Periodic displacement loads decompose with 4 load steps in Abaqus

 I want to simulate a dynamic motion of a pipe under periodic displacement loads.

The whole periodic displacement loads was decomposed into 2 halves. The first half was from 0 at initial configuration to a middle configuration to final configuration, then the second half goes back from final configuration to middle configuration, to initial configuration (Fig.1). The displacement loads of these 4 configurations was given. Using Abaqus Explicit, the whole dynamic motion was simulated.

But, I find a problem as follow.

1.     The Kinetic energy was discontinuity at the middle configuration. In other words, the Kinetic energy at the middle configuration shouldn’t be 0 (Fig.2).

The attachment is the .inp file for solve, just only running “T4Solve3_CompPrd-ok.inp” file under the Abaqus work directory.

(The inp file can't upload the web. ) 

Can anyone suggest a reason as to why this would happen?

Thanks in advance for any advice.