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.
Introduction To Structural OR Concrete Design Beams must have adequate strength against different types of failure which are: Shear more dangerous than Flexural (or Bending) failure because it creates additional tensile stresses. E.g.: Airplane wing (act as cantilever beam ) and made of Nanocomposites, composites, aluminum. Following are the types of failures in Beam: Flexural (or bending) failure Diagonal Tension failure Shear-Tension failure Shear-Compression failure Following are the types of Shear : Longitudinal Shear Transverse Shear Shear Failure Diagonal Tension Failure ↠ Shear failure of reinforced concrete beam (difficult to predict). Only valid for Homogenous beams . When we apply load on beam ↠ Bending as well as Shear stresses are produced. Shear stress have maximum value at Neutral axis N.A. Bending stress have maximum value at Extreme fibers. At maximum bending stress ↠ shear stress = 0 . Assumptions for shear stresses i...
Strain Energy or Resilence It is defined as, " energy absorbed in a body when deformation is done on material " . Depend on Material . Strain Energy Density is defined as, " strain energy per unit volume " . Independent of material . Used to tell which deformation component is greater with direction. If greater in specific direction ↔ crack propagates in that direction. Stress (in Dynamic effect) > Stress (in Static effect) Types of Loading Energy Conservation It states that, " Energy can neither be created nor be destroyed but can transfer in other forms " . We only deal with mechanical energy. External work = internal energy or strain energy . If this external force is in elastic limit, strain energy restores body back to its original undeformed position. Note: For Castigliano's Theorem ↔ See Energy Method . With the application of force on Car chassis , How it behaves? References: Material from Class Lectures + Book named Engineering Mec...
Gear Generation by Machining Tooth profile is provided by much simpler form cutting tool through hobbing, gear shaping. It involves the following methods: Gear Hobbing Gear Shaping 1. Gear Hobbing It is defined as, " a machining process in which gear teeth are progressively generated by a series of cuts with a helical cutting tool " . Most accurate machining process. Used for gears production because it has excellent surface finish. Continuous Indexing Process ↠ in which both cutting tool and workpiece rotate in constant relationship while hob is being fed into work. Feed Directions The direction of feed during hobbing operation depends upon the type of gear to be cut. Following are the types of feed directions: Axial Feeding ↠ cutting spur and helical gears (Hob axis is parallel to Blank axis). Radial Feeding ↠ for bevel gears (Hob axis is perpendicular to Blank axis). Tangential Feeding ↠ for worm, straight, spiral...
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