Using this calculator you can visualise the shear force, bending moment and deflection of a cantilever beam when a point moment is applied at a distance 'a' from the wall support.
Calculations
Applied moment is positive (+) in the clockwise direction.
Inputs
Length of beam, L
:10.00m Distance from wall to Moment, a
:4.00m Magnitude of Moment, M0
:-5.00kN m Elastic Modulus, E
:200.00 GPa Second Moment of Inertia, SI
:142,000,000.00mm4 Cantilever beam with Point Moment
Outputs
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Explanation
Using Macaulay's Theorem and the Double Integration Method, we can create the equations for shear force, bending moment and deflection as follows:
- Shear Force
V(x)=−M<x−0>−1+V<x−0>0+M0<x−a>−1=V<x−0>0 - Bending Moment
M(x)=−M<x−0>0+V<x−0>1+M0<x−a>0 - Deflection
Y(x)=EI1[−2M<x−0>2+6V<x−0>3+2M0<x−0>2] Want to know how to derive the equations? Keep reading!
Derivation
Step 1: Find the beam support reactions by using the equilibrium equations.
ΣFy=0V=0
ΣM@x=0=0M=M0 Step 2: Find the shear force and bending moment equations by using the table of Macaulay's Singularity Functions on the homepage. There will be three terms in the and equations since there is and reaction at and applied moment at .
V(x)=−M<x−0>−1+V<x−0>0+M0<x−a>−1=V<x−0>0
M(x)=−M<x−0>0+V<x−0>1+M0<x−a>0 Step 3: Perform the Double Integration Method to find the deflection equation.
- Integrate the Bending moment equations once to get the Slope Equation.
θ(x)=EI1∫M(x)dxθ(x)=EI1[−M<x−0>1+2V<x−0>2+M0<x−a>1+C1] - Integrate the Slope Equation to find the Deflection Equation.
Y(x)=EI1∫θ(x)dxY(x)=EI1[−2M<x−0>2+6V<x−0>3+2M0<x−a>2C1x+C2] - Apply the Boundary Conditions to find the constants and
BC 1: @ x=0, θ(x)=00=EI1[−M<0−0>1+2V<0−0>2+M0<0−a>1+C1]0=EI1[0+0+0+C1]C1=0
BC 2: @ x=0, Y(x)=00=EI1[−2M<0−0>2+6V<0−0>3+2M0<0−a>2+C2]0=EI1[0+0+0+C2]C2=0 - Both constants are zero so you final Deflection equation becomes:
Y(x)=EI1[−2M<x−0>2+6V<x−0>3+2M0<x−0>2] You are now ready to plot the curves to determine the overall shear force, bending moment and deflection of a cantilever beam with a point moment!