Materials Testing for Constitutive relations

High suain rate tests have been carried out at both room temperature and 100°C on a Ti6A14V alloy using the torsional split Hopkinson pressure bar. An infrared radiometer has been developed to measure the surface temperature of the specimen during the high speed torsional test. Data have been obtained on the variation of stress with strain and strain rate at shear strain rates from 0.0007s" to 1000s" and on the adiabatic temperature rise during deformation at the higher rates. This data has then been used to determine suitable values for the material constants in a constitutive relauon of the form proposed by Zrrilli-Armstrong for bcc materials for application to the hcp titanium alloy used in the present investigation. Resume : Des experiences B grandes vitesses de deiormation ont Ote et'fectuees temperature amhiante et i 100°C sur I'alliage Ti6A14V. en utilisa~lt des harres d'Hopkinson en torsion. Un radiom2ue infrarouge a 216 dOveloppO pour mesurer la temperature de surface de l'6chanr1llon pendant le test. Des donnCes ont 612 ohtrnues sur la variation de la cqnui~intc -1 en fonction de la vitesse de derormation ct de la deformation, A des vitesses de glissement de 0.0007 s 1000 s'l er sur I'elevation de temperature aux plus hautcs vitcsses. Ces donnecs ont ensuitc Ote utilisees pour determiner le param2tres du materiau dans le modkle de Zerilli-Armstrong, pour les mat2riaux de type cuhique centre et ceux de type hexagonaux commr les alliages de titane.