MT-1620 al.2002 C)Whack mass with a hammer Force is basically a unit impulse Figure 19.6 Representation of unit impulse force F Force has very high frequencies Response is(structural) waves in spring with no global deflection Paul A Lagace @2001 Unit 19-6
MIT - 16.20 Fall, 2002 C) Whack mass with a hammer ⇒ Force is basically a unit impulse Figure 19.6 Representation of unit impulse force Force has very high frequencies Response is (structural) waves in spring with no global deflection Paul A. Lagace © 2001 Unit 19 - 6
MT-1620 al.2002 Represent this as Figure 19.7 Representation of regions of structural response versus frequency of forcing function Quasi )-Static Dynamics Wave Propagation functon Static What determines division points between regimes? borderline between quasi-static and dynamic is related to natural frequency of structure Depends on structural stiffness structural"characteristic length gives natural frequency of structure borderline between dynamic and waves is related to speed of waves(sound) in material Depends on · modulus density speed Paul A Lagace @2001 Unit 19-7
MIT - 16.20 Fall, 2002 --> Represent this as Figure 19.7 Representation of regions of structural response versus frequency of forcing function (Quasi) - Static Dynamics Wave Propagation Static What determines division points between regimes? --> borderline between quasi-static and dynamic is related to natural frequency of structure. Depends on: • structural stiffness • structural “characteristic length” --> gives natural frequency of structure --> borderline between dynamic and waves is related to speed of waves (sound) in material. Depends on: • modulus • density speed = E ρ Paul A. Lagace © 2001 Unit 19 - 7