# Thread: Bending moments and shear force diagrams

1. ## Bending moments and shear force diagrams

Draw the SFD and BMD diagram for the fallowing simply supported beams. Find the maximum deflection and state if is hogging or sagging.

Calculations:
For SFD Diagram
From the left side: SF=70-10x, x=distance
${SF}_1=70-10\times{}0$
${SF}_1=70kN$
${SF}_2=70-10\times{}1$
${SF}_2=60kN$
${SF}_3=70-10\times{}2$
${SF}_3=50kN$
${SF}_{3(output)}=50-40=10kN$
${SF}_4=70-10\times{}4$
${SF}_4=0kN$
In point of ${SF}_{4 }$ force shifts its magnitude.
From right side: SF=10x-50=distance
${SF}_5=10\times{}0-50$
Load force from top gives -40kN to ${SF}_{4 }$ on the output of liner force on the diagram.
${SF}_5=-50kN$
${SF}_6=10\times{}2-50$
${SF}_6=-30kN$
${SF}_7=10\times{}4-50$
${SF}_7=-10$
${SF}_8=10\times{}5-50$
${SF}_8=0kN$
For BMD diagram
From the left side: $BM=70×r-(10x^2)/2$
${BM}_1=70\times{}1-\frac{10\times{}1}{2}$
${BM}_1=65kNm$
${BM}_2=70\times{}2-\frac{10\times{}4}{2}$
${BM}_2=120kNm$
Calculation from right side:
${BM}_3=50\times{}2-\frac{10\times{}4}{2}$
${BM}_3=80kNm$
${BM}_4=50\times{}4-\frac{10\times{}16}{2}$
${BM}_4=120kNm$
Maximum deflection:
${BM}_5=50\times{}5-\frac{10\times{}25}{2}$
${BM}_5=125kNm$

2. Can you, do some calculation as well? Please.

3. Post has been updated. You can find useful data about how to count SFD and BMD diagrams.

4. You can make your own examples with android app given below. It finds shear forces and moments functions by using the method of sections and draws diagrams of these functions for isostatic straight beam.

5. Good, application. I will add this app to the mobile applications under software.

6. Thanks, for useful link. I going to start my uni course in September so, I need this sort of stuff going trough mechanical engineering.

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