Design optimization of tank track pad meta-material using the Unit Cell Synthesis Method

The elastomeric backer pad on the M1 Abrams tank track experiences highly cyclic and dynamic loads during normal operating conditions. As a result, extensive heat is generated within the pad due to its viscoelastic hysteretic nature which leads to its early failure. Research has been carried out in the past at Clemson University to design a meta-material that will mimic the deformation behavior of the elastomeric backer pad but will be made out of a linearly elastic constitutive material to eliminate hysteresis. A meta-material in this context is an artificial material in the form of a periodic structure that exhibits effective properties that differ from its constitutive material. Previous attempts to design a feasible meta-material as an effective replacement to the existing elastomeric backer pad have been unsuccessful. The work carried out in this research therefore, is focused on developing a meta-material that satisfies all the application specific requirements. The meta-material is designed based on the steps prescribed by the Unit Cell Synthesis Method which was developed in previous research. Using this method, a unit cell based periodic meta-material can be designed that exhibits nonlinear deformation behavior by implementing various combinations of different elemental geometries that show geometric nonlinearity under deformation. The idea is to attain a targeted nonlinear deformation response of the meta-material structure by tuning the geometric nonlinearities of one or multiple entities in order to replace the material nonlinearity of the target material. A modification is proposed to the original method to make it more efficient by introducing a multi-objective optimization step that considers all the relevant feasibility criteria concerning the meta-material design. Two unit cell based meta-material concepts are evaluated and a best meta-material design is chosen based on the results obtained from the multi-objective optimization problem. The optimized meta-material is then subjected to dynamic tank wheel roll-over conditions to compare its deformation response with that of the original pad. Finally, conclusions are drawn and scope for future work is discussed.