Characterising the fracture toughness of polymers at moderately high rates of loading with the use of instrumented tensile impact testing

The more common use of instrumentation in impact testing opened up the possibility to apply fracture mechanics testing methods to polymers at moderately high impact rates. Tensile impact testing offers some advantages over the more common three-point bending and compact tension geometries. Most importantly the dynamic effects encountered at (moderately) high impact rates are less significant due to inherent damping within the specimens. Consequently, the fracture toughness can be determined directly from the force signal without having to employ more sophisticated instrumentation or more elaborate analysis. Despite some unresolved issues the first results on fracture mechanics based tensile impact testing are promising: the toughness values found are comparable to those found using other loading geometries and show less scatter.