11.8.5. Johnson-Holmquist Strength Segmented

Recent studies (Holmquist and Johnson 2002) have showed that gradual softening in the JH2 model has not been supported by available experimental data yet while there are some indications that an early variant of the model, known as JH1, may be more accurate. In the JH1 material model, material strength is described by linear segments and the damage is always applied instantaneously.

Figure 11.6: Johnson-Holmquist Strength Segmented

Note: If the Bulking constant, B is greater than zero then the Johnson-Holmquist model should be used in conjunction with a polynomial equation of state or linear elasticity.

This property can only be applied to solid bodies.

Holmquist, T.J. & Johnson, G.R. (2002). Response of silicon carbide to high velocity impact. Journal of Applied Physics, pp 5858-5866, Vol 91, No. 9, May 1, 2002.

Table 11.8: Input Data

Name	Symbol	Units	Notes
Hugoniot Elastic Limit	σ_HEL	Stress	Elastic limit under dynamic compressive uniaxial strain conditions
Intact Strength Constant S1	S¹	Stress
Intact Strength Constant P1	P¹	Stress
Intact Strength Constant S2	S²	Stress
Intact Strength Constant P2	P²	Stress
Strain Rate Constant C	C	None
Maximum Fracture Strength	S^FMax	Stress
Failed Strength Constant	α	None
Damage Constant	D₁	None
Damage Constant	D₂	Stress
Bulking Constant	B	None
Hydrodynamic Tensile Limit	T	Stress

Custom results variables available for this model:

Name	Description	Solids	Shells	Beams
EFF_PL_STN	Effective Plastic Strain	Yes	No	No
EFF_PL_STN_RATE	Effective Plastic Strain Rate	Yes	No	No
PRESSURE	Pressure	Yes	No	No
DAMAGE	Damage	Yes	No	No
STATUS	Material Status**	Yes	No	No
PRES_BULK	Dilation pressure	Yes	No	No
ENERGY_DAM	Damage energy contributing to bulking	Yes	No	No

**Material status indicators (1 = elastic, 2 = plastic, 3 = bulk failure, 4 = bulk failure, 5 = failed principal direction 1, 6 = failed principal direction 2, 7 = failed principal direction 3)