Research activities E Nikolaidis B Ramaswamy B Dheenadayalan

Research activities E. Nikolaidis B. Ramaswamy B. Dheenadayalan A. Keerti S. Mathew P. Soundappan D. Tiwary Vibration and Reliability Lab Friday, April 20, 2001 1

Overview 1. Design under uncertainty 3. Knowledge-based design tools 2. Structural dynamics 2

Design under uncertainty Noise level (db) Design concept 1 Design concept 2 Design concept 3 Cost ($) 3

Profit is uncertain and depends on selection of design concept Probability density of profit Loss Profit ($) 0 Which design is better ? 4

Goals • Study and understand advantages and limitations of methods for modeling uncertainty (classical probability, Bayesian probability, fuzzy sets, imprecise probabilities) • Study methods for modeling a decision-maker’s preferences and attitude toward risk • Address issues of lack of data and high computational cost • Develop tools for making design decisions under uncertainty by combining the above methods 5

2. Structural Dynamics; Modeling and suppressing internal resonances in vibration isolators Front of the car 6

Transmissibility of real isolator System resonance, n Transmissibility Isolator Resonances Actual 1 Ideal 1 / n 7

Using DVA’s to suppress internal resonances 8

Knowledge-based design tools; considering details upfront in design Global Vehicle Model Global design variables Load and stiffness requirements for components Global Optimizer Optimal safety factor of components Local models 9

Traditional design optimization versus local/global optimization infeasible 100 84 feasible 85 10