# Lab Report Bending of a simply supported beam

Aim

“To study deflection in a simply supported beam”

This lab is aimed to study the behavior of simply supported beam under the action of a point load.

Objectives

The goal of comprehending the simply supported beam in an effective way can be achieved through step by step approach. It is very important that we follow the below given steps in the same order as they are listed.

Grasp the basic design of the beam and its working

Strain produced in the beam under the action of load

Perform experiment to study the strain produced in the beam and using strain gauge to measure strain

Introduction

Beam

Beam is one of the simplest but very important component of every structure or building. A simply supported beam has supports at both ends. It features roller support at one end and pinned support at the other. These beams can undergo both bending and shear stress. Therefore, these beams should be designed such that they are able to bear shear and bending stress applied on them.

Bending stresses in beam

When a beam is under the action of any load, reactions are produced at its supports which subsequently generate stresses within the beam. These stresses act to curve the beam about its supports. Therefore, these stresses are called bending stresses. Moreover, in bending the layers above neutral axis of the beam will be subjected to compression whereas bottom layers will be subjected to tension.

Deflection of beam

Once the bending stress produced in the beam surpasses a certain value, beam starts to alter its shape and it moves in the direction of applied load. This deformation phenomenon is known as deflection of the beam. Mathematically, it can be expressed as,

Maximum deflection=  (W × L^3)/(48 × E × I)

Where

L is the length of the beam

I is the moment of inertia of the beam

E is the modulus of elasticity of the beam

Modulus of elasticity

Young’s Modulus of elasticity of a material defines its ability to withstand the applied load remaining within its elastic limit. In a way, this property can also indicate the strain produced in a material. Mathematically, this can be obtained by simply dividing stress by strain.

modulus of elasticity=E=Stress/Strain

Moment of inertia

It is the geometric property of the beam. This property tells us about the resistance that a beam offers against angular motion when it is subjected to a stress.

Mathematically, it is expressed as,

I =  1/12  × b × h^3

Procedure

Experiment to find the deflection in a simply supported beam has following steps:

First of all, place the apparatus on a flat horizontal surface. Carefully, mount the dial gauge and attach load hanger to the apparatus.

Take all necessary measurements of the beam and also measure the distance of the point where the force or load is being applied. Use the above formulas to calculate the deflection theoretically.

Now, use load hanger to exert a load of 100 grams at the center of the beam.

Use strain gauge to note the value strain produced.

Repeat step iii and iv for different weights available in the laboratory and compare the experimental reading with the theoretical readings.