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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Cotter and Knuckle Joints
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Cotter Joints
A temporary fastener used to connect rigidly two co-axial rods (or bars) which are subjected to axial tensile or compressive forces.
Cotter ↣ A flat wedge shaped piece of rectangular cross-section of uniform thickness and its width is tapered for an easy adjustment.It is made of steel.
Used in connecting piston rod to cross-head of reciprocating steam engine.
Inserted ⊥ to the axis of shaft.
Strength of key < Cotter strength ↣ because of removing material.
We add taper on top of key while we add taper on top, bottom but along width side of cotter.
Types of Cotter Joint
1. Sleeve and Cotter Joints
Simplest of all cotter joints and is used to fasten two round rods/bars.
Rectangular cross-section area, tapered both sides along width.
We add cotter pin ⊥ to the axis of shaft and add sleeve to shaft and then add pin.
It has better strength than Socket and Spigot Cotter joint.
Taper in cotter is 1 in 24.
2. Gib and Cotter Joints
It is used to join two square rods but round rods can be joined with suitable modification.
One end of rod is U-fork shaped and the other is of square end.
Gib ↣ C-shaped added to provide strength to joints (for greater load bearing area and holding force between cotter and rods).
Lug ↣ one side of gib is tapered and the other is straight with 2 rectangular projections which get U-shaped rod and rod together then we add cotter pin.
3. Socket and Spigot Cotter Joint
Used to connect 2 circular rods to carry both tensile and compressive loads.
One end is provided with a socket by enlarging its end.
Spigot ↣ Other rod is inserted into socket.
Design of Socket and Spigot Cotter Joint
Knuckle Joint
Mechanical joint used to connect two rods which are under a tensile load.
One of the rod can be positioned through some angle about the plane containing rods.
Cross-section of Knuckle is circular.
It contains two ends, end of one rod is made into fork (double eye) and the other rod end is made into eye.
Pin is inserted and they are held by means of collar and a taper pin.
Design of Knuckle Joint
References:
Material from Class Lectures + Book named Mechanical Engineering Design by Shigley (8th Edition) + my knowledge.
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...
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...
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...
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