impact contact force

[loyal979]

Hi All,

I am working on an impact simulation using ABAQUS/Explicit. I'm having trouble with estimating the contact force of the two objects. The impactor is 3D discrete rigid body, I defined the total mass to it and its initial velocity using the predefined field in the load section. I have used general contact algorithm and surface to surface contact for the interaction definition. Also, I requested the contact force from the history field output using the CFN output option. The estimated contact force I get always over estimated when I compare it to the experimental result. I know that the two major factor that affect the contact force is the mass and the drop height (which is being taking care of by defining the velocity).

I am just wondering if there are other factors causing this issue?

Please share with me your feedback. Thank you in advanced.

 

[FEA way]

In general this may be caused by some assumptions/simplifications in the analysis as compared to the experiment. The largest simplification here is that you use rigid impactor. Material data may play some role too.

 

[loyal979]

Thank you for your reply.
Do you think using Cohesive element type for the plate would improve the results?

 

[FEA way]

You could use cohesive elements if there was an adhesive connection between parts of the model. But if it's a simple plate then this is not a good idea.

Can you show a picture of your model with mesh ? I will try to suggest the best approximation for this case.

 

[Dave442]

be careful using CFN history output. If I remember it correctly:

CFN1, CFN2 and CFN3 are the scalar sum of contact force components in the three global directions.

For certain geometries (e.g. cylindrical) equal and opposite forces will cancel each other.

 

[loyal979]

FEA way: I dont have a picture of the model with mesh at this moment. but the model is composite laminate modeled with 3D solid elements and consists of 12 layers.

Dave442: Yes, you are correct. I should be more clear with this but I am outputting only CFN3 since my impact load in z direction.

Thanks both.

I guess the only thing that I could think of right now is as FEA way said the material data and maybe the element type probably.

 

[loyal979]

I am just curious to know how the mesh and the assigned material of the plate influence the impact force of the impactor. please share your valuable feedback with me. Thanks!

 

[FEA way]

Both assumption that impactor is rigid and use of specific material data may influence impact force results since the deformation is different. Flexible impactor deforms during the impact and thus contact area changes as well as impact duration. Similar effect may be observed when we change stiffness of the target.

 

[loyal979]

Thank you FEA way for your feedback.