Dynamic Behavior of 3D Biaxial Spacer Weft-Knitted Composite T-Beam Under Transverse Impact

Abstract

The dynamic responses of T-beam structures made of 3D biaxial weft-knitted composite were tested under different impact velocities to characterize strength and energy absorptions of the T-beam with different rib heights. The transverse impact tests were carried out at a modified split Hopkinson pressure bar (SHPB) apparatus and also compared with the quasi-static test results. A user defined material subroutine named MAT/UMAT, which was based on a unit-cell model of the 3D knitted composite was developed to calculate the impact responses with a commercial FEM code ABAQUS. The load-displacement curves of the composite T-beam with different rib height under impact were calculated and compared with those from experiment. Mechanisms of the load-displacement curve fluctuations obtained from experiments are also discussed. The effect of the rib height on the load-displacement cures and energy absorptions have also been analyzed. Such an approach could also be extended to the design of other 3D knitted composite structures with different shapes under impulsive loading.

Keywords:

• impact responses
• 3D biaxial spacer weft-knitted composite T-beam
• rib height
• modified split Hopkinson pressure bar (SHPB)
• user defined material subroutine
• FEM

ACKNOWLEDGEMENTS

The authors gratefully acknowledge financial support from the National Science Foundation of China (50675032, 10802022, and 10872049) and the Key-grant Project of Chinese Ministry of Education (No. 309014). The Star Program (08QA14008) are also gratefully acknowledged.

We also thank the two anonymous referees for useful and constructive suggestions which have resulted in significant improvement of the manuscript.