Mechanical characterisation of a viscoplastic material sensitive to hydrostatic pressure

Abstract

International audienceThe present paper deals with the characterisation of the static mechanical behaviour of an energetic material all along its lifespan. The material behaviour is viscoplastic, damageable and sensitive to hydrostatic pressure. For such materials, existing models have generally been developed in the framework of transient dynamic behaviour. These models are not suitable for a static study. Therefore a specific experimental protocol and an associated model are developed. Characterisation is derived from both uniaxial compressive, tensile tests and tri-axial tests. Plastic behaviour is described by means of a parabolic yield criterion and a new hardening law. Non-associated plastic flow rule and isotropic damage complete the model. The performance of the model is illustrated through the simulation of various loading paths

Quasistatic mechanical behavior of HMX- and TATB-based plastic-bonded explosives

“…Consequently, for each cycle, the secant modulus between the end of the relaxation and the end of the recovery is elastic (green lines in Figure 16). This assumption, made in previous papers (Gratton et al, 2009; Le et al, 2010; Picart et al, 2014) on M1, is commonly used for estimating the damage evolution of concrete (Benouniche, 1979;Gotuwka, 1999). Tangent and secant moduli are compared in Figure 16.…”

“…Since 2000, the CEA and the Gabriel LaMé Laboratory have undertaken an extensive experimental campaign to characterize the various behavioral features of the material M1. This database includes monotonic and cyclic compressions at 20°C and under atmospheric pressure, for four strain rates from 10 -6 s -1 to 10 -3 s -1 ; monotonic and cyclic compressions at 20°C under 5 and 10 MPa, at 10 -5 s -1 ; monotonic and cyclic tension tests at 0°C, 20°C, 35°C and 50°C under atmospheric pressure, at 10 -5 s -1 (Benelfellah, 2013;Caliez et al, 2014;Gratton et al, 2009;Le, 2007;Le et al, 2010;Picart and Brigolle, 2010;Rja Fi Allah, 2006); cyclic compressions at 0°C, 35°C and 50°C under atmospheric pressure, at 10 -5 s -1 (Le, 2007); heterogeneous tests such as the Brazilian test, biaxial tension (plate bending), channel-die test, Iosipescu test and three-point bending, at 20°C under atmospheric pressure, at a strain rate of about 10 -5 s -1 (Benelfellah, 2013;Le, 2007;Picart and Pompon, 2016); alternate tension-compression and compression-tension at 20°C under atmospheric pressure, at 10 -5 s -1 (Benelfellah, 2013; Picart and Brigolle, 2010); as well as a dynamic mechanical analysis (DMA) campaign (Picart and Brigolle, 2010). For each uniaxial or triaxial test of these papers, the longitudinal and transversal strains are given.…”

“…Since this approach only enables simulation of monotonic tests, we refer the reader to the original paper for its description. A second model was proposed by Gratton et al (2009), including an elasto-viscoplastic law with isotropic damage and pressure-dependent viscoplastic behavior. This model was later completed to describe the viscoelasticity visible during load-unload loops.…”