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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Axial Loads
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Saint Venant's Principle:
It states that, "A system of forces applied to some segment of a solid body in equilibrium, produce stresses in the body that rapidly diminishes with increasing distance from the segment".
Elastic Deformation of an Axially Loaded Member:
To evaluate formula for deformation, consider diagram.
If system is statically indeterminate if it is held by more supports than are required to maintain its equilibrium (which creates more number of unknowns). We designate one of reactions as a Redundant to eliminate corresponding support.
Principle of Superposition states that: "Stress or displacements in complex loading are obtained by subdividing into components and later algebraically summing the stress or displacements caused by each load".
Conditions must be satisfied:
Loading must be linearly related to stress or displacement that is to be determined.
Loading must not significantly change the original geometry or configuration of member.
There are two types of analysis which are discussed ahead:
1. First Method of Analysis:
There are three steps for the First method of analysis for Indeterminate problem. Steps are given below:
Equilibrium equation.
Compatibility equation.
Stress-Strain relation or Deformation equation.
2. Flexibility or Force Method Analysis:
There are three steps for the Force method analysis for Indeterminate problem. Steps are given below:
Compatibility equation.
Stress-Strain relation or Deformation equation.
Equilibrium equation.
To solve statically indeterminate systems, consider following diagram:
Thermal Effects:
External loads are not the only source of stresses and strains in a structure. Thermal effects are commonly found in both mechanical and structural analysis (rise of stress and strain) that are open to atmosphere.
Changes in temperature, produce expansion or contraction of structural materials, resulting in thermal strain and stresses.
Thermal effects are more important in design of statically indeterminate structures than statically determinate ones.
References:
Material from Class Lectures + Book named Engineering Mechanics of Materials by R.C. Hibbeler (10th 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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