Abstract

Dynamic testing is very useful in the design and development of products and systems. Although designers employ most powerful analysis tools, using the most elaborate electronic computers, actual testing is required in order to ensure the proper functioning of the designed system. For the structures that are extremely small such as the Micro Electromechanical Systems (MEMS) or that are very large such as civil and aerospace structures complex dynamic tests can be carried out on a replica of the system, called the model , made to larger or smaller scale, respectively, for reasons of economy, convenience and saving in time. Similitude theory is employed to develop the necessary similarity conditions (scaling laws) for dynamic testing of scaled structures. Scaling laws provide relationship between a full-scale structure and its small scale model, and can be used to predict the response of the prototype by performing dynamic testing on inexpensive model conveniently. Such scaled models have been extensively used in wind tunnel testing of large structures such as automobiles, buildings and aircrafts structures. The difficulty of making completely similar small scale models often leads to certain types of relaxations and distortions from exact duplication of the prototype (partial similarity). Both complete and partial similarities are discussed. These scaling laws are then validated both by carrying out finite element analysis using ANSYS 7.1, and by performing experiments in the laboratory for a simple structures. The above methodology has also been applied to the design validation of a shipboard monitor console. The console is required to isolate the monitor from the shock and vibration inputs and ensure its proper functioning. The shipboard console and its scale model have been investigated for their dynamic response subjected to sinusoidal and shock loads and a good correlation has been found between the prototype and the model.