*MAT_SOIL_CONCRETE

This is Material Type 78. This model permits concrete and soil to be efficiently modeled. See the explanations below.

第78号材料模型，混凝土和土模型。可有效的模拟混凝土和土，详见备注。

卡片 1	1	2	3	4	5	6	7	8
变量	MID	RO	G	K	LCPV	LCYP	LCFP	LCRP
类型	A8	F	F	F	F	F	F	F

卡片 2	1	2	3	4	5	6	7	8
变量	PC	OUT	B	FAIL
类型	F	F	F	F

<p class="postImg">Figure M78-1. Strength reduction factor.</p>

变量	说明
MID	材料编号。必须指定为一个唯一数字或不超过8字符的标签。
RO	质量密度
G	剪切模量
K	体模量
LCPV	Load curve ID for pressure versus volumetric strain. The pressure versus volumetric strain curve is defined in compression only. The sign convention requires that both pressure and compressive strain be defined as positive values where the compressive strain is taken as the negative value of the natural logarithm of the relative volume.
LCYP	Load curve ID for yield versus pressure: GT.0: von Mises stress versus pressure, LT.0: Second stress invariant, J2, versus pressure. This curve must be defined.
LCFP	Load curve ID for plastic strain at which fracture begins versus pressure. This load curve ID must be defined if B > 0.0.
LCRP	Load curve ID for plastic strain at which residual strength is reached versus pressure. This load curve ID must be defined if B > 0.0.
PC	拉伸断裂的截止压力
OUT	塑性应变输出到数据库中选项： EQ.0: 体塑性应变， EQ.1: 偏塑性应变。
B	Residual strength factor after cracking, see Figure M78-1.
FAIL	Flag for failure: EQ.0: no failure, EQ.1: When pressure reaches failure pressure element is eroded, EQ.2: When pressure reaches failure pressure element loses it ability to carry tension.

备注

压力在压缩时为正。 Volumetric strain is defined as the natural log of the relative volume and is positive in compression where the relative volume, V, is the ratio of the current volume to the initial volume. The tabulated data should be given in order of increasing compression. If the pressure drops below the cutoff value specified, it is reset to that value and the deviatoric stress state is eliminated.

<p class="postImg">Figure M78-2. Cracking strain versus pressure.</p>

If the load curve ID (LCYP) is provided as a positive number, the deviatoric, perfectly plastic, pressure dependent, yield function $\phi$, is given as $$ \phi=\sqrt{3J_2} -F(p) =\sigma_y - F(p) $$, where , F(p) is a tabulated function of yield stress versus pressure, and the second invariant, $J_2$, is defined in terms of the deviatoric stress tensor as: $$ J_2=\frac{1}{2} S_{ij} S_{ij} $$assuming that if the ID is given as negative then the yield function becomes:$$\phi=J_2 -F(P) $$being the deviatoric stress tensor.

If cracking is invoked by setting the residual strength factor, B, on card 2 to a value between 0.0 and 1.0, the yield stress is multiplied by a factor f which reduces with plastic strain according to a trilinear law as shown in Figure M78-1.

• b= residual strength factor
• ε1 = plastic stain at which cracking begins.
• ε2 = plastic stain at which residual strength is reached.

ε1 and ε2 are tabulated functions of pressure that are defined by load curves, see Figure M78-2. The values on the curves are pressure versus strain and should be entered in order of increasing pressure. The strain values should always increase monotonically with pressure.

<p class="postImg">Figure M78-3. Yield stress as a function of plastic strain.</p>

By properly defining the load curves, it is possible to obtain the desired strength and ductility over a range of pressures, see Figure M78-3.