An apparatus for the measurement of damping properties of materials under biaxial stress conditions utilizes three electro- hydraulic servo-systems to apply fluctuating internal, external, and axial pressures to a hollow cylindrical specimen. The ar rangement imposes difficulties with respect to specimen loading, system interactions, stability and control. An analog simulation was conducted as a direct step in the design procedure in order to prove the feasibility of the apparatus, to provide guidance in the choice of design parameters, and to investigate system operating conditions and procedures.
The simulation and its use with respect to both design and opera tion of the apparatus are described. In the simulation, account is taken of servo-valve characteristics, fluid leakage paths, specimen deflection, chamber volumes, and fluid compressibil ity. The (successful) performance of the apparatus as built is also described, and the similarity of simulated and actual behaviour is apparent.
