Flexural rigidity, what does high flexural rigidity mean?

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SUMMARY

The discussion centers on the concept of flexural rigidity, defined as the product of the modulus of elasticity (E) and the moment of inertia (I) of a beam, represented as EI. A higher EI value, such as 2.1E+10 N.mm^5, indicates increased stiffness, making the beam harder to bend. However, the overall stiffness also depends on the beam's length and end conditions. The participants clarify the units of EI and discuss the relationship between moment (M), curvature (K), and deflection in the context of a simply supported beam under load.

PREREQUISITES
  • Understanding of flexural rigidity and its components (E and I)
  • Familiarity with beam theory and deflection calculations
  • Knowledge of units in mechanics, specifically N/mm^2 and mm^4
  • Basic principles of structural engineering and load applications
NEXT STEPS
  • Research the implications of varying end conditions on beam stiffness
  • Study the relationship between moment, curvature, and deflection in beam theory
  • Explore advanced topics in structural analysis, such as finite element methods
  • Investigate experimental methods for measuring flexural rigidity in beams
USEFUL FOR

Structural engineers, civil engineering students, and anyone involved in the design and analysis of beam structures will benefit from this discussion on flexural rigidity and its practical implications.

chris_usyd
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Homework Statement


simply put, i got 2.1E+10 N.mm^5 for my steel beam experiment?
but i am wonder, what conclusions can i make?

2. The attempt at a solution
from online resouce, flexural rigidity is defined as the force couple required to bend a rigid structure to a unit curvature.
so , the higher EI, the better? :redface:
 
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Not necessarily better, but the higher the EI, the stiffer the beam, and the harder it will be to bend. Actually, definition not withstanding, the stiffness depends not only on EI, but also the length of the beam and its end conditions. What was your experiment? The units don't make sense.
 
units?
yeah, i am confused as well.
isnt N.mm^2? since E(N/mm^2) I(mm^4)
the experiment is to examining the stiffness of a steel beam through 2 types of deformation-deflection and curvature..
now i am writing the discussion part, but not many things to be mentioned.
 
but i got different values..
so also need some comparisons.
 
by the way, jay, "what are the assumptions in calculating EI that may not be strictly true??"
i can't even find one
you know, by deflection, i plotted the mid-span moment(M) against the curvature(K). because M=EIk, the slope is the value of EI.
i think it is perfect..
 
EI has units (N/mm^2)(mm^4) = N*mm^2

Curvature k is EI/M and has units of mm.

I am not surewhat you are measuring in your experiment...deflection, stress, curvature?...and what you are trying to calculate.

If you have a simply supported beam of length L with a concentrated load P at L/2, then M_max = PL/4 at midpoint, and max deflection is PL^3/48EI at that point, in theory.
 

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