BENDING MOMENT LAB

Summary

This video demonstrates a bending moment experiment on a simple supported beam to analyze the effects of bending moments. The objective is to determine the displacement at various points on the beam and calculate the bending moments for different loads. Copper and steel materials are used, with specific modulus of elasticity values. The procedure involves measuring displacement under various loads, recording data, and comparing theoretical and practical results. The video also covers calculations for reaction forces, shear force diagrams, and bending moment diagrams, providing a comprehensive overview of the experiment.

Takeaways

• 😀 Introduction to the Strength of Materials lab, focusing on a bending moment experiment.
• 😀 Objective: Students should compare the effects of bending moments on simply supported and cantilever beams.
• 😀 Key formula for displacement (f = P * L^3 / 3EI) is introduced, where P is force, L is beam length, E is modulus of elasticity, and I is the second area moment.
• 😀 The experiment uses materials like copper (E = 120 GPa) and steel (E = 200 GPa).
• 😀 The apparatus includes a gauge, ruler, steel bar, weight hanger, and a 5 Newton load.
• 😀 Procedure: Measure the steel bar, set up the apparatus, and hang the weights at designated points (P1 and P2).
• 😀 For P1, apply a 10 Newton load, and for P2, apply a 20 Newton load. Record data at gauges 1 and 2.
• 😀 The procedure is repeated for different beam lengths, with data recorded for each setup.
• 😀 Key steps in data analysis: calculate displacement at specific points on the beam, and draw shear force and bending moment diagrams for the simply supported beam.
• 😀 Compare practical and theoretical results to identify any discrepancies, and provide explanations for any observed differences.
• 😀 Conclusion and recommendation: Summarize findings related to reaction force and bending moments from the experiment.

Q & A

What is the main objective of the bending moment experiment?

The main objective is to compare the effect of bending moment on a simply supported beam and to determine the maximum point of the beam when a force is acting on it.

What is the equation for displacement (f) at the point where the force (P) acts on the beam?

The equation for displacement is f = P * L^3 / (3 * E * I), where f is the displacement, P is the force, L is the length of the beam, E is the modulus of elasticity, and I is the second area moment.

How is the second area moment (I) calculated for the beam?

The second area moment (I) is calculated using the formula I = B * D^3 / 12, where B is the width and D is the thickness of the beam.

What materials are used for the beam in the experiment, and what are their respective moduli of elasticity?

The materials used are copper and steel. The modulus of elasticity for copper is 120 GPa, and for steel, it is 200 GPa.

What apparatus are used in the bending moment experiment?

The apparatus used include a gauge, ruler, steel bar, weight hanger, and a load of 5 Newtons.

How do you set up the experiment to apply forces on the beam?

The apparatus should be set up by hanging the weight hangers at positions P1 and P2 on the steel bar. Then, a load of 10 Newtons is applied at P1 and 20 Newtons at P2.

What should be done after applying the loads on the beam?

After applying the loads, you should measure the displacement at the specified points using the gauges and record the data in a table for further analysis.

What is the procedure for repeating the experiment?

The procedure should be repeated for other beam lengths, and the corresponding displacement data should be recorded in the table for each length.

What should be included in the discussion section of the experiment?

In the discussion, you should calculate the displacement at specific points on the simply supported beam, draw the shear force diagram (SFD) and bending moment diagram (BMD), and determine the maximum bending moment point.

What should be compared in the experiment's conclusion?

In the conclusion, you should compare the theoretical and practical values of the bending moment, discuss any differences, and explain the reasons for any discrepancies.