ZIMSEC O Level Combined Science Notes: Loading a beam
- When a beam is loaded it will bend
- Bending movement creates stress
- The top of the beam is compressed and the underside is stretched
- This is because there are compressive forces at the top and stretching/tensile forces at the underside
- If the tensile force is greater than the tensile strength of the material it cracks on its underside
- tensile strength-the resistance of a material to breaking under tension
- If a beam is only supported on the centre tension forces occur at the top of the beam and compression on the underside
- The central axis of the beam is called the neutral axis
- Neutral axis-is that part of the beam that remains unstressed when the beam is bent/carrying a load
- The section above the neutral axis shortens (due to compression)
- The section below the neutral axis lengthens (due to tension)
- The length of the neutral axis does not change.
- Please note that on a centrally supported beam the section above the neutral axis lengthens and the one below shortens
- On a loaded beam the tension are equal to the compression forces bu they act in the opposite direction
- The greater the distance is from neutral axis the greater the tensile and compression forces
To access more topics go to the Combined Science Notes page.
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