Dyna result doesn't match Test result

  • Thread starter lambertlai
  • Start date
  • Tags
    Match Test
In summary, the conversation is about the discrepancy between the results of a simple tensile test for steel MAT_024 in Dyna and the lab test results. The process involved collecting data and converting it to true stress and strain, using MAT_024 from Dyna, and extracting nodout and sec force. The results showed different maximum stress values for the same strain, leading to a question about the accuracy of the input and output graphs.
  • #1
lambertlai
3
0
I try many time to model a simple tensile test for steel MAT_024 but the graph doesn't match from Dyna result and Test result.
Process:
1. Collect data Tensile strain and stress convert to True stress and strain use formula True stress: eng. stress*(1+eng. strain). True strain= ln(1+eng. strain) and then the true strain convert to plastic strain = true strain - (true stress / Young modulus) and plot the graph
389954639.jpg


2. Use MAT_024 from dyna
389954647.jpg

389954647.jpg

3. Then I extract nodout and sec force.
389954850.jpg

LN1 is left node 1 (triangle on left)
RN1 is right node (triangle on right)

4. Eng stress= Force/Ao and eng. strain= delta Length / original length and plot the graph. (original area is 40, original length is 45mm)
389954524.jpg

389954523.jpg

389954525.jpg


Then the both result was different, why? What the misstake? Anyone can help me solve this problem?
 
Last edited:
Engineering news on Phys.org
  • #2
In the first figure, when you define the stress x plastic strain for the material, the maximum inputed value is around 0.5GPa for a strain of 0.3, but when you show the lab test stress x strain graph in the last figure, the maximum stress is around 0.37GPa for the same strain.
 
  • #3
The 1st figure is a plastic strain vs true stress as a input, is it right?
if true stress vs strain and lab test strain stress the max. stress is different right?
 

1. Why is there a discrepancy between the Dyna result and the Test result?

There are several factors that could contribute to the difference between the two results. It could be due to variations in experimental conditions, such as temperature or pH levels, or it could be a result of human error during the testing process.

2. How can we ensure that the Dyna result matches the Test result?

To ensure that the Dyna result matches the Test result, it is important to carefully control and standardize all experimental conditions and to carefully follow the testing protocol. It may also be helpful to repeat the experiment multiple times to confirm the accuracy of the results.

3. Is it possible that the Dyna result is more accurate than the Test result?

In some cases, the Dyna result may be more accurate due to its ability to provide real-time data and adjust for changing conditions. However, this is not always the case and it is important to carefully evaluate both results before drawing any conclusions.

4. Could there be a problem with the Dyna machine if the result doesn't match the Test result?

It is possible that there could be a problem with the Dyna machine, such as a malfunction or calibration issue, which could lead to a discrepancy between the two results. It may be necessary to troubleshoot the machine or have it serviced to ensure accuracy.

5. How can we use both the Dyna and Test results to gain a better understanding of our experiment?

By comparing and analyzing both the Dyna and Test results, scientists can gain a more comprehensive understanding of their experiment and potentially identify any sources of error or inconsistencies. Both results should be carefully considered and integrated into the overall conclusion of the experiment.

Similar threads

  • Materials and Chemical Engineering
Replies
1
Views
3K
Replies
5
Views
738
  • Mechanical Engineering
Replies
5
Views
861
  • Materials and Chemical Engineering
Replies
7
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
5
Views
14K
  • Engineering and Comp Sci Homework Help
Replies
2
Views
8K
  • Materials and Chemical Engineering
Replies
1
Views
4K
  • Engineering and Comp Sci Homework Help
Replies
2
Views
28K
  • Introductory Physics Homework Help
Replies
3
Views
2K
Back
Top