I am characterizing PMMA mechanical properties with DMA; why does the E' increases as I increase pre-stress in 3pt bending?

the sample is 2*5*50mm and the span is 25mm 2.E' changes from 3.3GPa to 4.9 GPa when I increase the value of pre-stress from 30 gm to 350gm 3.strain amplitude: 0.0001 4.frequency: 1 Hz

09 December 2015 9,401 9 View