Experimental study on mechanical behavior of PVB laminated glass under quasi-static and dynamic loadings

Windshield is one of the most important components in automobile to protect pedestrian and passenger, as well as enhance vehicle crashworthiness. The most widely used material for windshield is polyvinyl butyral (PVB) laminated glass. This paper uses both quasi-static compression and dynamic Split Hopkinson Pressure Bar (SHPB) compression experiments under different strain/loading rates to investigate the mechanical behavior of PVB laminated glass. Experimental results show that PVB laminated glass is a strong rate-dependent material with nonlinearity in its constitutive behavior under both quasi-static and dynamic loading circumstances. In quasi-static cases, major failure onset (MFO) strain increases with the loading rate while MFO stress remains the same; however MFO strain and stress will both increase in higher strain rates in dynamic loading. A constitutive model covering all strain/loading rates is then established based on Johnson–Cook model mathematically. Further, crack branching based on crack fractal theory is investigated and an explicit expression describing the crack velocity and number of crack branching is proposed. In addition, dynamic stress intensify factor is calculated to be β≈1.5β≈1.5 and an “impact caused brittleness” effect in PVB laminated material is discussed. Results can provide important experiment data and useful model to further research on vehicle crash safety.