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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Friction
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Friction And it's Characteristics:
It is defined as;
A force which resists the movement of two contacting surface that slide relative to one another.
The force always acts tangent to the point of contact and is directed opposite to the existing motion between the surfaces.
Types of Dry Friction Problems:
There three types of problems of Dry Friction:
1. No Apparent Impending Motion:
The body is about to slip. For the body not to slip Fs ≥ Us N, otherwise the body may slip. Only equilibrium equations are used.
2. Impending Motion at all Points of Contact:
In this scenario, equilibrium equations as well as frictional motion equation are used.
3. Impending Motion at some Points of Contact:
The body might get slip. In this scenario, number of unknowns are less than the equilibrium and frictional motion equation.
Impending Motion:
Impending motion refers to the state just before the surfaces start to slip.
Tipping Effect:
The effect in which body rotate and fall on its side when the moment due to pushing force becomes greater than the moment due to the force of gravity.
Mpushing force ＞ Mgravity force
Difference Between Slipping and Tipping of a Body:
1. Slipping Effect:
When the pushing force will exceed the maximum static friction force and the box will begin to slide across the surface.
Fpushing force ＞ Ffrictional force
2. Tipping Effect:
When the pushing force and the friction force will create a strong enough couple that the box will rotate and fall on its side.
Mpushing force ＞ Mgravity force
Tipping Point:
When a body's center of gravity is above the area formed by the support base, the normal force can provide the necessary moment to remain in rotational equilibrium.
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...
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...
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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