High rate mechanical properties of Dyneema in compression

Abstract. The dynamic compressive properties of Dyneema have been investigated using a drop-weight machine. The mechanical behaviour was monitored using high-speed photography and aforce transducer. There was considerable variation in behaviour shot-to-shot, but all the specimensof this material were observed to shatter in this apparatus. Stress-time plots showed multiple fail-ures on a timescale of approximately 0.2 ms interval. 1. INTRODUCTIONDyneema is the registered trademark of a self-reinforced polyethylene (manufactured by DSM)which is showing great promise as a replacement for brittle-fibre-reinforced epoxies in variousdynamic applications [1–3]. As part of an investigation of its high rate mechanical properties, wehave measured the impact response of this material in compression using a dropweight [4].2. EXPERIMENTALDropweights are used in many industrial settings as a conceptually simple impact test. Their mainadvantage over other techniques of similar strain rates is their ability to apply a large force for acomparatively long period of time. Their main disadvantage is that their output signal usually haslarge oscillations due to ringing within the dropweight or the associated force transducer [5, 6].In the work reported here, a weight of mass 6.414 kg is dropped from a height of about 1.25 montoaforce transducer (Figure 1).The massis guidedtothe target bytwo rodson either side. Theimpact speed is about 5 m s