Understanding ABAQUS Energy results 2

[Ander Azpi]

Hello everyone!

I have lauched an impact simulation, in which a car impacts a wall. The car has a predefined velocity and all materials have plastic definitions. The wall is rigid. The energy results are shown in the image I attach.

Is this correct?? Is it okay that the kinetic energy decreses??

Thanks in advance

 

[FEA way]

Check the energy balance equation in the documentation and take a look at how individual components are related to each other. It may help to plot them separately and in pairs. You should do the standard checks first (for example, ALLAE vs ALLIE to verify if hourglassing is present in the model). Notice that plastic dissipation is high in this case (a lot of energy goes into plastic deformation) which is normal in such analysis.

 

[NRP99]

Let us consider that the mass of car is 'M' and car travelling with velocity 'v', impacts the rigid wall. The kinetic energy of car = (1/2)*M*v^2. As per law of conservation of energy-Energy shall be never created nor destroyed. So whatever kinetic energy gained by the car (of course by converting the fuel latent heat energy)is then transferred to rigid wall. But rigid wall can't absorb the energy since its "rigid". So where the energy goes then.

Energy balance equation -Energy In-Energy Out=Total energy stored in the system. Assuming car as the system (In thermodynamic sense), and putting the energy balance-

Energy in (ALLKE or ALLIE)-Energy absorbed by rigid wall(0, since rigid wall doesn't move and doesn't absorb any energy since its rigid)=Amount of energy absorbed by car in plastically deforming the body parts(ALLPD) + Amount of energy released for dissipating the frictional energy between parts (ALLFD)+ Amount of energy released for dissipating the heat energy between parts (ALLJD)+ Strain energy stored by car (ALLSE)+ so on...

You can check the Total energy of model against its conversion to other energies using energy balance equation using this link. So now kinetic energy is converted to other energies after impact, is it going to remain constant or decrease?