Help finding deflection of beam

In summary, there are three contributions to the deflection at B: the deflection of DC, the spread force q, and the axial force and deflection of AB. To find the deflection, the axial extension of DC must be determined by knowing the force in CD. The expressions for M(x) in the conversation are incorrect, as one of the terms is not calculated using the correct definition of moment. The location of C' in relation to C must be determined in order to accurately represent the deflection. Additionally, Mohr's theorems for slope and deflection can be applied to this problem.
  • #1
Dell
590
0
find the deflection of the beam at point B
Capture.JPG


i drew the free body diagram of the beam and found that
Ay=0
Ax=qL
Cy=qL
Cx=qL
Untitled.jpg


M(x)= (qL)*x - (qx)*x/2 +(qL)*<x-L/2>

M(x)=(qL)x -(q/2)x2 +(qL)<x-L/2>

EIΦ(x)=(qL/2)x2 -(q/6)x3 +(qL/2)<x-L/2>2 + C1

EIY(x)=(qL/6)x3 -(q/24)x4 +(qL/6)<x-L/2>3 + C1*x + C2

EIY(0)=0= 0+ C2
===>c2=0

but i need another condition to find C1, i think i need to use the deflection of the bar DC somehow, but I am not quite sure how, i tried using triangles and saying that the deflection of point C is the same as the deflection of the bar DC*sin(45) but that didnt work
 
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  • #2
There are 3 contributions to the deflection at B. Can you identify them? One of them is the extension of CD, as you have realized. If you know the force in CD, you should be able to work out its axial extension. By the way I don't agree your expressions for M(x). In each case one of the terms is not right. The definition of a moment is force times PERPENDICULAR distance. Look at it again. The moment at a section is the algebraic sum of moments on one side of that section. So it can always be checked by looking at the other side of the section; you should then get the same result.
 
  • #3
pongo38 said:
There are 3 contributions to the deflection at B. Can you identify them? .

1) the deflectin of DC,
2) the spread force q
3)the axial force and deflection of AB?

if this is so, how do i find it?? the area of AB is not given
 
  • #4
Let's say that C moves to C' as a result of the axial extension of DC. Where is C' in relation to C? Try sketching the exaggerated shape of the deflection as accurately as you can. Your remark that you don't know the area A is also true of EI for the beam. So I assume you are just developing a formula as an answer. CB is a cantilever extension to a beam. What is the difference between that and a cantilever built into a wall rigidly? I think you will find Mohr's theorems for slope and deflection applicable to this problem. Does that help?
 

1. What is deflection of a beam?

The deflection of a beam refers to the amount of bending or deformation that occurs when a beam is subjected to a load or force.

2. How do you calculate the deflection of a beam?

The deflection of a beam can be calculated using the equation: D = (W * L^3) / (3 * E * I), where D is the deflection, W is the load, L is the length of the beam, E is the Young's modulus, and I is the area moment of inertia.

3. Can the deflection of a beam be measured?

Yes, the deflection of a beam can be measured using specialized instruments such as deflection gauges or displacement transducers. These instruments can provide precise measurements of the amount of deflection at different points along the beam.

4. How does the material of the beam affect its deflection?

The material of the beam plays a significant role in determining its deflection. Different materials have different properties such as Young's modulus, which directly affects the beam's stiffness and therefore its deflection under a given load.

5. What factors can influence the deflection of a beam?

The deflection of a beam can be influenced by various factors such as the load applied, the length of the beam, the material of the beam, the type of support used, and the cross-sectional shape of the beam. Other factors such as temperature changes, moisture content, and external forces can also affect the deflection of a beam.

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