Spring Constant
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Posted by: erickson ® 02/22/2004, 20:18:03 Author Profile Mail author Edit

I would like to find an equation that will give me the spring constant of a thin plate based on its geometry. (length, width and thickness) I need this for two cases, pinned at its four corners and fastened along all four sides and both with a force at the center of the plate. I would also like to find out how to get the spring constant of a column under an axial load based on its geometery. (lenth, radius, solid or hollow, or mooment of inertia)

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Re: Spring Constant
Re: Spring Constant -- erickson	Post Reply	Top of thread	Forum

Posted by: Cragyon ® 02/25/2004, 10:42:24 Author Profile Mail author Edit

I think you can use one of the appropriate beam calculators here on Engineers Edge to determine a deflection load constant.   By experimenting with different loads you can come up with a rough estimate of the spring constant (deflection/load).   Link to /calculators.htm  and find "Beam Deflections and Stress" also check out   /strength_of_materials.htm

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Re: Spring Constant
Re: Re: Spring Constant -- Cragyon	Post Reply	Top of thread	Forum

Posted by: ReubenAG ® 03/09/2004, 15:57:43 Author Profile Mail author Edit

You can get an "exact" spring constant for the column as follows: For any beam loaded axially, Force = Spring Constant x Deflection For axial loads, Stress = Elastic Modulus (young's) x Strain Strain = Change in Length (deflection) / Total length Stress = Force /Area Hence Force/Area = Elastic modulus x Deflection/ Total Length Force = Area x Elastic Modulus x Deflection /Total Length Regrouping your terms, Spring Constant (also called stiffness) = Area x Elastic Modulus / Total Length   This holds for any axially loaded beam of constant cross section  - if the beam is circular and hollow, just work out the area and put it into the formula.

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