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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Orthographic Projections
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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 inclined to a plane of projection appear as foreshortened lines.
Curved edges project as straight lines on the plane of projection to which they are perpendicular.
Curved edges project as curved lines on the planes to which they are parallel or inclined.
Normal surfaces appear as an edge in two opposite principal views, and appear as surface in all other principal views.
Inclined surfaces appear as an edge in two opposite principal views, and appear foreshortened in all other principal views.
Six Principal Views of Orthographic Projection:
Six principal view of orthographic projection are:
How We Draw Views Of Orthographic Projection:
The figure shows how we draw views of orthographic projection and co-relate them with each other.
How We Choose The Front View:
It is the most important step taken when you start to draw views of Orthographic Projections. You should follow guidelines to get your path correct.
Front view should have minimum hidden lines.
The view should be stable.
Most basic profile should be used.
Types Of Projections:
There are two types of projections, namely:
First Angle Projection
Third Angle Projection
1. First Angle Projection:
2. Third Angle Projection:
Symbols Of Angles of Projections:
You should draw these symbols if you are going to draw views of Orthographic Projection.
TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions. 1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small. It is given by the formula, C t = 𝛼 (T m – T o )L Where, C t = the correction for temperature, in m. 𝛼 = the coefficient of thermal expansion. T m = the mean temperature during measurement. T o = the tempe...
Diffusion It is defined as, " The transportation of one atom from one state into other state " . Used for hardening of surfaces like die parts, gear, bolt, machine element. Hardening can be done using Temperature-Heat treatment ( diffusion couple ). There are two types of diffusion: Inter-diffusion ↔ in which atoms tend to migrate from region of high concentration to low concentration . Self-diffusion ↔ in which atoms migrate within a solid. Diffusion Mechanism There can be two conditions of moving atoms Empty spaces between adjacent sites. Atoms have sufficient energy to break bond with neighbors atoms which cause lattice distortion during displacement. If we rise temperature, small fractions of atoms is capable of diffusive motion (which cause lattice distortion). Types of Diffusion 1. Vacancy Diffusion It is defined as, " interchange of an atom from a normal lattice position to the adjacent vacant lattice site " . Extent of vacancy diffusion is a function...
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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