Cantilever beam (statically indeterminate)

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Discussion Overview

The discussion revolves around the analysis of a statically indeterminate cantilever beam subjected to a specific loading case. Participants are exploring methods to calculate the maximum deflection at the loading point and the maximum reaction values at the supports, focusing on the application of equilibrium equations and superposition principles.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • Durka presents a bending moment equation for the cantilever beam and seeks assistance with calculating deflection and reactions.
  • Hotvette suggests using the principle of superposition to analyze the loading case by treating it as the sum of two independent loadings.
  • Durka expresses difficulty in proceeding due to a lack of equilibrium equations and seeks clarification on how to replace variables in these equations.
  • Another participant emphasizes that equilibrium equations alone are insufficient for solving the problem and reiterates the utility of superposition for calculating deflection.

Areas of Agreement / Disagreement

Participants generally agree on the need to use superposition for the analysis, but there is no consensus on the specific equilibrium equations or methods to apply for solving the problem.

Contextual Notes

There are unresolved aspects regarding the specific equilibrium equations needed and the assumptions underlying the application of superposition in this context.

durka
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hello everyone,
i have a small problem in calculating a particular loading case of a cantilever beam which is shown on the attached image.

i have found many loading cases of cantilever beams which i am able to solve, however for this one i couldn't find anything unfortunately.

the bending moment equation which i have written is:
M(x)= -Mw+Rwx-R[x-0.4] which i hope is correct



determined needs to be:
a) The maximum deflection at the loading point (695N at 0.4)
b)The maximum values of the reactions at the supports.

for any hints and advices i will be grateful

best regards
durka
 

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The answer is superposition. You know (or can derive) the equation(s) for a cantilever beam (w/o the 2nd support) with a point load. Consider this case to be the sum of two independent loadings, the 2nd of which is at the end of the beam in the upward direction (instead of the support), with a physical constraint that the net displacement of the end of the beam is zero.
 
hello hotvette,
thanks for your quick answer.

i have solved a part of the question, but i can not continue because i don't have the equilibrium equations.

i came to the point:
EI DELTA=Mw0.08-Rw0.0106+Rp0.0106-Rp0.032

i don't get any further because the equilibrium equations that i have used don't make any sense so i canot solve it.

i know that i must replace either Rp or Rw and Mw from the equilibrium equations
 
You cannot solve this from the equilibrium equations alone.

If you follow Hotvette's suggestion an use superposition, you should be able to calculate the cantilever deflection from the load acting without the roller support and equate it to the deflection from the roller support reaction acting without the load.
 

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