Problem with spring and model

[Anonymous]

Hello, I am a member of the HORUS UPV estructures team. Our team has been trying to analyze the front landing gear of the drone we are building and we have faced several issues trying to characterize the spring. The error might be in the geometry itself but we cant identify it. If anyone could help, it would be highly appreciated. 

[Anonymous]

Hello, I am a member of the HORUS UPV estructures team. Our team has been trying to analyze the front landing gear of the drone we are building and we have faced several issues trying to characterize the spring. The error might be in the geometry itself but we cant identify it. If anyone could help, it would be highly appreciated. 

[John_Holtz]

Hi @Anonymous 

We need more information:

1. What version of Inventor Nastran are you using?
2. What issues or errors are you encountering?
3. The assembly file by itself is not useful. We need all of the part files, too. Please compress the assembly files (.iam) and part files (.ipt), and attach the .zip/.rar file to the forum post.

[John_Holtz]

Hi @Anonymous 

We need more information:

1. What version of Inventor Nastran are you using?
2. What issues or errors are you encountering?
3. The assembly file by itself is not useful. We need all of the part files, too. Please compress the assembly files (.iam) and part files (.ipt), and attach the .zip/.rar file to the forum post.

[Anonymous]

The version of Nastran InCad and Inventor we are using is 2020. The main problem we are facing is that the spring that is located between the two cylinders is not working as it should according to the spring constant and the load applied. Thank you for your help.

[Anonymous]

The version of Nastran InCad and Inventor we are using is 2020. The main problem we are facing is that the spring that is located between the two cylinders is not working as it should according to the spring constant and the load applied. Thank you for your help.

[John_Holtz · Accepted solution]

Hi @Anonymous 

There is something wrong with the contact between the outside of the piston and the inside of the cylinder. The contact force in the Z direction should be 0, but there is a relatively large Z contact force.

 N NI think this is not the issue, but I see that "Continuous Meshing" is checked. You do not want to use continuous meshing in this model. You want the piston free to slide inside the cylinder.

My suggestion is to run the analysis using Nonlinear Static Stress and set the following:

• Set "Analysis > Edit > Options > Large Displacements " to OFF.
• Set "Nonlinear Setup > Number of Increments" to 1.

This gives the expected displacement of 20 N/(9067 N/m) = 0.0022 m.

[John_Holtz · Accepted solution]

Hi @Anonymous 

There is something wrong with the contact between the outside of the piston and the inside of the cylinder. The contact force in the Z direction should be 0, but there is a relatively large Z contact force.

 N NI think this is not the issue, but I see that "Continuous Meshing" is checked. You do not want to use continuous meshing in this model. You want the piston free to slide inside the cylinder.

My suggestion is to run the analysis using Nonlinear Static Stress and set the following:

• Set "Analysis > Edit > Options > Large Displacements " to OFF.
• Set "Nonlinear Setup > Number of Increments" to 1.

This gives the expected displacement of 20 N/(9067 N/m) = 0.0022 m.