Shear forces and bending moments, Mechanical Engineering

Assignment Help:

Shear Forces and Bending Moments:

  • A beam is a structural member, subjected to a system of external forces (involving inclined load) to generate the bending of the member in an axial plane.
  • At the cross-section of the beam the shear force is explained as the unbalanced vertical force either to the right or to the left of the section.
  • The bending moment at cross section of the beam is explained as the algebraic sum of moments of all of the forces acting on the beam either to the right or to the left of the section.
  • All of the upward forces to the left of the section and all of the downward forces to the right of section cause positive shear force. All of the downward forces to the left of the section & all of the upward forces to the right of the section cause negative shear force.
  • The BM is called to be positive, while it is acting in an anticlockwise direction to the left of the section and clockwise direction to the right of the section. The BM is called to be negative, while it is acting in clockwise direction to the left of the section & an anticlockwise direction to the right of the section.
  • Whereas drawing SF and BM diagrams, all of the positive values are plotted above the base line & the negative values below it.
  • The maximum BM takes place, where the SF is zero or changes sign.
  • If the SF diagram line is horizontal among two points, the BM diagram is inclined. It denoted there is no load among two points. If the SF diagram is inclined among two points, the BM diagram is a parabola of second degree. It denotes that there is a uniformly distributed load among the two points. If the SF diagram is in the form of parabola of second degree among two points, the BM diagram is in the form of parabola of third degree (cubic parabola). It denote that there is a uniformly varying load among the two points.
  • The point of contraflexure is a point whereas the BM is zero or changes sign.
  • If a beam is subjected to a couple, the SF does not modify. But the bending moment suddenly changes in magnitude equivalent to that of the couple.
  • If there is a point load or reaction, the BM does not alter at that point. But the SF suddenly modifies (either decreases or increases) in magnitude equivalent to that of point load or support reaction.
  • If a beam is subjected to inclined loads, their components at right angles to the axis of components (vertical components) shall cause shear force & bending moment and their components along the axis of the beam (horizontal components) shall cause axial force or thrust in the beam.
  • Whereas drawing axial forces diagram, tensile forces are taken as positive & compressive forces are taken as -ve.

 


Related Discussions:- Shear forces and bending moments

Calculate the pressure using density , An open test tube at 293 K is filled...

An open test tube at 293 K is filled at the bottom with 24.2 cm of Hg, and 11.2 cm of water is placed above the Hg. Calculate the pressure at the bottom of the test tube if the atm

Electron beam welding(ebw)-basic principle, BASIC PRINCIPLE OF ELECTRON BEA...

BASIC PRINCIPLE OF ELECTRON BEAM WELDING(EBW)   Electron beam welding which utilises a heat source of electrons which are accelerated by an electric field to mextremely high

Belt friction, Ask question # how to derive a expression for the centifugal...

Ask question # how to derive a expression for the centifugal tension in belt driver

Objectives of basic troubleshooting of motorcycle , Objectives After s...

Objectives After studying basics troubleshoot of motorcycle, you should be able to check, perform inspection and identify the reason(s) of various problems reported by

Application of cost-volume-profit relationships, Application of Cost-Volume...

Application of Cost-Volume-Profit Relationships: Quality stores open for 10 hours a day. Company is considering decreasing the store hours through one hour. This shall resul

Discover the maximum torque, Discover the maximum torque: Discover the...

Discover the maximum torque: Discover the maximum torque that may be transmitted by the shaft of 400 mm diameter, if the shear stress is not to exceed 50 N/mm 2 . Solution

What is warm extrusion, Q. What is Warm extrusion? • Warm extrusion is ...

Q. What is Warm extrusion? • Warm extrusion is done above room temperature, but below the recrystallization temperature of the material the temperatures ranges from 424 to 975

Expression for strain energy, Expression for strain energy: Derive an...

Expression for strain energy: Derive an expression for strain energy because of torsion.                                          Sol.: The work done in straining shaf

Evaluate the gyroscopic couple, The turbine rotor of a ship having a mass o...

The turbine rotor of a ship having a mass of 200Kg moves at 200 r.p.m and its radius of gyration is 0.30 m. If the rotation of the rotor is clockwise looking from the aft., evaluat

Evaluate the principal stresses and principal planes, At a fixed point in a...

At a fixed point in a strained material the intensities of normal stress on the planes at right angles to each other are 20 N/mm 2 and 10 N/mm 2 . Evaluate the principal stresses

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd