How Does Deformation Measure Change with Large Rigid Body Rotations?

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SUMMARY

The discussion centers on the concept of deformation measures in the context of large rigid body rotations. It is established that a deformation represented by a 3x3 matrix, specifically cos(a), 0, 0; 0, cos(a), 0; 0, 0, 0, is not invariant under such rotations. This is due to the fact that the deformation is limited to the x and y directions, leading to different matrix representations when axes are interchanged, such as swapping x and z. Thus, the measure fails to maintain consistency across large rotations.

PREREQUISITES
  • Understanding of 3x3 matrices and their properties
  • Familiarity with rigid body rotation concepts
  • Knowledge of deformation measures in mechanics
  • Basic trigonometry, particularly the cosine function
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  • Study the principles of rigid body dynamics and rotation matrices
  • Explore the concept of invariance in deformation measures
  • Learn about the implications of axis swapping in matrix transformations
  • Investigate advanced topics in continuum mechanics related to deformation
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Students and professionals in mechanical engineering, physics, and applied mathematics who are studying the effects of rigid body rotations on deformation measures.

sara_87
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Homework Statement



What does it mean when a measure of defomation is 'not invariant with respect to large rotations of the body as rigid'?
i found that a measure of deformation is a 3x3 matrix:
cos(a),0,0
0,cos(a),0
0,0,0
where a is a constant
so why does this prove that this measure is 'not invariant with respect to large rotations of the body as rigid'?

Homework Equations





The Attempt at a Solution

 
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sara_87 said:
i found that a measure of deformation is a 3x3 matrix:
cos(a),0,0
0,cos(a),0
0,0,0
where a is a constant
so why does this prove that this measure is 'not invariant with respect to large rotations of the body as rigid'?

Hi sara_87! :smile:

I think it means that the deformation is only in the x and y directions, so if for example you swap round the x and z directions, the matrix will be different.
 

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