Need help with multi-segment deflection problem

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In summary, the problem involves a uniform, horizontal beam with a length of 4.8m supported by a pin and a roller. There is a distributed weight of 12kN/m from x=0 to x=1.6m and a concentrated force of 2.4kN at x=4.8m. The goal is to find the deflection and coefficients of integration for each segment using the equation EIY'' = double integral of Mdx, where Y is the deflection. The calculated moments for each segment are M1=13.2x-6x^2, M2=-6x+15.36, and M3=2.4x-11.52. To
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Strawberry
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Homework Statement


There is a uniform, horizontal beam 4.8m in length supported by a pin at x = 0 and a roller at x= 3.2m. There is a distributed weight of 12kN/m from x = 0 to x = 1.6m. There is a concentrated, vertical force of 2.4kN in the downward direction at x = 4.8.
Find the deflection and define the coefficients of integration for each segment

Homework Equations


EIY'' = double integral of Mdx
Y is deflection

The Attempt at a Solution


I calculated the moment for each segment, but I can't seem to figure out what the coefficients are. I think I'm supposed to use symmetry conditions, and I know the deflection is 0 at x = 0 and x = 3.2 where there are supports. I can't figure out past that though.

M1 = 13.2x - 6x^2
M2 = -6x + 15.36
M3 = 2.4x - 11.52

EIV1 = 2.2x^3 - .5x^5 + C1x + C2
C2 = 0

EIV2 = -x^3 + 7.68x^2 + C1x + C2

EIV3 = .4x^3 - 5.76x^2 + C1x + C2

I believe the moments I calculated are correct, but I'm not sure. Any help would be appreciated.
 
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  • #2
Oh, I think I figured it out. V' is 0 at x = 1.1, from there I can find the rest of the coefficients
 
  • #3


I would suggest using the Moment-Area Method to solve this multi-segment deflection problem. This method involves finding the area under the moment diagram for each segment and using it to determine the deflection at that point. The coefficients of integration can be found by applying the boundary conditions (symmetry conditions in this case) and solving for them.

First, we can find the area under the moment diagram for each segment using the equations given in the problem.
For segment 1 (0 ≤ x ≤ 1.6):
Area = ∫(13.2x - 6x^2)dx = 13.2x^2/2 - 6x^3/3 = 6.6x^2 - 2x^3 + C1
For segment 2 (1.6 ≤ x ≤ 3.2):
Area = ∫(-6x + 15.36)dx = -3x^2 + 15.36x + C2
For segment 3 (3.2 ≤ x ≤ 4.8):
Area = ∫(2.4x - 11.52)dx = 1.2x^2 - 11.52x + C3

Next, we can apply the boundary conditions to solve for the coefficients of integration. Since the deflection is 0 at x = 0 and x = 3.2, we can set the deflection equations for segments 1 and 2 equal to 0 at those points. This gives us:
For segment 1 (x = 0):
0 = 6.6(0)^2 - 2(0)^3 + C1
C1 = 0
For segment 2 (x = 3.2):
0 = -3(3.2)^2 + 15.36(3.2) + C2
C2 = 30.72 - 30.72 = 0

Finally, we can solve for the deflection at x = 4.8 by setting the equation for segment 3 equal to the given concentrated force of 2.4kN:
2.4 = 1.2(4.8)^2 - 11.52(4.8) + C3
C3 = 27.648 - 55.296 + 2.4 = -25.248
 

FAQ: Need help with multi-segment deflection problem

What is a multi-segment deflection problem?

A multi-segment deflection problem is a mathematical or engineering problem that involves calculating the amount of deflection or bending of a structure that is composed of multiple segments or sections. The problem often involves determining the forces or loads acting on each segment and using equations and principles of mechanics to calculate the overall deflection of the structure.

Why is it important to solve multi-segment deflection problems?

Solving multi-segment deflection problems is important in various fields of science and engineering, such as civil engineering, mechanical engineering, and materials science. It allows us to analyze and design structures to ensure they can withstand the expected loads and forces and prevent failure or collapse. It also helps in optimizing the design and materials used, leading to more efficient and cost-effective structures.

What are some common methods used to solve multi-segment deflection problems?

Some common methods used to solve multi-segment deflection problems include the moment-area method, the conjugate-beam method, and the method of virtual work. These methods use principles of mechanics and mathematical equations to analyze the forces and deflection of each segment and determine the overall deflection of the structure.

What are some challenges in solving multi-segment deflection problems?

One of the main challenges in solving multi-segment deflection problems is the complexity of the structure and the number of unknown variables. This can make the calculations and equations involved quite lengthy and difficult to solve manually. Additionally, accurate and detailed data on the material properties and loads acting on the structure are crucial for obtaining accurate results.

Are there any software programs available to assist with solving multi-segment deflection problems?

Yes, there are several software programs available that can assist with solving multi-segment deflection problems. These programs use numerical methods and algorithms to quickly and accurately solve complex deflection problems. However, it is important to understand the underlying principles and assumptions behind these programs to ensure accurate results.

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