Calculating Max Bending Moment: Physics Advice Needed

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In summary, the conversation is about calculating the maximum bending moment in a beam that is 3 meters long and carries two point loads. The suggested method is to plot the shear force and bending moment diagrams and manually find the maximum point, although an equation could also be used. The conversation also includes advice on maintaining significant digits in calculations and labeling points in diagrams.
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charger9198
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Physics advice please?
If a question was to ask, calculate the maximum bending moment

Could I find out the shear force points and graph it, then calculate and plot the bending points and manually find the max by observing the highest peak or is there an equation I should use?

The beam is 3 meters long. Simply supported at either end and carries two point loads, one at 1m (5kn) and the second at 2m (10kn). No u.d.l

Can someone advise me of the best way. Bearing in mind the question says calculate?

For my resistance I get x1 to be 6.7kn and x2 at 8.3kn.

For my shear force diagram I get +6.7 for m1, +1.7 for m2 and -8.3 for m3

Bending diagram I get at m1 to be +6.7, m2 to be +8.4 and m3 to be +0.2

Am I correct so far or have I over complicated things when I could have used an equation?
 
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  • #2
charger9198: Nice work. However, the unit symbol for kiloNewton is kN, not kn. Lowercase n means nano. Also, always leave a space between a numeric value and its following unit symbol. E.g., 10 kN, not 10kN.

Generally always maintain at least four significant digits throughout all your intermediate calculations, then round only the final answer to three significant digits. E.g., 6.667 kN, not 6.7 kN. Your numbers are too rounded, and this may have caused your final answer to be slightly inaccurate. Also, points are usually labeled with letters (A, B, C, D), so I do not really know what you mean by m1, m2, m3.

From your plot, you can manually see that the maximum bending moment occurs at point C. Therefore, you can compute the maximum bending moment at point C (as I think you already did). Except round it to three significant digits of precision, not two. Also, your moment at point D is currently incorrect.
 
  • #3
nvn: Many thanks for the advice, i re-calculated accordingly and seemed to get more accurate answers
0
A= +6.667 kN
B= +8.334 kN
c= +0.001 kN

I shall draw the shear force and bending moment diagram inline with the given and show the maximum bending moment to be +8.334 kN 2m from point A
 

1. What is the formula for calculating max bending moment?

The formula for calculating max bending moment is M = F * d, where M is the maximum bending moment, F is the applied force, and d is the distance from the applied force to the point of interest.

2. How do I determine the direction of the max bending moment?

The direction of the max bending moment depends on the direction of the applied force and the orientation of the object. If the applied force is perpendicular to the object, the max bending moment will be in the same direction. If the force is at an angle, the max bending moment will be perpendicular to both the force and the object.

3. What factors affect the max bending moment?

The max bending moment is affected by the magnitude and direction of the applied force, as well as the properties and geometry of the object, such as its shape, material, and support conditions.

4. How do I calculate the max bending moment for a complex object?

To calculate the max bending moment for a complex object, you will need to break it down into smaller, simpler shapes and calculate the bending moment for each of those shapes. Then, you can sum up the individual bending moments to find the total max bending moment.

5. What are some real-world applications of calculating max bending moment?

Calculating max bending moment is important in structural engineering, as it helps determine the strength and stability of buildings, bridges, and other structures. It is also useful in designing and analyzing mechanical systems, such as cranes, beams, and machine parts. Additionally, understanding max bending moment can help prevent material failure and ensure safety in various industries, such as construction and manufacturing.

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