The Johnson-Holmquist series of ceramic models are currently being used in a broader program aimed at computational optimization of composite lightweight armor vehicles. Kaufmann et al. have used the JH-2 material model in LS-Dyna to simulate ballistic impacts on armour-grade alumina with an aluminum backing. The implementation and validation of the Johnson-Holmquist (JH-2) constitutive model in LS-Dyna (Version 970), based on the constitutive equations proposed by Johnson and Holmquist is presented in the paper. Within this model, the initiation and progression of cracking through the material is tracked with a representative damage variable. The constitutive model expresses the material strength as a function of pressure and damage, while incorporating material bulking due to damage. The current implementation of JH-2 model in LS-Dyna accurately reproduces the published data for simple single element validation cases. A simple sample calculation of a steel sphere impacting a silica-based glass plate was presented to demonstrate application of this constitutive model to an impact simulation. These results demonstrate the experimentally observed phenomena of damage evolution, fracture propagation, and spall damage resulting from reflected compression waves at a free surface. The JH-2 model in LS-Dyna has also been used to successfully simulate the ballistic impact of 12.7 mm armour-piercing projectiles on supported alumina tiles. The numerical results, based on the depth of penetration of the projectile in the aluminum backing, were in good agreement with the experimentally measured values.
Implementation and validation of the Johnson-Holmquist ceramic material model in LS-Dyna
Implementierung und Validierung des Johnson-Holmquist Kermikwerkstoffmodells in LS-Dyna
2003
13 Seiten, 5 Bilder, 2 Tabellen, 13 Quellen
Aufsatz (Konferenz)
Englisch
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