Material density is irrelevant.

Resolve the vertical & horizontal components at the point of impact along the discharge curve according to the information on Lyle's link.

If material doesn't bounce back what's the point of the plate? ■

Hi all,

Here the dificulty is to estimate the real contact time in wich the variation of the quantity of movement occurs.

Nothing better than to do some experiments.

Have someone of you already done it?

Regards

Alexandre Calijorne ■

Density is very important.

Particles have various arresting velocities, vectors, and inertias according to their: mass flow characteristics, contact angles, particle shapes, in-situ density of the individual particles, general particle asperity, quasi-surface friction, particle rheology (elasticity, plasticity, viscoelastic damping properties that may by strain-rate dependent), particle size distribution and initial particle velocity vectors, and dynamics of particle bed being impacted to name a few.

The above complexity is complicated for a hand calculation method, but easy for a well developed Discrete Element Model (DEM).

Engineers used to apply water pressure formulae, such as water flow stream on a plate. This is a crude way to define the science, but with fine, dry particles that do not aerate, it can give acceptable results.

Rocket science anyone? ■

Originally Posted by nordell

........

Particles have various arresting velocities, vectors, and inertias according to their: mass flow characteristics, contact angles, particle shapes, in-situ density of the individual particles, general particle asperity, quasi-surface friction, particle rheology (elasticity, plasticity, viscoelastic damping properties that may by strain-rate dependent), particle size distribution and initial particle velocity vectors, and dynamics of particle bed being impacted to name a few.

.......

Engineers used to apply water pressure formulae, such as water flow stream on a plate. This is a crude way to define the science, but with fine, dry particles that do not aerate, it can give acceptable results.

Rocket science anyone?

So what density should this punter be using?■

His 1.77 t/cm would be a good start. ■

If you estimate the co-efficient of restitution (Cr) (generally this will be quite low because the material will flow off the impact plate, not bounce straight back). The real impact time does then not need to be known.

You can resolve the velocity into velctors and analyse the forces in both directions.

Using the bernouli eqn for water streams, the equation simplifies down to

F = 0.5 x Area of impact x density x velocity prior to impact^2 x [1-Cr]

As Nordell said, this is based upon the water stream from a plate but can be used to give an indication of the force on the impact plate.

Hope this helps

Cheers,

Kristan ■

Originally Posted by kristan duthie

....

F = 0.5 x Area of impact x density x velocity prior to impact^2 x [1-Cr]

As Nordell said, this is based upon the water stream from a plate but can be used to give an indication of the force on the impact plate.

Hope this helps

Cheers,

Kristan

As louis panjang said density is irrelevant since area of impact x density x velocity are dependent on the mass flow.■

Hi everyone,

Does it make sense...to put springs under the impact plates to improves its life?

The resultant forces should results lower because the interaction time between plate and material piece will increase.

Has someone already tried this?

Regards ■