2.3.13 Variable thickness shells and membranes

Products: ABAQUS/Standard  ABAQUS/Explicit  

Problem description

For the general shell, membrane, and continuum shell elements the model consists of a tapered plate of length 100 and width 20, as shown in Figure 2.3.13–1. The plate is clamped at one end, and the thickness varies linearly across the plate from 3 at the clamped end to 1 at the free end. The model consists of 10 elements along the length and 2 across the width. For the model using continuum shell elements the thickness is defined by the nodal geometry.

For the axisymmetric elements the model consists of a tapered cylinder, with a radius of 1 × 106 and a length of 100, as shown in Figure 2.3.13–2. The cylinder is clamped at one end, and the thickness varies linearly along the length of the cylinder from 3 at the clamped end to 1 at the free end. The radius is chosen to be very large to ensure that the effects of circumferential stresses are negligible. The cylinder is meshed with 10 elements.

A linear elastic material with a Young's modulus of 10 × 109, a Poisson's ratio of 0, and a density of 8000 is used for all the tests. The thicker ends of the plate and cylinder are fully clamped. The shell elements are loaded with a bending moment of 3 per unit length at the thin end of the shell, and the membrane elements are loaded with an in-plane force of 50 per unit length at the thin end of the membrane.

Results and discussion

The ABAQUS/Standard results for shell and continuum shell elements are shown in Table 2.3.13–1. The ABAQUS/Explicit results for shell and continuum shell elements are shown in Table 2.3.13–2 and for membrane elements in Table 2.3.13–3. The differences in the ABAQUS/Explicit results are due to dynamic effects and mesh discretization. For the shell elements in ABAQUS/Explicit the results using a shell offset with a value of 0.5 are also shown in Table 2.3.13–2.

Input files

ABAQUS/Standard input files

varthick_std_s3r.inp

S3R element using *SHELL SECTION to define section properties.

varthick_std_s4r.inp

S4R element using *SHELL SECTION to define section properties.

varthick_std_s4r_edmom.inp

S4R element using *SHELL SECTION to define section properties. Bending moment applied with a distributed edge moment.

varthick_std_sc6r.inp

SC6R element using *SHELL SECTION to define section properties.

varthick_std_sc6r_sgs.inp

SC6R element using *SHELL GENERAL SECTION to define section properties.

varthick_std_sc8r.inp

SC8R element using *SHELL SECTION to define section properties.

varthick_std_sc8r_sgs.inp

SC8R element using *SHELL GENERAL SECTION to define section properties.

varthick_std_sc8r_eh.inp

SC8R element with enhanced hourglass control using *SHELL SECTION to define section properties.

varthick_std_sc8r_sgs_eh.inp

SC8R element with enhanced hourglass control using *SHELL GENERAL SECTION to define section properties.

ABAQUS/Explicit input files

varthick_s3r.inp

S3R element.

varthick_s3r_offset.inp

S3R element and a shell offset.

varthick_s4r.inp

S4R element.

varthick_s4r_offset.inp

S4R element and a shell offset.

varthick_sc6r.inp

SC6R element.

varthick_sc8r.inp

SC8R element.

varthick_sc6r_sgs.inp

SC6R element using *SHELL GENERAL SECTION to define section properties.

varthick_sc8r_sgs.inp

SC8R element using *SHELL GENERAL SECTION to define section properties.

varthick_sax1.inp

SAX1 element.

varthick_sax1_offset.inp

SAX1 element and a shell offset.

varthick_m3d3.inp

M3D3 element.

varthick_m3d4r.inp

M3D4R element.

varthick_m3d4r_hgc.inp

COMBINED hourglass option for membrane elements included for the sole purpose of testing the performance of the code.

varthick_m3d4r_hgv.inp

VISCOUS hourglass option for membrane elements included for the sole purpose of testing the performance of the code.

Tables

Table 2.3.13–1 ABAQUS/Standard shell bending results.

Element TypeTip Displacement ()Tip Rotation
EXACT2.00 × 10–68.00 × 10–8
S3R2.06 × 10–68.09 × 10–8
S4R2.02 × 10–67.91 × 10–8
SC6R1.93 × 10–6 
SC6R (sgs)1.93 × 10–6 
SC8R2.02 × 10–6 
SC8R (sgs)2.02 × 10–6 
SC8R*2.02 × 10–6 
SC8R* (sgs)2.02 × 10–6 
*ABAQUS/Standard results with enhanced hourglass control.

Table 2.3.13–2 ABAQUS/Explicit shell bending results.

Element TypeOffset ValueTip Displacement ()Tip Rotation
EXACT 2.00 × 10–68.00 × 10–8
SAX102.26 × 10–68.33 × 10–8
SAX10.52.23 × 10–68.26 × 10–8
S3R02.26 × 10–68.50 × 10–8
S3R0.52.23 × 10–68.38 × 10–8
S4R02.26 × 10–68.33 × 10–8
S4R0.52.24 × 10–68.23 × 10–8
SC6R 1.93 × 10–6 
SC8R 2.01 × 10–6 
SC6R (sgs)  1.93 × 10–6 
SC8R (sgs)  2.01 × 10–6 

Table 2.3.13–3 ABAQUS/Explicit membrane element results.

Element TypeTip Displacement ()
EXACT2.746 × 10–7
M3D32.751 × 10–7
M3D4R2.742 × 10–7


Figures

Figure 2.3.13–1 Tapered plate for general elements.

Figure 2.3.13–2 Tapered cylinder.