Dynamic mechanical spectroscopy of sheet molding compound as a function of offset stress

It has been determined that preload and cyclic amplitude have significant effect on the results of dynamic mechanical measurements of tan δ. To illustrate these effects on composites, a particular type of sheet molding compound (SMC‐R50) was used in this study. In addition to the effects of preload and cycle amplitude, the effects of frequency, and creep prior to dynamic mechanical testing were also investigated.