Beam deflection due to a point load with two pin jointed supports at either end.

Contents

Interface Function Documentation Page Comments

Interface

#include <codecogs/engineering/structures/deflection_pp.h>

using namespace Engineering::Structures;

double

deflection_pp (double L, double a, double W, double x, double EI=1) Beam deflection due to a point load with two pin jointed supports at either end.

Function Documentation

This function is used to calculate the deflection along a beam that is subjected to a single perpendicular point load W.

The deflection of the beam is calculated using the principal of virtual work, applying a unit load of 1N at the location where the deflection is required and solving where M(x) are the moment along the beam due to the applied unit load W, while M_u(x) is the moment due to the applied virtual point load at the location x.

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Example

Calculate the deflection along a 9m long solid plank of wood (100mm x 50m) wood due to a person that weights 70kg who stands 3m from either end.

In graphical form the deflection (negative is downwards) is given by:

#include<stdio.h>
#include<codecogs/engineering/structures/deflection_pp.h>
 
int main()
{
  double E=10e9;      // approximate strength of wood.
  double I=1.042e-6;  // I=b*h^3/12.
  double L=9;
  double a=3;
  double W=70*9.81; // Force in Newtons
  for(int x=0;x<=L;x++)
    printf("\n deflection(x=%d)=%lf",x,
      Engineering::Structures::deflection_pp(L, a, W, x, E*I));
  return 0;
}

Output:

deflection(x=0)=0.000000
deflection(x=1)=0.322188
deflection(x=2)=0.600441
deflection(x=3)=0.790825
deflection(x=4)=0.860389
deflection(x=5)=0.820115
deflection(x=6)=0.691972
deflection(x=7)=0.497927
deflection(x=8)=0.259947
deflection(x=9)=0.000000

Parameters:

L	The length of the beam. [m]
a	The location of the point load applied to the beam. [m]
W	The point load applied at location a in a direction perpendicular to the main beam. [N]
x	The point at which the deflection should be calculated
EI	The Modulus of Elasticity (E) multiplied with the Second Moment of Area (I) for the specified beam. See Young's Modulus for example values. [N/m^2]