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 ).
Principal Strain and stresses can occur in the same directions.
Material Properties Relation (Young, bulk Rigidity Modulus) ⇼ Hooke's Law
General State of Strain ⇼ ЄX, ЄY, ЄZ and ૪X, ૪Y, ૪Z.
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 of coordinate axes with ЄX (+ve right) and ૪Y/2(+ve upward).
Locate the center C of the circle at points ЄX1 = Єavg and ૪X1Y1= 0.
Locate point A which represents strain on X-face corresponds to (ЄX,૪Y/2).
Draw a line from point A to point C.
Using point C as center, draw Mohr's circle through point A.
Some key observations are:
Plane Strain ⇼ Stress condition in linear elastic fracture mechanics in which there is zero strain in the direction normal to the axis of applied tensile stress and direction of crack growth.
Principal Strain ⇼ maximum and minimum normal strain possible for a specific point on a structural element. Shear strain = 0 at the orientation where principal strain occurs. Important for predicting failure.
References:
Material from Class Lectures + Book named Engineering Mechanics of Materials by R.C. Hibbeler (6/9th Edition) + my knowledge.
Angles & Directions Angles are also called bearings. Bearings are the acute angles between lines and meridians. They are divided into following types. Related Terms : Meridian : Imaginary line joining North and South poles. Declination : Difference between magnetic and true meridians. Azimuth : Clockwise angle taken from Geodatic North. * If area is greater ➤ use Geodatic North * If area is smaller ➤ use Magnetic North Magnetic Declination maybe towards East or West. For east ➤ Magnetic bearing=true bearing - Declination For west ➤ Magnetic bearing=true bearing + Declination Forward Bearing : Bearing taken in the direction of traverse. Backward Bearing : Bearing taken in opposite direction of traverse. Forward bearing - Backward bearing=180 For anti-clockwise : FB of line = BB of previous line + angle Example: In an anti-clockwise traverse <A=102'30',...
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...
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 ⟺...
Comments
Post a Comment
HI, we wI'll contact you later