I am trying to model low velocity impact of composite materials with abaqus explicit. the model consists of an 8 layered composite plate that is impacted by a rigid projectile. The model works correctly and I am able to demonstrate the delaminations that occurs. However, when the history output for the internal energy is studied it begins at 0 and then raises to above the intially supplied kinetic energy for the system. If the impactor had an inital energy of 15 j, the internal energy of the ssytem may raise to above 30. I have supplied the two history outputs that this occurs in. Does anyone know why this is occuring?
Internal energy can results from static forces or quasi-static forces and kinetic energy does not have to be the only source of internal energy, so even if the loading is static, it yields internal energy.
Dear Bentley,
Check total energy, ETOTAL, history output. It should be constant, or maybe with little changes during the impact process. If it increases considerably, numerical results are not correct. Also, check artificial strain energy history output. It should be near to zero relative to total energy value (does not increase more than 5% of ETOTAL). Again, if it increases considerably, unrealistic strains resulted from hourglass control, affected the results.
Regards,
M. Khodaei
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