abaqus分析热轧椭圆空心型钢的抗压强度（二）

EHS.cae

Pick the centre point or enter X and Y coordinates as 0,0

Pick a major axis of ellipse or enter X and Y coordinates as 75, 0.

Pick a minor axis of ellipse or enter X and Y coordinates as 0,37.5.

Click on Done

Enter base extrusion depth as 300.

The finished part will be an elliptical hollow section with the major axis diameter of 150 mm and the minor axis diameter of 75 mm. The depth of this stub column is 300mm.

2. Material and section properties

Define steel as elastic-plastic material.

Click on edit name, enter name as Steel.

Mechanical → Elasticity → Elastic

Enter Young’s modulus as 217,700 N/mm2 and Poisson’s ratio as 0.3.

Mechanical → Pasticity → Plastic

Enter plastic properties as:

Yield stress	Plastic strain
373	0
514	0.18 (assume)

Define elliptical tube section.

Name the section as EHS section

Category: Shell

Type: Homogenous

Enter shell thickness as 4.22 mm and keep all other default options.

Click on Part → EHS → Section Assignment

Select the entire section.

Assign EHS Section to the selected elliptical hollow tube.

Shell Offset Definition: Bottom. This will ensure that the entire shell thickness is extruded inside the outer tube diameter.

3. Assembly

Assemble the parts by clicking on Assembly → instances → parts → EHS. Keep all other values as default.

Define rigid reference points at top and bottom of the tube.

Assembly → features

Tools Tab → Reference point

Select point to act as a reference point or enter X, Y and Z coordinates: 0,0,0 to enter Top reference point.

Assembly → features → RP-1 and right click to rename the refence point as Tref.

Repeat the procedure to define the bottom reference point.

Select point to act as a reference point or enter X, Y and Z coordinates: 0,0,300 to enter Bottom reference point.

Rename RP-2 as BRef

4. Constraints

• Tie top and bottom edge with rigid reference points

First define sets for reference points and tube edges.

Define sets for top and bottom reference points as well.

Tie top reference point with top edge of the elliptical tube.

Create Constraints → Name it as TieTop.

Type: Rigid body

This will tie up all the elliptical tube’s top edge with the rigid reference point.

Click on Tie (nodes)

Select top edge of the tube.

Click on Reference point to choose the top reference point Tref

When constraints are applied to the tube edges and reference points, it looks like as follows:

5. Defining steps and output requests

Create a single static, Riks step after the initial step. Accept the default output request.

Include the effects of geometric nonlinearity and set the following stopping criteria: Maximum displacement: 10 mm

Degree of freedom (DOF): 3 (which is z direction)

Node Region: TopRef (Top reference point set)

Set incrementation type to automatic

Maximum number of increments to 1000

Arc length increment to 0.01

6. Boundary condition and loading

Click on Steps → initial → BCs to define FixBot boundary condition.

The bottom reference point is fixed in all directions with encastre boundary condition.

The bottom reference point is fixed in all directions with encastre boundary condition.

This time, define Displacement rotation boundary condition at the top reference point.

The Top reference point is fixed in all direction except z direction where is the displacement is to be applied in the static Riks step.

Load top reference point:

Steps – ApplyDisp and loadTop BC

Apply 10 mm displacement to top reference point.

7. Mesh creation and job definition

Go to part and mesh

Go to seed part and define approximate global size of 10

Go to mesh control and accept all defaults

Click on element type and use S4R shell element

Mesh – part

Save file as EHS

Make sure to set working directory to save all files in a single folder.

Define job now and accept all defaults

Jobs – EHS_FE and data check

Data check completed with no errors.

Jobs – EHS_FE - Submit

Then monitor the job

Job is completed without errors.

8. Post-processing

• Load deflection curve

Right click and Results

Click on XYdata and ODB field output

Click on position: Unique Nodal

Click on displacement U3

Click on Elements Nodesets and TopRef

Plot and save

But this will give displacement versus arc length, we need load versus displacement curves.

Click on XYdata, ODB field output, reaction force and RF3, TopRef, plot and save

XYData – Operate on Data

Click on combine

Double u3

Double click on RF3

Divide RF3 by 1000 to convert it into kN

Plot and save as Load-Defl

	Ultimate load, Fu (kN)	End shortening at Fu (mm)
Test	554
FE

• Deflected shape