Problem with Buckling of stepped bar Roark's Formula's

[RaymondSE]

Hello,

I have a problem with calculating buckling on a stepped bar with roark's formulas for stress and strain.

By these tables (page 718-722) they show tables where you can find K1 values to calculate the maximum buckling load.
In these tables you compare:
-(E2I2/E1I1) E is youngs modulus and I is moment of inertia.
-A/L The ratio of length of upper and lower part.
-The ratio between P1 and P2

In my case:
P2 = 0.
A/L = 0.65
But E2I2/E1I1 = 3.36

This value is not tabulated.
Does anyone know how can I find K1 for this value.

Raymond

 

[Achy47]

Hello Raymond,

Thank you for sharing your problem with us. Calculating buckling on a stepped bar using Roark's formulas can be a complex task, but there are a few steps you can take to find the K1 value for your specific case.

First, make sure you are using the correct equations for your specific type of stepped bar. There are different equations for different types of bars, such as square, rectangular, or circular cross-sections. Make sure you are using the correct equation for your particular bar.

Next, try to find a more precise value for E2I2/E1I1. This value is usually calculated using the moment of inertia for each section of the bar, so make sure you are using the correct values for the cross-sections of your stepped bar. You can also try to use a more precise value for E, which can be found through experiments or more accurate material data.

If you are still unable to find a tabulated value for your specific E2I2/E1I1 ratio, you can try interpolating between two tabulated values. This involves estimating the value between two known values and using a formula to calculate a more precise value. However, this method may not be as accurate as using a tabulated value, so use it with caution.

I hope these suggestions help you find the K1 value for your stepped bar. If you are still having trouble, you may want to consult with a colleague or expert in the field for further assistance. Good luck with your calculations!