×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

ASTM F 382

ASTM F 382

ASTM F 382

(OP)
This standard is for the static bending properties of metallic bone plates. My question is how the equation for Bending stiffness was derived. The equation they give is the following:

Bending Stiffness = (5/324)*B^3 * Bending rigidity

Where: B = distance between roller supports and Bending rigidity is the max slope of the bending moment - deflection curve.

They state that the Bending Stiffness is the average value of EI for the plate. However, when I look at the equation for 4-point bending which is as follows.

DeltaX = {(P*a)/24EI}*(3B^2 - 4a^2)

a = distance from support to loading (P)

Solving for EI and assuming ((P/2)*a)/deltax = bending rigidity
one gets;

EI = Bending rigidity * (3B^2 - 4a^2)/24

This is no where near the equation that they have established for the standard.

Would someone please enlighten me on the origin of this equation.

Thanks.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources