View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge. Photoshoped pics are developed. Some pics and GIF from Google. Videos from YouTube ( Engineering Sights ).
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Advance High Strength Steel (AHSS)
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Advance High Strength Steel
Conventional low carbon mild steel has simpler ferritic structure (α-iron) and good ductility.
Common type of HSS is High Strength Low Alloy (HSLA) ⇥ has yield strength 550 - 690 N/sq.mm.
Manganese ⇥ supporter (stabilizer) of ferrite.
Conventional HSS:
Is single-phase ferritic steel with a potential for some pearlite in C-Mn steel.
Lower strain hardening capacity.
Advance HSS:
primarily steel with a microstructure containing a phase other than ferrite, pearlite, cementite.
Crumple Zone ⇥ Made with those materials which absorb maximum amount of energy.
Safety Cage ⇥ Multiple areas (like cabins, structural elements).
Areas of Safety cage are described ahead:
Cabins (Blue Areas) ⇥ Should have high strength with a good balance of strength, formability, energy absorption and durability.
Structural Elements (Red Areas) ⇥ Safety critical parts.
Conclusion is:
Dual phase (DP) & Transformation induced plasticity (TRIP) steels are excellent in crash zone (high energy absorption capacity), so it is used to make Crumple Zone.
For structural elements ⇥ Extremely high strength steels such as Martensite and Boron-based Press Hardened (PHS) steels are used.
Advance HSS Family
Dual Phase (DP)
Complex Phase (CP)
Ferritic Bainitic (FB)
Martensite
Transformation Induced Plasticity (TRIP)
Hot Formed (HF)
Twinning Induced Plasticity (TWIP)
Dual Phase (DP) Steel
It consist of a ferritic matrix containing a hard martensite second phase in the form of island.
Microstructure is produced by giving steel a Sub-Critical Anneal at 800℃ and is quenched to room temperature.
Sub-Critical Anneal ⇥ Heating a material (steel) lower than the equilibrium line between austenite and α-phase and then cool it.
Ferrite is unaffected by heat treatment but Austenite grains transformed to martensite during quenching and is tempered at low temperature to increase ductility.
Tempering ⇥ heat treatment process that is performed in steels containing martensite just to relief some stresses.
DP Steel exhibits high work hardening rate, ultimate tensile strength, Tensile & Yield strength ratio.
Transformation Induced Plasticity (TRIP) Steel
It consist of Austenite embedded in a primary matrix of ferrite.
To get retained austenite ⇥ use Step Quenching (from Transformation Time VS Transformation Temperature Graph)
TRIP steel has lower initial work hardening rate than DP.
It uses higher quantities of carbon than DP to obtain sufficient carbon content for stabilizing the retained austenite phase to below ambient temperature.
Si & Al ⇥ used to avoid carbide precipitation in the bainite region.
Projection: The term Projection is defined as: Presentation of an image or an object on a surface. The principles used to graphically represent 3-D objects and structures on 2-D media and it based on two variables: Line of Sight. Plane of Projection. Line of Sight & Plane of Projection: Line of sight is divided into 2 types: Parallel Projection Converging Projection & A plane of projection is an imaginary flat plane upon which the image created by the lines of sight is projected. Orthographic Projection: When the projectors are parallel to each other and perpendicular to the plane of projection. The lines pf sight of the observer create a view on the screen. The screen is referred to as the Plane of Projection (POP). The lines of sight are called Projection lines or projectors. Rules of Orthographic Projection: Edges that are parallel to a plane of projection appear as lines. Edges that are incl...
Gear Forming by Machining Formation of gear through machining consists of following methods: Form Milling by Disc Cutter Form Milling by End Mill Cutter Shaper, Planner and Slotter Broaching 1. Form Milling by Disc Cutter It is defined as, " Tooth is cut one by one by plunging the rotating cutter into the blank " . Each gear needs a separate cutter. 8 - 10 standard cutters are available for producing 12 - 120 teeth gears. Used for big spur gears of large pitch. 2. Form Milling by End Mill Cutter It includes the cutting of tooth at a time and then indexed for the next tooth space for cutting. For a small volume production of low precision gears. Set of 10 cutters ↠ 12 - 120 teeth gears . Used for teeth of large gears/module. To reduce cost, same cutter is often used for multiple sized gears resulting in profile errors . Characteristics: Use of Hardened stainless steels (HSS) form milling cutters. Use of Ordinary milling machines. Low production rate (need of indexing...
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