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...
Welded Joints A permanent joint which is obtained by the friction of edges of two parts to be joined, with or without the application of pressure and a filler material. Used in fabrication as an alternative method for casting and forging . Used as a repair medium . If filler material is used ↠ Strength of Joint > Base metal strength . If filler not used ↠ Joint strength < Base metal strength . Grinding Finish ↠ Welding at top and bottom off the plate. Machining Finish ↠ Welding at bottom surface after welding machining operation. Want to learn more about welded joint, click here . Designing of Butt Joint Design of Lap Joint or Fillet Joint Lap or Fillet joint is " formed by the overlapping of plates and then welding the edges of plates " . There are two types of fillet joints: Single and Double Transverse Fillet Joints ↣ are designed for tensile loading. Parallel Fillet Joints ↣ are designe...
Pressure: Pressure is defined as: ' Normal force per unit area of body'. There are different pressures which we described ahead: Atmospheric Pressure ⟺ Pressure exerted by atmosphere. Absolute Pressure ⟺ The actual pressure at a given point. It is calculated with respect to absolute zero pressure. Gage Pressure ⟺ It is difference between the absolute pressure and the local atmospheric pressure. Vacuum Pressure ⟺ Pressure below atmospheric pressure. Pressure At A Point In A Fluid: For the pressure at a point in fluid, consider a triangular area of fluid. Consider a free body diagram with in a fluid mass. The force and weight components along Z-axis is given by: So, pressure at a point of a fluid at rest or motion is independent of direction as long as there are no shearing stresses present. Types Of Forces: There are two types of forces which are described ahead: Body Forces ⟺...
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