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.
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...
Solid Mechanics OR Mechanics of Materials OR Strength of Materials: It is the study of mechanics of body i.e. forces and their effects on deformable solids under different loading conditions. Deformable Body Mechanics: It is the study of non-rigid solid structures which deform under load. Deformation/Distortion ⇾ change of shape and size OR have some relative displacement or rotation of particles. It happens when we apply combined load. Rigid Body Motion ⇾ Translation or rotation of particles but having constant distance between particles. Since deformation occur at particular load. Below this load, every body is considered as rigid body . Types of Load: Point Load ⇾ Load apply on a single point i.e. concentrated load. Uniformly Distributed Load (UDL) ⇾ Load remains uniform throughout an area of element like beam. Varying Distributed Load (VDL) ⇾ Load varies with length with constant rate. Moment ⇾ It measures the tend...
Strain Transformation Principal Strain and stresses can occur in the same directions. Material Properties Relation (Young, bulk Rigidity Modulus) ⇼ Hooke's Law General State of Strain ⇼ Є X , Є Y , Є Z and ૪ X , ૪ Y , ૪ Z . Stress (normal or shear)/ Strain (normal or shear) ⇼ vary with element orientation. Transformation equations for Plane strain derived from: Interpretation of Experimental measurements Represent in graphical form for plane strain (Mohr's Circle). Geometry and independent of material properties. Mohr's Circle It is defined as., " A graphical method for determining normal and shear Shear stresses without using the stress transformation equations " . While considering the circle CCW ⇼ Shear strain positive upward & Normal strain positive towards right. The construction of Mohr's circle (with normal and shear stresses are known) is quite easy which include following steps: Draw a set o...
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