1. Measuring and Calculating the Dynamic Response of Simple Structures AOE 3054 E. Nikolaidis

2. Outline 1Introduction 2Analysis of Dynamical Behavior of Structures 3Dynamic Testing of Structures 4Summary/Concluding Remarks

3. 1 Introduction a. Dynamic loading Dynamic means time varying Examples: Aircraft wing-gust loads Offshore platform-waves Car on rough pavement Earthquake loads

5. Terminology Vibration: ?

6. b. Static versus dynamic analysis Static Constant load, response No inertia forces Dynamic ? Inertia forces

8. c. Steps in a dynamical investigation Design Analysis Testing/correction of model Redesign

10. 2 Analysis of Dynamical Behavior of Structures Define ? model Derive ? model Solve for dynamical behavior

16. 3 Dynamical Testing of Structures Why dynamical testing: ?

17. Full-scale structure Reduced scale physical models (use in early design stages)

18. Frequency response function Basic property of linear systems: Sine in-Sine out S cos(  t) ?

19. Beam that can be modeled as a SDOF system

21. Observations  =0 then ? At resonance: Amplitude ratio=Q=AK=1/2  Phase angle= ? For frequencies of excitation much higher than natural frequency the response amplitude is close to zero

22. Example: Large space structures

27. 4 Summary/Concluding Remarks Dynamic loading Steps in dynamical investigation Test Motivation Examples