what type of ceramic B4C? Silicon Carbide?etc. ceramic thickness. size? what type of bullet - AP? HPR still pin? Also velocity.. is the projectile penetrating without shattering the ceramic?

all the above information is important in order to help you

My ceramic type is B4C,dimensions 120*120*3 mm^3.(thickness is 3mm).bullet is made up of steel.im using JC model for bullet and JH model for ceramic plate.bullet velocities are 200,400 and 700m/s.

For 200m/s I m getting error_negative volume in solid element

For 700 m/s ,bullet is crossing plate without any failure.

For 400m/s ,bullet is stopped completed by hitting plate(it is satisfactory result I guess)

the ceramic tile behavior is well known at those thicknesses. 700 m/s is a representative velocity - what is the backing? aramid or PE? Testing on clay? what are you trying to prove?

I am not following your " For 200m/s I m getting error_negative volume in solid element" statement - please elaborate.

Without knowing a lot of the details and on how are you conducting the test, specifics on the projectile, systems configuration....etc. it is hard to provide you with a more detailed answer.

David Cordova

sir there is no backing provided,i'm giving encastre boundary conditions on the side faces of the plate.

coming to the second statement,about error_,while i was applying 200m/s for bullet my simulation was not running and it terminated saying that "negavtive volume in solid elements"(basically it's an error that's why it terminated)

if possible i can give my .k file ,so that you can go through my inputs

200 m/s is a very low speed. More like a high velocity impact. no need ceramic for this. Thin ceramic has a different behavior than "thicker" ceramic. No backing for such a thin ceramic .....interesting.....just let me know what are you trying to prove or model

i have made three types of analysis with ranging from 200 to 700 m/s including 400 m/s.

but with 200 m/s it is terminated due to error.i would be delighted if you can give some hints to remove that error.

for the same material properties and condition at 400 m/s it is working well.

this is an example problem i will modify my geometry if it works well.but i was stuck with error_negative volume in solid elements.i have made some modification to erode the highly distorted element because of which i am getting negative volume.but the come of it is not practical one.(though error is eliminated)

Rokalla Dinesh Kumar Defining the right 'ELFORM' for the solid elements under *SECTION_SOLID helps in certain cases. Also the unit of defining the material parameters and the units the model is created matters.

Can you please tell me which element formation should be used in my case????

@pushya

I first suggest you to recheck with the units , if your material parameters are defined in SI units and the model is created in mm, it gives negative volume error, i suggest to recheck the model and Units and creating the model 0.12m x 0.12m x 0.003m plate and material parameters to be defined in SI. In case this doesnot work, Let me know which *MAT card are you using to define the ceramic plate?

Pushya Subramanyam

I rechecked my units and they were in SI units only.and I created the plate with same dimensions exactly(still problem exists).I'm using JH model for ceramic plate.and for bullet I'm using JC model.

Rokalla Dinesh Kumar From the picture it looks like the bullet is the one with negative volume error and since you haven't mentioned i am assuming Material card - JC model to be *MAT_120, for which parameter card 5 and 6 has parameters to define behaviour of material.(refer LS dyna Manual Vol II). Negative Volume occurs when material is either too soft or element volume is way too big. Give a try by defining the Load curve behaviour (may be LCDAM), making it more stiffer.

i am also assuming JH model to be *MAT_241, if you want the ceramic plate to break after impact, define FS=1 (Parameter card 3 ).(refer LS dyna Manual Vol II).

if you have already solved the problem let us know how you did it ?