added primarily to increase the strength and stiffness of the
matrix. This reinforcement is usually in fibre form.
Today, the most common man-made composites can be divided into three main
groups:
Polymer Matrix Composites (PMC’s) – These are the most common and will
be discussed here. Also known as FRP - Fibre Reinforced Polymers (or Plastics)
– these materials use a polymer-based resin as the matrix, and a variety of fibres
such as glass, carbon and aramid as the reinforcement.
Metal Matrix Composites (MMC’s) - Increasingly found in the automotive industry,
these materials use a metal such as aluminium as the matrix, and reinforce it with fibres
such as silicon carbide (SiC).
Ceramic Matrix Composites (CMC’s) - Used in very high temperature
environments, these materials use a ceramic as the matrix and reinforce it with short fibres,
or whiskers such as those made from silicon carbide and boron nitride (BN).
51. Polymer fibre reinforced composites
Common fiber reinforced composites are composed of
fibers and a matrix.
Fibers are the reinforcement and the main source of strength
while the matrix 'glues' all the fibres together in shape
and transfers stresses between the reinforcing fibres.
Sometimes, fillers or modifiers might be added
to smooth manufacturing process, impart special properties,
and/or reduce product cost.
52. Polymer matrix composites
• The properties of the composite are determined by:
- The properties of the fibre
- The properties of the resin
- The ratio of fibre to resin in the composite (Fibre Volume Fraction)
- The geometry and orientation of the fibres in the composite
Properties of unidirectional
composite material
53. Main resin systems
• Epoxy Resins
The large family of epoxy resins represent some of the highest performance resins of those
available at this time. Epoxies generally out-perform most other resin types in terms of
mechanical properties and resistance to environmental degradation, which leads to their
almost exclusive use in aircraft components
• Phenolics
Primarily used where high fire-resistance is required, phenolics also retain their properties
well at elevated temperatures.
• Bismaleimides (BMI)
Primarily used in aircraft composites where operation at higher temperatures (230 °C
wet/250 °C dry) is required. e.g. engine inlets, high speed aircraft flight surfaces.
• Polyimides
Used where operation at higher temperatures than bismaleimides can stand is required (use
up to 250 °C wet/300 °C dry). Typical applications include missile and aero-engine
components. Extremely expensive resin.
54.
55. Fabric types and constructions
• Unidirectional fabrics
– The majority of fibres run in one direction only, a small amount of fibre may run in
other directions to hold the primary fibres in position
– Prepreg unidirectional tape- only the resin system holds the fibres in place
– The best mechanical properties in the direction of fibres
• Basic woven fabrics
– Plain -Each warp fibre passes alternately under
and over each weft fibre. The fabric is
symmetrical, with good stability. However,
it is the most difficult of the weaves to drape.
– Twill - One or more warp fibres alternately weave
over and under two or more weft fibres in a regular
repeated manner. Superior wet out and drape,
smoother surface and slightly higher mechanical
properties
56. Fabric types and constructions – cont.
– Basket -Basket weave is fundamentally the same
as plain weave except that two or more warp fibres
alternately interlace with two or more weft fibres.
An arrangement of two warps crossing two wefts
is designated 2x2 basket.It is possible to have 8x2,
5x4, etc. Basket weave is flatter, and, through
less crimp, stronger than a plain weave, but less stable.
• Hybrid fabric
– A hybrid fabric will allow the two fibres to be presented in just one layer of fabric.
– Carbon / Aramid - The high impact resistance and tensile strength of the aramid
fibre combines with high the compressive and tensile strength of carbon.
– Aramid / Glass - The low density, high impact resistance and tensile strength of
aramid fibre combines with the good compressive and tensile strength of glass,
coupled with its lower cost.
– Carbon / Glass - Carbon fibre contributes high tensile compressive strength and
stiffness and reduces the density, while glass reduces the cost.
57.
58. Properties of composites
• UD laminate
Properties directionally
dependent
• Quasi-isotropic laminate
Properties nearly equal in all
directions
Tensile
strength,
MPa
Angle between fibers and stress, °
59. Properties of epoxy UD prepreg laminates
Fibre fracture volume typical for aircraft structures
Prepreg
Fabrics and fibres are pre-impregnated by the materials manufacturer with a pre-catalysed
resin. The catalyst is largely latent at ambient temperatures giving the materials several
weeks, or sometimes months, of useful life. To prolong storage life the materials are stored
frozen (e.g. -20°C). High fibre contents can be achieved, resulting in high mechanical
properties.
60.
61. Fiber metal laminates
• Consist of
alternating thin
metal layers and
uniaxial or biaxial
glass, aramid or
carbon fiber
prepregs
62. Fibre metal laminates
• Developed types
- ARALL - Aramid Reinforced ALuminium Laminates (TU-DELFT)
- GLARE - GLAss REinforced (TU-DELFT)
- CARE - CArbon REinforced (TU-DELFT)
- Titanium CARE (TU-DELFT)
- HTCL - Hybrid Titanium Composite Laminates (NASA)
- CAREST – CArbon REinforced Steel (BUT - IAE)
- - T iGr – Titanium Graphite Hybrid Laminate (The Boeing Company)
• Advantages
Fibre metal laminates produce remarkable improvements in fatigue
resistance and damage tolerance characteristics due to bridging
influence of fibres. They also offer weight and cost reduction and
improved safety, e.g. flame resistance. They can be formed to limited
grade.
67. Fiber metal laminates - application
AIRBUS A 380
Panels of fuselage upper part – 470 m² , GLARE 4
Maximum panel dimensions 10.5 x 3.5 m
Weight saving - 620 kg
Adhesive bonded stringers from 7349 alloy
68. Sandwich materials
• Structure – consists of a lightweight core
material covered by face sheets on both
sides. Although these structures have a
low weight, they have high flexural
stiffness and high strength.
• Skin (face sheet)
– Metal (aluminium alloy)
– Composite material
• Core
– Honeycomb – metal or composite
(Nomex)
– Foam – polyurethan, phenolic,
cyanate resins, PVC
• Applications – aircraft flooring,
interiors, naccelles, winglets etc.
Sidewall panel for Airbus A320
70. List of problems (light alloys)
What are the main advantages of aluminium alloys for applications in aircraft structures?
What numerical designation system is used for identification of wrought aluminium alloy?
What is meaning of the first digit?
What groups of wrought aluminium alloys are usually used in aircraft structures?
Explain the designation of the following alloys:
- 2024 T4
- 7075 T6
- Alclad 2219
Why is sheet from 2xxx alloys often clad with pure aluminium?
What group of wrought aluminium alloys exhibits the best mechanical properties?
Compare alloys 6056 and 7050!
What are the main advantages and limitations of Al-Li alloys comparing to other Al alloys?
What is a common value of aluminium alloys elastic modulus in tension?
Recommend the alloys for aircraft skin!
Why are Mg alloys valuable for aerospace application?
What is damping capacity of magnesium alloys?
What are the main reasons for using of titanium alloys in airframe and engine structures?
What titanium alloy is the most widely used?
Compare the specific tensile strength and specific tensile modulus of 2090 and Ti-6Al-4V
alloys!
- (Specific value = value/density)
71. List of problems (composite and sandwich materials)
What is composite material?
What are advantages of composites comparing to metals?
What is prepreg?
What are common types of fibres?
What fibres have the highest specific tensile strength and specific tensile modulus?
( the specific property is the ratio value/density )
What is main role of matrix?
What are main advantages of epoxy, phenolic and bismaleimide (polyimide) matrices?
What are main advantages of using prepregs?
How the fibre orientation influences resulting mechanical properties of a composite?
What are typical tensile properties of epoxy prepregs UD laminates along and across fibres?
What is structure of sandwich material?
What are main advantages of sandwich panels compared to solid panels?
What materials are usually used for sandwich skins and core?