Innovative vibration technique as a viable substitute for conventional three point bending fatigue testing

Fatigue lifetime prediction of various materials under three-point-bending is generally limited to the long testing periods consumed and the economic inversion needed develop the test. The use of a vibration technique as a possible alternative to predict fatigue life can be an attractive cost effect option. An innovative vibration fatigue methodology is developed. The procedure uses geometric shape optimization along with finite element analysis to ensure that a specific three-point-bending stress pattern is mimicked in a given region of the test specimen while vibrating in the first resonance. The methodology was compared with three-point-bending tests for two different materials: FR-7140 foam and a sandwich composite. When compared to three-point-bending tests results, the vibration technique showed to be very promising and lifetime predictions fell clearly within the ninety percent confidence levels of the three-point-bending tests.