Material index formulas for optical clarity and Ashby charts

AI Thread Summary
Formulas for material selection using an Ashby chart focus on deriving material indices from equations related to deflection and thickness. The deflection equation for a spherical cap is given as d=(pr²)/2Et, leading to the material index m=pr³h𝝆/dE, where 𝝆/E should be minimized. For optical clarity in materials, particularly for a visor, the discussion highlights the need for a specific material index, although no direct equations for optical clarity are provided. It is noted that the reflectivity of clear materials increases with their Index of Refraction. Understanding these relationships is crucial for selecting suitable materials for applications requiring both structural integrity and optical properties.
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Hello:)

i need some help trying to find some formulas that i can retrive the material index from at the end of simplification to use with an ashby chart to select materials. here is an example of deflection equation from a sphere used for a spherical cap and what material index we used to find our material.

Deflection:
d=(pr²)/2Et
If mass is equal to density multiplied by volume, we can derive an equation for thickness:
m=𝞺at
m=𝞺(2rh)t
t=m/𝝆2rh
d=((pr²)/2E)*m/𝝆a solve for m to find the material index
m=pr³h𝝆/dE
𝝆/E is our material index and should be minimized, or E/𝝆 should be maximized.

the last material index i need to find is for optical clarity, how well you can see through it. We are making a visor for a helmet. So it needs to be clear and non reflective, but i don't know how to find the material index because i do not know of any equations used for optical clarity.

thanks.
 
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