In any wave propagation code, such as LS-DYNA, which belongs to a family of ‘Hydro’ codes, bulk viscosity is essential to treat shocks. Smooth initial data can lead into shock discontinuities and if left untreated can result in severe instabilities. LS-DYNA has the capability (performed by default) to automatically detect the shocks and treat them [...]
Archive for January, 2007
Bulk Viscosity for Shells and Solids in LS-DYNA
Published by January 26th, 2007 in LS-DYNA Bytes and LS-DYNA Elements. 4 CommentsLimitations of Using LCSR for Strain-Rate Inclusion in MAT_024
Published by January 26th, 2007 in LS-DYNA Curves and LS-DYNA Materials. 1 CommentThe widely popular material model *MAT_PIECEWISE_LINEAR_PLASTICITY (MAT_024) supports various methods to include the strain-rate effects. One of the methods is the scaling of the quasi-static stress-strain curves using a load-curve, LCSR, that defines a scale-factor as a function of strain-rate. This method works by first finding the yield-stress, SIG_QUASI_STATIC, as a function of the effective [...]
Modeling Loading and Unloading Behavior in Seatbelt Materials
Published by January 24th, 2007 in LS-DYNA Materials. 0 CommentsSeatbelt constitutive model, invoked by using *MAT_SEATBELT, in LS-DYNA provides features to model the loading and unloading characteristics from a uni-axial test. Parameter LLCID provides ability to model the loading curve which allows the definition of force as a function of engineering strain. Parameter ULCID, provides ability to model the unloading curve again allowing the [...]
Identifying Necking in Metals and Plastics
Published by January 16th, 2007 in LS-DYNA Materials. 4 CommentsWhen characterizing materials such as Metals and Plastics in LS-DYNA, most constitutive models provide a yield criteria that accounts for a 3D state of stress which reduces to a uniaxial yield stress in 1D. This allows us to directly input the true stress-strain curve from a one-dimensional state of stress testing such as in uniaxial [...]
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