1.3.11 Initial curvature of beams and shells

Product: ABAQUS/Standard  

Elements tested

B21    B21H    B22    B22H    B23    B23H    B31    B31H    B31OS    B31OSH    B32    B32H    B32OS    B32OSH    B33    B33H   

PIPE21    PIPE21H    PIPE22    PIPE22H    PIPE31    PIPE31H    PIPE32    PIPE32H   

S4    S4R    S4R5    S8R    S8R5    S9R5    STRI3    STRI65    SC6R    SC8R   

Problem description

Material:

Linear elastic, Young's modulus = 30 × 106, Poisson's ratio = 0.3.

Boundary conditions:

End A is clamped.

Loading:

25.0 at end B.

Initial curvature is defined by specifying the direction cosines of the normals at the two ends.

Gauss integration is used for the shell cross-section for the S4R elements.

Reference solution

Reference results are generated from models consisting of 20 B33 cubic beam elements. (Since only one element is used for modeling, if the direction cosines of the normals are not used, the solution will correspond to straight beam theory.) The reference tests use SECTION=RECT, SECTION=I, or SECTION=PIPE. These sections correspond to regular beams and shells, open section beams, and pipes, respectively.

Regular beams and shells (see erefrrs7.inp):

Displacements, curved beam solution

2.1735 × 10–5, 1.4570 × 10–4.

Displacements, straight beam solution

1.6667 × 10–5, 0.0.

Open section beam elements (see erefois7.inp):

Displacements, curved beam solution

3.1946 × 10–4, 1.0962 × 10–3.

Displacements, straight beam solution

2.8153 × 10–4, 0.0.

Pipe elements (see erefpps7.inp):

Displacements, curved beam solution

2.9461 × 10–5, 4.5078 × 10–5.

Displacements, straight beam solution

2.7922 × 10–5, 0.0.

Results and discussion

Table 1.3.11–1 Regular beams and shells.

Element TypeRemarks
B21 (1-element mesh)1.6667 × 10–50.0Straight*
B21 (Refined mesh)2.1715 × 10–51.4343 × 10–4Curved
B21H (1-element mesh)1.6667 × 10–50.0Straight*
B21H (Refined mesh)2.1665 × 10–51.4343 × 10–4Curved
B222.1085 × 10–51.4686 × 10–4Curved
B22H2.1085 × 10–51.4686 × 10–4Curved
B232.0873 × 10–51.4549 × 10–4Curved
B23H2.0873 × 10–51.4549 × 10–4Curved
B31 (1-element mesh)1.6667 × 10–50.0Straight*
B31 (Refined mesh)2.1715 × 10–51.4343 × 10–4Curved
B31H (1-element mesh)1.6667 × 10–50.0Straight
B31H (Refined mesh)2.1715 × 10–51.4343 × 10–4Curved
B322.1084 × 10–51.4686 × 10–4Curved
B32H2.1084 × 10–51.4686 × 10–4Curved
B332.0873 × 10–51.4548 × 10–4Curved
B33H2.0873 × 10–51.4548 × 10–4 Curved
S4 (1-element mesh)1.6292 × 10–50.0Straight*
S4 (Refined mesh)2.1607 × 10–51.4314 × 10–4Curved
S4R (1-element mesh)1.6666 × 10–50.0Straight*
S4R (Refined mesh)2.1661 × 10–51.4340 × 10–4Curved
S4R5 (1-element mesh)1.6666 × 10–50.0Straight*
S4R5 (Refined mesh)2.1667 × 10–51.4344 × 10–4Curved
S8R2.1036 × 10–51.4508 × 10–4Curved
S8R52.1001 × 10–51.4638 × 10–4Curved
S9R52.1001 × 10–51.4638 × 10–4Curved
STRI31.6667 × 10–50.0Straight
STRI65 2.0750 × 10–51.4331 × 10–4Curved
SC6R2.1673 × 10–51.425 × 10–4Curved
SC8R2.156 × 10–51.2402 × 10–4Curved
SC8R1.6608 × 10–52.5028 × 10–4Straight
SC8R**2.1491 × 10–51.4175 × 10–4Curved
SC8R**1.6276 × 10–52.4271 × 10–4Straight

Table 1.3.11–2 Open section beam elements.

Element TypeRemarks
B31OS (1-element mesh)2.8153 × 10–40.0Straight*
B31OS (Refined mesh)3.2287 × 10–41.0790 × 10–3Curved
B31OSH (1-element mesh)2.8153 × 10–40.0Straight*
B31OSH (Refined mesh)3.2287 × 10–41.0790 × 10–3Curved
B32OS (1-element mesh)3.1787 × 10–41.1048 × 10–3Curved
B32OSH (Refined mesh)3.1787 × 10–41.1048 × 10–3Curved

Table 1.3.11–3 Pipe elements.

Element TypeRemarks
PIPE21 (1-element mesh)2.7922 × 10–50.0Straight*
PIPE21 (Refined mesh)2.9768 × 10–54.4373 × 10–5Curved
PIPE21H (1-element mesh)2.7922 × 10–50.0Straight*
PIPE21H (Refined mesh)2.9768 × 10–54.4373 × 10–5Curved
PIPE22 (1-element mesh)2.9572 × 10–54.5435 × 10–5Curved
PIPE22H (1-element mesh)2.9572 × 10–54.5435 × 10–5Curved
PIPE31 (1-element mesh)2.7922 × 10–50.0Straight*
PIPE31 (Refined mesh)2.9768 × 10–54.4373 × 10–5Curved
PIPE31H (1-element mesh)2.7922 × 10–50.0Straight*
PIPE31H (Refined mesh)2.9768 × 10–54.4373 × 10–5Curved
PIPE32 (1-element mesh)2.9572 × 10–54.5435 × 10–5Curved
PIPE32H (1-element mesh)2.9572 × 10–54.5435 × 10–5Curved

* These are first-order elements and are unable to capture initial curvature with a one-element mesh. However, a refined mesh for these elements yields very good results. Due to the lack of symmetry for triangular meshes, the displacements at the nodes that are at point B may differ slightly. The maximum values are documented here.** These results are obtained using enhanced hourglass control.

Input files

Coarse mesh tests:


eb22rms7.inp

B21 elements.

eb2hrms7.inp

B21H elements.

eb23rms7.inp

B22 elements.

eb2irms7.inp

B22H elements.

eb2arms7.inp

B23 elements.

eb2jrms7.inp

B23H elements.

eb32rms7.inp

B31 elements.

eb3hrms7.inp

B31H elements.

ebo2ims7.inp

B31OS elements.

ebohims7.inp

B31OSH elements.

eb33rms7.inp

B32 elements.

eb3irms7.inp

B32H elements.

ebo3ims7.inp

B32OS elements.

eboiims7.inp

B32OSH elements.

eb3arms7.inp

B33 elements.

eb3jrms7.inp

B33H elements.

ep22pms7.inp

PIPE21 elements.

ep2hpms7.inp

PIPE21H elements.

ep23pms7.inp

PIPE22 elements.

ep2ipms7.inp

PIPE22H elements.

ep32pms7.inp

PIPE31 elements.

ep3hpms7.inp

PIPE31H elements.

ep33pms7.inp

PIPE32 elements.

ep3ipms7.inp

PIPE32H elements.

ese4sms7.inp

S4 elements.

esf4sms7.inp

S4R elements.

es54sms7.inp

S4R5 elements.

es68sms7.inp

S8R elements.

es58sms7.inp

S8R5 elements.

es59sms7.inp

S9R5 elements.

es63sms7.inp

STRI3 elements.

es56sms7.inp

STRI65 elements.

esc8sms7.inp

SC8R elements.

esc8sms7_eh.inp

SC8R elements with enhanced hourglass control.

Fine mesh tests:


eb22rfs7.inp

B21 elements.

eb2hrfs7.inp

B21H elements.

eb32rfs7.inp

B31 elements.

eb3hrfs7.inp

B31H elements.

ebo2ifs7.inp

B31OS elements.

ebohifs7.inp

B31OSH elements.

ep22pfs7.inp

PIPE21 elements.

ep2hpfs7.inp

PIPE21H elements.

ep32pfs7.inp

PIPE31 elements.

ep3hpfs7.inp

PIPE31H elements.

ese4sfs7.inp

S4 elements.

esf4sfs7.inp

S4R elements.

es54sfs7.inp

S4R5 elements.

esc6sfs7.inp

SC6R elements.

esc8sfs7.inp

SC8R elements.

esc8sfs7_eh.inp

SC8R elements with enhanced hourglass control.