  Lattice structures and thin-walled tubes are two types of energy-absorbers
widely studied and applied in engineering practice. In this study, a new type
of lattice-structure filled thin-walled tube (LFT) was proposed. In this new
type of LFT, a BCC-Z lattice structure was filled into a square thin-walled
tube. Then using data mining, a 3-D geometric design with five design variables
was conducted on this new LFT. Using Latin Hypercubic sampling algorithm, 150
design cases were generated. Numerical models were then developed to simulate
their crush behavior, and the simulation dataset was used for data mining. The
results showed that (1) Filling the BBC-Z lattice structure into a thin-walled
tube can significantly improve the energy absorption (EA) capacity of the
structure. (2) The decision trees generated in the data mining process
indicated that the rod diameter d of lattice structure is the key design
variable that has most significant impact on EA, followed by m and n. (3) The
design rules to build LFTs with high EA efficiency (SEA>=16 kJ/kg and
CFE>=45%), high total EA (SEA>=16 kJ/kg and EA>=6 kJ), and lightweight (SEA>=16
kJ/kg and Mass<=0.45 kg) were obtained from decision trees. The ideal
configurations of LFT corresponding to these three objectives are: d>2 mm, n>2
and m>3 for high EA efficiency; d>2 mm, n>2 and m>3 for high total EA; and d>2
mm, n>2, m<=4 and t<=1.7 mm for lightweight.
