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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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