Dynamic mechanical properties of polyurethane elastomers using a nonmetallic Hopkinson bar

✍ Scribed by S. Rao; V. P. W. Shim; S. E. Quah

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 304 KB
• Volume: 66
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19971024)66:4<619::aid-app2>3.0.co;2-v

✦ Synopsis

A modified split Hopkinson-bar apparatus, in which the striker and input/ output bars are made of polycarbonate instead of metal, was used to study three typical examples of a high-density flexible polyurethane elastomer (PORON) in sheet form. This variation of the device reduces a mismatch in impedance between the input/output bars and the specimen, thus allowing the stress in the specimen to reach a uniform state before significant engineering strain is induced. Dynamic compressive stressstrain curves were obtained from the measured incident, transmitted, and reflected waves. This article presents the behavior of these foams as a function of strain rate; for PORON 4701-05-20125-1637 under strain rates of 2.67 1 10 03 s 01 to 4500 s 01 , the stress-strain response can be described by a function comprising a rate-dependent modulus and a strain-dependent factor, while for PORON 4701-01-30125-1604 and 4701-12-30062-1604, only loading at high strain rates yields similar characteristics. Empirical equations were derived to characterize these mechanical properties; in addition, characteristics relating to energy-absorption capability as well as deformation under approximately constant stress were also studied.