EOMs for T Shaped Pendulum with Non-Conservative Force

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Discussion Overview

The discussion centers on deriving the equations of motion (EOMs) for a "T" shaped pendulum system that includes non-conservative forces. The focus is on a two-dimensional approximation of the system, which consists of a base mass constrained to move in the x-direction and a top mass that can rotate. The inquiry involves the application of virtual work principles and the treatment of forces in the system.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • The base mass is connected to the ground by a linear spring, which aims to restore it to the x = 0 position, while friction is ignored.
  • The top mass, representing the "T" shaped pendulum, rotates about the center of the base coordinate system, influenced by a torsional spring that seeks to restore it to the vertical position.
  • The poster has chosen generalized coordinates of x (for the base mass) and theta (for the pendulum's rotation from horizontal).
  • The poster questions whether their application of virtual work is correct and if there is a need to consider moment-work in their derivations.

Areas of Agreement / Disagreement

The discussion does not indicate any consensus or resolution, as the main question regarding the virtual work and moment-work remains open for further input and clarification.

Contextual Notes

The discussion may be limited by assumptions regarding the simplifications made in the model, the neglect of friction, and the specific definitions of the forces involved in the system.

bcarlson
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EOMs for "T" Shaped Pendulum with Non-Conservative Force

I have a set of equations of motion I'm trying to derive. This problem represents a 2-d approximation of the real system that I'm trying to derive equations of motion for modeling purposes.

There is a base mass and a top mass.

The base mass is constrained to move only in the x direction and is connected by a linear spring to ground which is meant to produce forces that restore the mass to the x = 0 position. Friction is ignored.

The top mass designated (the "T" shaped pendulum) can rotate about the point at the center of the base coordinate system. A torsional spring is operating on the pendulum to produce forces that restore it to the vertical position.

I've chosen my generalized coordinates to be x (corresponding to x-base) and theta (rotation of pendulum from horizontal).

I will include my derivations in reply to this post but my main question is whether I did the virtual work properly? Do I need to for any sort of moment-work?
 
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System Figures
 

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