4.20 PIPE20 Plastic Straight Pipe

The element has plastic, creep and swelling capabilities. If these effects are not needed, the elastic pipe element, PIPE16, may be used. An option is available for printing the forces and moments acting on the element in the element coordinate system. See Section 14.20 in the ANSYS Theory Reference for more details about this element. A plastic curved pipe element (PIPE60) is described in Section 4.60.

Figure 4.20-1 PIPE20 Plastic Straight Pipe

4.20.1 Input Data

The element X-axis is oriented from node I toward node J. The element y-axis is automatically calculated to be parallel to the global X-Y plane. Several orientations are shown in Figure 4.20-1. For the case where the element is parallel to the global Z-axis (or within a 0.01 percent slope of it), the element Y-axis is oriented parallel to the global Y-axis (as shown). Input and output locations around the pipe circumference identified as being at 0° are located along the element Y-axis, and similarly 90° is along the element Z-axis.

Element loads are described in Section 2.7. Pressures may be input as surface loads on the element faces as shown by the circled numbers on Figure 4.20-1. Internal pressure (PINT) and external pressure (POUT) are input as positive values. The transverse pressures (PX, PY, and PZ) may represent wind or drag loads (per unit length of the pipe) and are defined in the global Cartesian directions. Positive transverse pressures act in the positive coordinate directions. See Section 14.16.7 of the ANSYS Theory Reference for details.

Temperatures and fluences may be input as element body loads at the nodes. The first temperature (TAVG at node I) defaults to TUNIF. If all temperatures after the first are unspecified, they default to the first. If all temperatures at node I are input, and all temperatures at node J are unspecified, the node J temperatures default to the corresponding node I temperatures. For any other pattern of input temperatures, unspecified temperatures default to TUNIF. Similar defaults occurs for fluence except that zero is used instead of TUNIF.

A summary of the element input is given in Table 4.20-1. Section 2.1 gives a general description of element input.

Table 4.20-1 PIPE20 Input Summary

Element Name	PIPE20
Nodes	I, J (node I defines end 1)
Degrees of Freedom	UX, UY, UZ, ROTX, ROTY, ROTZ
Real Constants	OD, TKWALL, SIFI, SIFJ (SIFI, SIFJ used only if KEYOPT (2) = 4)
Material Properties	EX, ALPX, PRXY or NUXY, DENS, GXY, DAMP
Surface Loads	Pressures: 1-PINT, 2-PX, 3-PY, 4-PZ, 5-POUT
Body Loads	Temperatures: TAVG ( I ), T90 ( I ), T180 ( I ), TAVG ( J ), T90 ( J ), T180 ( J ) Fluences: FLAVG ( I ), FL90 ( I ), FL180 ( I ), FLAVG ( J ), FL90 ( J ), FL180 ( J )
Special Features	Plasticity, Creep, Swelling, Stress stiffening, Large deflection, Large strain, Birth and death.
KEYOPT(2)	0 - No stress intensification factors 4 - Include stress intensification factors at nodes I and J as input with real constants
KEYOPT(6)	0 - No printout of member forces or moments 1 - Print member forces and moments in the element coordinate system

4.20.2 Output Data

• nodal displacements included in the overall nodal solution
• additional element output as shown in Table 4.20-2

Figure 4.20-2 PIPE20 Stress Output

The following notation is used in Table 4.20-2:

A colon (:) in the Name column indicates the item can be accessed by the Component Name method [ETABLE, ESOL] (see Section 2.2.2). The O and R columns indicate the availability of the items in the file Jobname.OUT (O) or in the results file (R), a Y indicates that the item is always available, a number refers to a table footnote which describes when the item is conditionally available, and a - indicates that the item is not available.

Table 4.20-2 PIPE20 Element Output Definitions

Name	Definition	O	R
EL	Element number	Y	Y
NODES	Nodes - I, J	Y	Y
MAT	Material number	Y	Y
VOLU:	Volume	-	Y
CENT: X, Y, Z	Center location XC, YC, ZC	-	Y
TEMP	Temperatures TAVG(I), T90(I), T180(I), TAVG(J), T90(J), T180(J)	Y	Y
FLUEN	Fluences FLAVG(I), FL90(I), FL180(I), FLAVG(J), FL90(J), FL180(J)	Y	Y
PRES	Pressures PINT, PX, PY, PZ, POUT	Y	Y
MFOR(X, Y, Z)	Member forces for nodes I and J (in the element coordinate system)	1	1
MMOM(X, Y, Z)	Member moments for nodes I and J (in the element coordinate system)	1	1
SDIR	Direct (axial) stress	-	2
SBEND	Maximum bending stress at outer surface	-	2
ST	Shear stress at outer surface due to torsion	-	2
SSF	Shear stress due to shear force	-	2
S1MX, S3MN,	Maximum principal stress, minimum principal stress, maximum	2	2
SINTMX, SEQVMX	Maximum stress intensity, maximum equivalent stress all at the outer surface (based on SDIR, SBEND, ST, SSF but also accounting for the values of S1, S3, SINT, SEQV given below)	2	2
S(AXL, RAD, H, XH)	Axial, radial, hoop, and shear stresses	3	3
S(1, 3, INT, EQV)	Maximum principal stress, minimum principal stress, stress intensity, equivalent stress	3	3
EPEL(AXL, RAD, H, XH)	Axial, radial, hoop, and shear strains	3	3
EPTH(AXL, RAD, H)	Axial, radial, and hoop thermal strain	3	3
EPPL(AXL, RAD, H, XH)	Axial, radial, hoop, and shear plastic strains	3	3
EPCR(AXL, RAD, H, XH)	Axial, radial, hoop, and shear creep strains	3	3
SRAT	Ratio of trial stress to stress on yield surface	3	3
EPEQ	Equivalent plastic strain	3	3
HPRES	Hydrostatic pressure	-	3
SEPL	Equivalent stress from stress-strain curve	3	3
EPSWAXL	Axial swelling strain	3	3

1. If KEYOPT(6)=1

2. Initial elastic solution only before yield

3. The item repeats for THETA=0,45,90,135,180,225,270,315° at node I, then at node J, all at the mid-thickness of the wall

The following tables list output available through the ETABLE command using the Sequence Number method. See Chapter 5 of the ANSYS Basic Analysis Procedures Guide and Section 2.2.2.2 of this manual for more information. The following notation is used in Tables 4.20-3 through 4.20-3b:

Name - output quantity as defined in the Table 4.20-2

Item - predetermined Item label for ETABLE command

E - sequence number for single-valued or constant element data

I,J - sequence number for data at nodes I and J

Node I
Name	Item	E	Circumferential Location
			0°	45°	90°	135°	180°	225°	270°	315°
SAXL	LS	-	1	5	9	13	17	21	25	29
SRAD	LS	-	2	6	10	14	18	22	26	30
SH	LS	-	3	7	11	15	19	23	27	31
SXH	LS	-	4	8	12	16	20	24	28	32
EPELAXL	LEPEL	-	1	5	9	13	17	21	25	29
EPELRAD	LEPEL	-	2	6	10	14	18	22	26	30
EPELH	LEPEL	-	3	7	11	15	19	23	27	31
EPELXH	LEPEL	-	4	8	12	16	20	24	28	32
EPTHAXL	LEPTH	-	1	6	11	16	21	26	31	36
EPTHRAD	LEPTH	-	2	7	12	17	22	27	32	37
EPTHH	LEPTH	-	3	8	13	18	23	28	33	38
EPSWAXL	LEPTH	-	5	10	15	20	25	30	35	40
EPPLAXL	LEPPL	-	1	5	9	13	17	21	25	29
EPPLRAD	LEPPL	-	2	6	10	14	18	22	26	30
EPPLH	LEPPL	-	3	7	11	15	19	23	27	31
EPPLXH	LEPPL	-	4	8	12	16	20	24	28	32
EPCRAXL	LEPCR	-	1	5	9	13	17	21	25	29
EPCRRAD	LEPCR	-	2	6	10	14	18	22	26	30
EPCRH	LEPCR	-	3	7	11	15	19	23	27	31
EPCRXH	LEPCR	-	4	8	12	16	20	24	28	32
SEPL	NLIN	-	1	5	9	13	17	21	25	29
SRAT	NLIN	-	2	6	10	14	18	22	26	30
HPRES	NLIN	-	3	7	11	15	19	23	27	31
EPEQ	NLIN	-	4	8	12	16	20	24	28	32
S1	NMISC	-	1	6	11	16	21	26	31	36
S3	NMISC	-	3	8	13	18	23	28	33	38
SINT	NMISC	-	4	9	14	19	24	29	34	39
SEQV	NMISC	-	5	10	15	20	25	30	35	40
SBEND	NMISC	81	-	-	-	-	-	-	-	-
SSF	NMISC	82	-	-	-	-	-	-	-	-
FOUT	NMISC	-	88	-	85	-	86	-	87	-
FIN	NMISC	-	92	-	89	-	90	-	91	-
TOUT	LBFE	-	4	-	1	-	2	-	3	-
TIN	LBFE	-	8	-	5	-	6	-	7	-
MFORX	SMISC	1	-	-	-	-	-	-	-	-
MFORY	SMISC	2	-	-	-	-	-	-	-	-
MFORZ	SMISC	3	-	-	-	-	-	-	-	-
MMOMX	SMISC	4	-	-	-	-	-	-	-	-
MMOMY	SMISC	5	-	-	-	-	-	-	-	-
MMOMZ	SMISC	6	-	-	-	-	-	-	-	-
SDIR	SMISC	13	-	-	-	-	-	-	-	-
ST	SMISC	14	-	-	-	-	-	-	-	-

Table 4.20-3a PIPE20 Item and Sequence Numbers for the ETABLE and ESOL Commands

Node J
Name	Item	E	Circumferential Location
			0°	45°	90°	135°	180°	225°	270°	315°
SAXL	LS	-	33	37	41	45	49	53	57	61
SRAD	LS	-	34	38	42	46	50	54	58	62
SH	LS	-	35	39	43	47	51	55	59	63
SXH	LS	-	36	40	44	48	52	56	60	64
EPELAXL	LEPEL	-	33	37	41	45	49	53	57	61
EPELRAD	LEPEL	-	34	38	42	46	50	54	58	62
EPELH	LEPEL	-	35	39	43	47	51	55	59	63
EPELXH	LEPEL	-	36	40	44	48	52	56	60	64
EPTHAXL	LEPTH	-	41	46	51	56	61	66	71	76
EPTHRAD	LEPTH	-	42	47	52	57	62	67	72	77
EPTHH	LEPTH	-	43	48	53	58	63	68	73	78
EPSWAXL	LEPTH	-	45	50	55	60	65	70	75	80
EPPLAXL	LEPPL	-	33	37	41	45	49	53	57	61
EPPLRAD	LEPPL	-	34	38	42	46	50	54	58	62
EPPLH	LEPPL	-	35	39	43	47	51	55	59	63
EPPLXH	LEPPL	-	36	40	44	48	52	56	60	64
EPCRAXL	LEPCR	-	33	37	41	45	49	53	57	61
EPCRRAD	LEPCR	-	34	38	42	46	50	54	58	62
EPCRH	LEPCR	-	35	39	43	47	51	55	59	63
EPCRXH	LEPCR	-	36	40	44	48	52	56	60	64
SEPL	NLIN	-	33	37	41	45	49	53	57	61
SRAT	NLIN	-	34	38	42	46	50	54	58	62
HPRES	NLIN	-	35	39	43	47	51	55	59	63
EPEQ	NLIN	-	36	40	44	48	52	56	60	64
S1	NMISC	-	41	46	51	56	61	66	71	76
S3	NMISC	-	43	48	53	58	63	68	73	78
SINT	NMISC	-	44	49	54	59	64	69	74	79
SEQV	NMISC	-	45	50	55	60	65	70	75	80
SBEND	NMISC	83	-	-	-	-	-	-	-	-
SSF	NMISC	84	-	-	-	-	-	-	-	-
FOUT	NMISC	-	96	-	93	-	94	-	95	-
FIN	NMISC	-	100	-	97	-	98	-	99	-
TOUT	LBFE	-	12	-	9	-	10	-	11	-
TIN	LBFE	-	16	-	13	-	14	-	15	-
MFORX	SMISC	7	-	-	-	-	-	-	-	-
MFORY	SMISC	8	-	-	-	-	-	-	-	-
MFORZ	SMISC	9	-	-	-	-	-	-	-	-
MMOMX	SMISC	10	-	-	-	-	-	-	-	-
MMOMY	SMISC	11	-	-	-	-	-	-	-	-
MMOMZ	SMISC	12	-	-	-	-	-	-	-	-
SDIR	SMISC	15	-	-	-	-	-	-	-	-
ST	SMISC	16	-	-	-	-	-	-	-	-

Table 4.20-3b PIPE20 Item and Sequence Numbers for the ETABLE and ESOL Commands

Name	Item	E
PINT	SMISC	17
PX	SMISC	18
PY	SMISC	19
PZ	SMISC	20
POUT	SMISC	21

4.20.3 Assumptions and Restrictions

4.20.4 Product Restrictions