MT-1620 al.2002 General Rules for discrete systems Can find various modes(without amplitudes) by considering combinations of positive and negative(relative)motion However, be careful of (-1)factor across entire mode For example in two degree- of-freedom case +十 same mode same mode The more reversals" in direction, the higher the mode(and the frequency It is harder to excite higher modes This can be better illustrated by considering the vibration of a beam. So look at Representation of a Beam as a Discrete Mass System Paul A Lagace @2001 Unit 22-10MIT - 16.20 Fall, 2002 General Rules for discrete systems: • Can find various modes (without amplitudes) by considering combinations of positive and negative (relative) motion. However, be careful of (-1) factor across entire mode. For example, in two degree-of-freedom case + + + - same mode same mode - - - + • The more “reversals” in direction, the higher the mode (and the frequency) • It is harder to excite higher modes This can be better illustrated by considering the vibration of a beam. So look at: Representation of a Beam as a Discrete Mass System Paul A. Lagace © 2001 Unit 22 - 10