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.
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...
Comments
Post a Comment
HI, we wI'll contact you later