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 ).
Structural loads are the forces and moments applied to the structure. They are further divided into following types:
Surface loads ↔ externally applied load on the surface (like point load, line load, pressure, bending, torsion).
Body loads ↔ developed internally within the structure (gravity, weight, thermal load).
There are other types of loads with respect to time:
Static load ↔ if load is not a function of time (have constant magnitude, directions and location).
Dynamic load ↔ if load is a function of time.
Quasi-Static load ↔ if load varies slowly with time (taken as static load).
Dynamic loads are further divided as follows:
Steady-State loads ↔ which maintain same character (like frequency, amplitude, etc) over the long term.
Transient loads ↔ which change their character with time.
Taxonomy of Structure
Classification of structures (complex systems) by decomposing them into their simpler parts (structural elements). It is divided into 2 types:
Line Forming Elements (mostly beam)
Surface Forming Elements (Area and Volume Forming)
Determinancy of System
Determinancy of system is defined as, "if no. of unknowns is equal to the no. of equations".
If few constraints (less supports) than required ↔ structure is under-constraints and unstable.
i = m + r - 2( j )
Modelling and Analysis
The characteristics tasks in Structural analysis are:
Supports structural design
Understanding the complex response
Resultant stress and strain
Displacement to applied loads which gives strength and stiffness
The method of Structural analysis (Mathematical & Experimental analysis) involves 3 parts:
Equilibrium ↔ if body is in global equilibrium, every local particle is in equilibrium.
Static analysis ↔ implies negligible acceleration
Dynamic analysis ↔ motion of body including inertial forces
Deformation ↔ geometry of material displacement, strain (assuming continuous material, fully populated with particles) and Linear analysis (small displacement).
Constitution ↔ Stress and strain are intimately related to given material (or structural) system
Experimental Analysis involves:
Testing of real (or prototypical) structural techniques for strain.
Instruments: Extensometer, strain gages, optical interferometer, etc.
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...
Center of Gravity: It is defined as; The resultant weight of a system which passes through a single point is called Center of Gravity ( G ). Center of Mass: It is defined as; The point at which the whole mass of the system acts. The concept of center of mass is cleared from the video given below: Centroid of a Volume: Objects having three dimensions have the centroid which is its geometric centre. Centroid of an Area: Objects having two dimensions have the centroid which is its geometric centre. Centroid of a Line: Objects having linear dimensions have the centroid which is its geometric centre. Composite Bodies: A composite body consists of a series of connected simpler shaped Bodies which may be rectangular, triangular, semicircular, etc. References: www.youtube.com www.wikipedia.com http://web.aeromech.usyd.edu.au/statics/doc/friction/Friction1.htm From Book Engineering Mechanics sta...
Moving Boundary Work: The expansion and compression work associated with a piston cylinder device in which boundary moves is called Moving Boundary Work. Area under the Process curve on a PV Diagram: From the above figure, the differential area is the product of pressure and differential volume. So the area under the Process curve is given by: The area under the Process cure on a PV Diagram is Moving Boundary Work. Moving Boundary Work in A constant Volume Process: Moving boundary work is given by: Moving Boundary Work for a Constant Pressure Process: Moving Boundary Work is given by: Moving Boundary Work for an Isothermal Process: A thermodynamic process in which temperature remains constant durine the heat transfer is called Isothermal Process. Moving Boundary Work is given by: Where; PV = mRT If temperature is constant,then PV = c P = c/V Moving Boundary Work for P...
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