SS-V: 5030 Reactions at the Ends of Axially Loaded Plastic Bar

Test No. VNL04 Find reactions at the fixed ends and maximum displacement of a bar axially loaded beyond plasticity.

Definition



Figure 1.

Bar dimensions are 10 x 10 x 200 mm. Distance between loaded point and left end A=50 mm. Strain-stress curve of the bar material is defined by the power law:

σ=Kεn

Where,
K
Strength coefficient
n
Must be in the range [0,1]
n =0
Material is perfectly plastic.
n =1
Material is elastic.
The material properties are:
Properties
Value
K
530 MPa
n
0.26
Poisson's Ratio
0


Figure 2. Corresponded strain-stress curve

The study was performed for the following load F values: 30000 N, 47000 N, 55000 N, and 60000 N. These loads cover the full range of elastic-plastic response of the bar.

Reference Solution

One-dimensional analytical reference solution is described here.

The length of the bar does not change under the load.

A0ε1dx  LA0ε2dx = 0

or,

A0nN/(K*A)dx  LA0n(FN)/(K*A)dx = 0

Where,
ε1
Tensile strain at the left span of the bar.
ε2
Compressive strain at the right span of the bar,
N
Reaction force at left end of the bar.
R=FN
Reaction force at the right end of the bar.
A
Bar cross-section area

From this equation you can find the reaction at the left end of the bar.

N = F/(1+(a/b)n)

and R = FN at the right end.

Results

Bar was modeled as a 3D solid with immovable ends. Axial force F could not be applied precisely at the solid bar axis, so four line spots were created at the bar sides and total load F was uniformly distributed over the spots (Figure 3).
Figure 3.

The following table summarizes the reaction force results.
Force F [N] SOL Reference, Reaction [N] SimSolid, Reaction [N] % Difference
30000 17128 17522 2.3%
47000 26834 26987 0.5%
55000 31401 31660 0.8%
60000 34256 34490 0.6%