The stress error associated with a four-point, fixed-roller flexure fixture was analyzed under three different cyclic loading forms: triangular, sinusoidal and square wave forms. The fixed-roller fixture could not reproduce the exact cyclic wave form in response to the input form, resulting in an undesirable hysteresis in the load-strain curves. The hysteresis represents the loading and unloading stress errors, which gives rise to deviations in wave shape as well as load (R-) ratio.
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