EDEM API Contact Model | Not working correctly: Bonded-Particle Contact Model V3.5.0

Hi Bai,

I believe the model is setup correctly only the particle velocities are high (6 m/s) and the bond stiffness is also high (1e10 N/m3).

This typically means we need lower time-steps for the simulation to be stable, if you try closer to 1e-7 s for the time-step this should show more stable behaviour.

Regards

Stephen

Hi Bai,

I had a look at the case again and I notice there are two factories. 'New Factory 1' is a static factory creating the particles at t=0 s.

In the settings in bonded_particle_prefs.txt the bond formation time is set to 0 s so all particles created at t=0 s are bonded.

There is a second factory "new factory 2" which is inside the geometry section and this s a dynamic factory, so any particles created after t=0 s are not bonded, so give the impression of breaking although no bonds were ever created.

This is the difference between the in-built model which allows for bonds to be created at the same time as the particles are created, rather than at one specified point in time (0 s in this case).

In the code (gpu example) this is the point at which the bonds are formed. Its checking if the Contact property Bond Status is 0 at the specified time, and if so is creating the bond (increasing status from 0 to 1.

if (true == element2.isParticle())

    {

        //create bonds if:

        if (simulation.getCurrentSimulationTime() > m_requestedBondTime)

        {

            if (simulation.getCurrentSimulationTime() <= (m_requestedBondTime + simulation.getTimestep()))

            {

                if (m_BondStatus[0] == 0.0)

                {


                    //change bond status to set that it exists

                    m_BondStatusDelta[0] += 1.0;


                    //this is only recorded once, can later be used to check if bond is in compression or tension


                    customPropReal* m_BondRandDelta = contact.getCustomPropertyDelta(iBOND_RANDOM_COEF);


                     customPropReal random_number = (rand100(element1.getID(), element2.getID(), simulation.getCurrentSimulationTime()) - CUSTOM_REAL_CONST(50.0)) / CUSTOM_REAL_CONST(50.0); //number between -1 and 1


                    m_BondRandDelta[0] = random_number;


                   //tangentialPhysicalOverlap = real3();


                }

            }


        }

    }

If you want dynamic bonding you would have to change these conditions.

Regards

Stephen