Understanding the stresses caused by bending is crucial because materials fail faster under bending. Take for example a biscuit, you don’t pull it axially to break it, but instead you bend it to break it. That’s because bending stress is greater than axial stress for the same force magnitude applied.
Here, we learn the formula to quantify bending stress:
Understanding the stresses caused by bending is crucial because materials fail faster under bending. Take for example a biscuit, you don’t pull it axially to break it, but instead you bend it to break it. That’s because bending stress is greater than axial stress for the same force magnitude applied.
Here, we learn the formula to quantify bending stress:
Notice that the higher the y the larger the bending stress. At y_{max} we have σ_{max}. Similar to the torsion formula, we denote y_{max} as c:
You might be wondering why is there a –ve sign in front of the bending stress formula. Here’s why:
The –ve sign in the formula gives the correct sign to the compressive stress based on the +ve sign convention of M and y. Similarly in the bottom region, y is –ve, and therefore using the formula we get a +ve stress (tension) which is correct.
Let’s look at an example now.
Notice that the higher the y the larger the bending stress. At y_{max} we have σ_{max}. Similar to the torsion formula, we denote y_{max} as c:
You might be wondering why is there a –ve sign in front of the bending stress formula. Here’s why:
The –ve sign in the formula gives the correct sign to the compressive stress based on the +ve sign convention of M and y. Similarly in the bottom region, y is –ve, and therefore using the formula we get a +ve stress (tension) which is correct.
Let’s look at an example now.