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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Techniques to Examine Crystal Defects
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Microscopic Techniques
It is defined as, "techniques used to examine structural elements and defects in crystalline materials".
Microstructure ↠ combination of crystal structure + grain size + defects in crystal structure + phase + impurities.
Microscopy ↠ used for the investigation of microstructural features (instruments).
Applications of microscopy and micro-structure are:
Ensure association between the properties, structures and defects.
To predict property of material (after relationship created).
To design alloys with new property combination.
Check material has been properly heat treated.
To study various mode of mechanical fracture.
Types of Microscopy
1. Optical Microscopy
It is defined as, "microscopy in which visible light and system of lenses to magnify images of small samples". Upper limit magnification is 2000x.
It consists of two major systems, which are
Magnification System ↠ have lenses to magnify.
Illuminating System ↠ have light and camera for capturing images.
Metallographic investigation (optical microscopy of metals) consist of following steps:
Sectioning ↠ cutting of material to observe a structure of large crystal structure.
Grinding ↠ to remove buds over the surfaces.
Polishing ↠ to further smoothen the surface.
Etching ↠ workpiece is dipped in Nitric Acid to highlight boundaries.
2. Electron Microscopy
It is defined as, "microscopy in which image of investigated structure is formed using beams of electrons".
Magnification power is smaller than that of optical microscopy.
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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