A study of the dynamic mechanical behavior of elastomers under impact loading.

摘要

A study of the dynamic mechanical behavior of elastomeric materials under impact loading is presented. An unique experimental apparatus was designed and fabricated to measure the dynamic load-deflection behavior of elastomeric impact absorbers (bumpers), particularly of the type used in pneumatic fastening tools, and the apparatus was designed to duplicate actual service conditions in such a tool. The apparatus was used to measure the dynamic load-deflection behavior of thin cylindrical specimens having a thickness comparable to specimens tested using the classic Split Hopkinson Pressure Bar (SHPB), and a comparison between the two methods is given. Larger cylindrical specimens and an actual bumper design used in a small pneumatic fastening tool were also evaluated. The behavior of four typical elastomeric materials used in this application was examined and the forces, deflections and energy absorption characteristics of each are discussed. Data obtained using the SHPB were used to develop a dynamic material model for use in the ABAQUS/Explicit commercial finite element program to facilitate a study of the dynamic behavior elastomeric impact absorbers using finite element analysis. This material model was used to predict the dynamic load-deflection behavior of the cylindrical specimens and bumpers studied using the load-deflection apparatus, and a comparison with the experimental results was made to verify the computational results. The finite element analysis provided insight into the dynamic stress, strain and strain energy distributions resulting from impact, thus reducing the need to fabricate costly prototypes and perform extensive testing to characterize component behavior. The results of the work were also invaluable in the design of elastomeric impact absorbers, as they provided a means for eliminating much of the iterative redesign commonly used to develop elastomeric impact absorbers.