To perform bending test on a wooden beam

Job # 7

To perform bending test on a wooden beam

Objective:

1. To study the bending behavior of a wooden beam
2. To determine the modulus of rupture and modulus of elasticity of beam

Apparatus:

1. 10 ton Buckton UTM
2. Wooden beam
3. 3 deflection gages
4. Measuring tape

Related theory:

1. Bending moment:

The algebraic sum of moment of all the transverse forces acting on either the left or right side of any section about this section is called bending moment at this location.

2. Shear force:

A force which tends to slide one part of a section against the adjacent.

3. Elastic curve:

The deflected shape of the beam after the application of load (in elastic range).

4. Bending stress/ flexural stress:

The stresses caused by bending moment are known as bending or flexural stresses.

5. Bending formula/ flexural formula:

The relation between these stresses and the bending moment is expressed by flexural formula:

$\sigma =\frac{My}{I }$

6. Modulus of rupture:

It is the maximum tensile stress which can be developed in the beam before failure.

No of obs.	Load		Deflection gage reading				$∆=(Gc–mean)\times L.C\times 25.4$
			Gx	Gy	$(Gx+Gy)/2$	Gc
	ton	N	in	in	in	in	mm
1	0	0	100	100	100	200	2.54
2	0.05	445	110	110	110	210	2.54
3	0.1	890	120	120	120	230	2.794
4	0.15	1335	130	130	130	250	3.048
5	0.2	1780	140	140	140	260	3.048
6	0.25	2225	150	150	150	270	3.048
7	0.3	2670	160	160	160	290	3.302
8	0.35	3115	190	190	190	325	3.429
9	0.4	3560	200	200	200	345	3.683
10	0.45	4005	220	220	220	365	3.683
11	0.5	4450	240	240	240	400	4.064

 

Observations and calculations:

a = 150 mm

b = h = 50 mm

l = 500 mm

Slope from graph =  

$P‘/d$

= 445

Maximum value of load = P = 2.05 tons = 18245 N