DETERMINATION OF MECHANICAL SPECTRA FROM EXPERIMENTAL RESPONSES

A recursive computer algorithm was developed which generates line spec tra from experimental response functions. The method allows storing in formation on the mechanical properties of polymeric materials in a con venient way. The algorithm also interconverts between relaxation and r etardation spectra. From the spectra, any desired response function ca n then be recovered. The algorithm essentially utilizes the fact that the kernel functions resemble step functions. Slightly different codes are used for each kernel function. The appearance of negative relaxat ion or retardation lines is obviated. Mathematically such lines would be acceptable, and they do not seriously affect reconstruction of resp onses within relaxation or retardation behavior. However, they would s eriously interfere with interconversion between the two types of behav ior, and they would also pose problems in the interpretation of the sp ectra.