Influence of Orientation on the Dynamic Compression Properties of Poly(methyl methacrylate)

Poly(methyl methacrylate) with biaxial stretching orientation (BO-PMMA) has superior mechanical properties compared to casting (unoriented, UO-PMMA), and is therefore widely used in the field of transparent structures. To investigate the effect of orientation on the dynamic compression properties of PMMA and establish a constitutive model applicable to BO-PMMA at different strain rates and service temperatures, this study conducted compression experiments on BO-PMMA at relatively low strain rates (1, 10, 100 s^-1) and high strain rates (2000, 3000, 4000 s^-1), as well as at room temperature (RT), 80 °C, and -40 °C. Through the quantitative comparison of the stress-strain curves of BO-PMMA and UO-PMMA, the influence mechanism of orientation on compressive mechanical behavior was elucidated. Based on the experimental results, the parameters of the DSGZ (Duan-Saigal-Greif-Zimmerman) phenomenological constitutive equation were fitted. Using this model, the PMMA with different orientations was numerically simulated and analyzed. The results indicated that increasing the strain rate or decreasing the temperature will increase the yield stress of PMMA. In particular, it was found that BO-PMMA performs more significant strain rate and low-temperature sensitivity than UO-PMMA. Meanwhile, the established constitutive model can effectively describe the dynamic compressive mechanical behavior of BO-PMMA and UO-PMMA at different strain rates and temperatures. Accordingly, it has a certain engineering application guidance value.