Prof.Kodali Srinivas

Springs are energy absorbing units whose function is to store energy and to restore it slowly or rapidly depending on the particular application. A spring may be defined as an elastic member whose primary function is to deflect or distort under the action of applied load; it recovers its original shape when load is released. Helical spring:  They are made of wire coiled into a helical form, the load being applied along the axis of the helix. In these type of springs the major stresses is torsional shear stress due to twisting. They are both used in tension and compression. Derivation of the Formula : I n order to derive a formula which governs the deflection and stress of closed coil helical springs, consider a closed coiled spring subjected to an axial load W. with the fallowing Assumptions: 1. The Bending and shear Force effects may be neglect 2. For the purpose of derivation of formula, the helix angle is considered to be so small that it may be neglected.

IIf a body is subjected to Shear Force, Bending moment and Twisting moments, then the combined stress in the shaft will be calculated by using of principle of superposition. 1.Shear stress due to direct shear: The average Shear Stress due to direct shear force q = F/A Where F= Shear Force at the section A= Area of the cross section,  But the shear stress distribution in the section will get by using the equaction qd = FQ/Ib Where Q= Ay Where, A = Area between the extreme face of beam and the plane at which the shear stress is q y = Distance of the centroid of area from N.A F = Shear force at the cross-section. I = Moment of Inertia of the beam cross section about N.A. b = Width of the fiber at the plane at which shear stress is q 2.Shear stress due to Torsion: For solid or hollow shafts of uniform circular cross-section and constant wall thickness, the torsion relations are: where: R is the outer radius of the shaft. τ is the maximum

Assignment in Torsion: S.M.2, Unit-2 1.An aluminum shaft with a constant diameter of 50 mm is loaded by torques applied to gears attached to it as shown in Fig. Using G = 28 GPa, determine the relative angle of twist of gear D relative to gear A. 2.What is the minimum diameter of a solid steel shaft that will not twist through more than 3° in a 6-m length when subjected to a torque of 12 kN·m? What maximum shearing stress is developed? Use modulus of rigidity G = 83 GPa. (T=0.1138 d 4) 3.A solid steel shaft 5 m long is stressed at 80 MPa when twisted through 4°.  Using G = 83 GPa, compute the shaft diameter. What power can be transmitted by the shaft at 20 Hz? (P=5.19MW answer) 4.A steel propeller shaft is to transmit 4.5 MW at 3 Hz without exceeding a shearing stress of 50 MPa or twisting through more than 1° in a length of 26 diameters. Compute the proper diameter if G = 83 GPa. (diameter d = 352 mm answer) 5.Determine the maximum torque that can be applied to a hollow circ

The Shear centre is a point where a shear force can act without producing any twist in the section. At  Shear centre of a section the applied force is balanced by the set of shear forces obtained by summing the shear stresses over the section. Shear centre is also known as the centre of twist. When the load does not act through the shear center, in addition to bending, a twisting moment will develop  in the section.  The location of the shear center is independent of the direction and magnitude of the transverse forces. In unsymmetrical sections and in particular angle and channel sections, the summation of the Shear Stresses in each leg gives a set of Forces which must be in equilibrium with the applied Shearing Force. (a) Consider the angle section which is bending about a principal axis and with a Shearing Force F at right angle to this axis. The sum of the Shear Stresses produces a force in the direction of each leg as shown above. It is clear that their resultant passes through t

Engineering mechanics or Applied mechanics is  a branch of the physical sciences and the practical application of mechanics.  Much of modern engineering mechanics is based on Isaac Newton's laws of motion while the modern practice of their application can be traced back to Stephen Timoshenko, who is said to be the father of modern engineering mechanics.    Engineering Mechanics is divided into two parts Statics and Dynamics. Statics: It is a branch of mechanics which studies the effects and distribution of forces of rigid bodies which are and remain at rest. In this area of mechanics, the body in which forces are acting is assumed to be rigid .  The deformation of the body is treated in Mechanics in the name of Solid Mechanics or Strength of Materials. Force - It may be defined as any action that tends to change the state of rest of a body to which it is applied.  Newton's laws of motion are three physical laws that form the basis for classical mechanics.  Newton's

A tank or pipe carrying a fluid or gas under a pressure is subjected to tensile forces, which resist bursting, developed across longitudinal and transverse sections. If the thickness of the wall of the cylindrical vessel is less than 1/15 to 1/20 of its internal diameter,the cylindrical vessel is known as Thin Cylinder.  Tangential Stress (Circumferential Stress) or Hoop stress Consider the tank shown being subjected to an internal pressure p. The length of the tank is L and the wall thickness is t . Considering the right half of the tank:  The forces acting on this right half of the vessel are the total pressures F caused by the internal pressure p, and the total tension T in the walls. The projected area subjected to internal pressure = A = DL F = pxA = p.DL The tangential stress in the walls =  s t T =    s t  A wall =  s t .  tL But F = 2T  p.DL  = 2( s t .  tL)  The tangential stress  s t = pD/2t If there exist an external pressure po and an internal pressure pi, the the Tangent

In case of unsymmetrical sections, neutral axis will not pass through the geometrical centre of the section. In unsymmetrical beam sections the distance of  outermost layers i.e. for topmost layer and bottom layer of the section from neutral axis will not be same. In order to calculate the bending stress for unsymmetrical sections, we must have to find the value of centre of gravity (centroid) of the given unsymmetrical section. In order to calculate the maximum bending stress for unsymmetrical sections, we will use the bigger value of y. In this section, the following notation will be use:  fbt = flexure stress of fiber in tension fbc = flexure stress of fiber in compression N.A. = neutral axis I = Moment of Inertia about N.A yt = distance of fiber in tension from N.A. yc = distance of fiber in compression from N.A. M = resisting moment Mc = resisting moment in compression Mt = resisting moment in tension  Max.flexure stress in tension  f bt = (M/I).y t Max.flexure stress in compress

 MIST - Satthupalli (2001-2007)  Khammam Dist. T.S -

Prof. Kodali Srinivas' writings ప్రొఫెసర్ కొడాలి శ్రీనివాస్ - రచనలు 1.వాస్తు విద్య VAASTHU    VIDYA  (బృహత్ సంహితా భాగానికి విస్లేషణాత్మక తెలుగు అనువాదం -2007) వరాహ మిహిరుని చే ఆరోవ శతాబ్దం లో గ్రంధస్థం చేయబడిన బృహత్సంహితలోని ఒక భాగమే ఈ వాస్తు విద్య. తెలుగు లో తొలిసారి వెలువడిన ఈ గ్రంధం మన ప్రాచీన వాస్తు శాస్త్రాన్ని సంక్షిప్తంగా తెలియజేస్తుంది. తెలుగులో ప్రామాణిక వాస్తు గ్రంధాలు లేని కొరతను ఇది కొంతవరకు తీరుస్తుంది . 2. వాస్తు  లో    ఏముంది ? వాస్తు ఫై సమగ్ర పరిశోధ నా  గ్రంధం -   1997 VAASTHULO     EMUNDI ? లేని విషయాన్ని చెప్పటాన్ని  అబద్ధం  అంటారు . చిన్న విషయాన్ని పెద్దది చేసి భూతద్దంలో చుపటాన్ని  అతిశయోక్తి   అంటారు. విషయాన్ని సరిగ్గా అర్థం చేసుకోలేక పోవటాన్ని  అవగాహనారాహిత్యం అంటారు.నేడు సమాజంలో విరివిగా అనేక అబద్దాలు ,అతిశయోక్తులు వాస్తు పేరుతొ వాస్తవాలుగా చెలామణీ అవుతున్నాయి ఈ అశాస్త్రీయ మైన వాస్తును అనేకమంది అవగాహనారహిత్యంతో అతిగా ఆచరిస్తున్నారు  . ఈశాన్నం లో నుయ్యి ,ఆగ్నేయంలో పొయ్యి ...వాస్తు అంటే ఇదే అనే భ్రమను తొలగించి వాస్తవాన్ని మీముందు ఉంచుతుంది .సాంకేతిక దృష్టి

"Believe nothing, merely because you have been told it or because it is traditional or because you yourself have imagined it" - Buddha . I n recent times there has been a sudden upsurge of interest in Vaastu. People are spending a lot of money and efforts in the name of Vaastu. Now it is a universal affair throughout the country. We must examine the relevance of traditional vaastu for present day structures. Vaastu is derived from the Sanskrit root “Vas” which means to dwell. Vaastu is hence a dwelling, the scope of which extends from a house to a house plot, a hamlet, a village, a town, a city etc.; it also represents the quality and strength of materials which are generally used in the construction of buildings.   Vaastu Shastra is basically a science of planning and construction of houses and other public buildings. It is developed by several ancient scholars and sages at various places in different times for orderly growth of settlements. The original principles have

II B.Tech. Civil - First Semester ANU - SYLLABUS UNIT-1 STRESS Introduction,Method of sections; Definition of stress;Normal stresses in axially loaded bars;Shear stresses; Allowable stress and Factor of safety. STRAIN Normal strain; Stress- Strain relationships; Hooke's Law, Poisson's ratio;Thermal strain and deformations of axially loaded bars,statically indeterminate bars,Stress-Strain relationship for Shear. GENERALIZED HOOKE'S LAW  and PRESSURE VESSELS Generalized Hooke's law for isotropic materials; Relationship between Modulus of elasticity and Modulus of rigidity; Bulk modulus;  Thin-walled pressure vessels - cylindrical and spherical vessels. UNIT - II INTERNAL FORCES IN BEAMS Introduction; Diagrammatic conventions for supports,loads; Calculation of reactions, Shear force and Bending moment in beams. Shear force and Bending moment diagrams;Differential equations of equilibrium for a beam element. UNIT - III INORMAL STRESSES IN BEAMS Introduction; Basic assumptio