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 ).
Get link
Facebook
X
Pinterest
Email
Other Apps
Crystal Structures
Get link
Facebook
X
Pinterest
Email
Other Apps
-
Crystalline Solids and it's Structures
Crystalline Solids are defined as, "atoms arranged in periodic manner over long atomic distances in 3D patterns".
It deals with the unit cell (smallest part of structure).
If no 3D pattern ⇔ non-crystalline or amorphous solids.
Single Crystal ⇔ all unit cells interlock in the same way in the same orientation.
Polycrystalline Material ⇔ collection of small crystals (or grains) having random crystallographic orientation.
There are two types of unit cells, namely
Hard-Sphere unit cell
Reduced-Sphere unit cell
Types of Crystal Structures
Following are the types of crystal structures:
1. Face-Centered Cubic (FCC) Crystal Structure
It is defined as, "Unit cell of cubic geometry in which atoms are located at each of corners and centers of all cubic faces".
Each corner atom is shared among 8 unit cells.
Face-centered atom shared with 2 unit cells.
2. Body-Centered Cubic (BCC) Crystal Structure
It is defined as, "Cubic unit cell with atoms located at all eight corners and single atom at cubic center".
Center and corner atoms touch one another along cube diagonals.
Coordination number of BCC is 8.
3. Hexagonal Close-Packed (HCP) Crystal Structure
It is defined as, "Unit cell having cubic structure and have top and bottom faces consist of 6 atoms that forms regular hexagon and surround a single atom in the center".
Three additional atoms ⇔ provided to a plane between top and bottom face.
Coordination number is 12.
Atomic Packing factor is 0.74.
Stacking Sequence
It is defined as, "conversion of 2D layers to 3D structures to minimize empty spaces".
Important Terms
Point Coordinates ↔ are lattice parameters. It can be used to define which plane is more denser.
Crystallographic Directions ↔ Line between two points.
Crystallographic Planes ↔ Set of equally spaced planes that may be supposed to pass through the center of atoms in a crystal.
Linear Atomic Density ↔ It is the ratio between number of atoms and unit length of direction vector.
Theoretical Density ↔ Crystal structure of metallic solid permits computation of its theoretical density through the relationship.
References:
Material from Class Lectures + Book named Materials Science and Engineering: An Introduction by Callister and Rethwick + my knowledge.
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...
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. Higher strain hardening capacity. Case Study of Automobile There are three different zones in a car: Crumple Zone (Front & Back) Middle Compartment Safety Cage Some important points about these zones are: 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 streng...
Comments
Post a Comment
HI, we wI'll contact you later