A mechanical model for the elastic–plastic behavior of metallic bars

A simple mechanical model, which consists of a particular assemblage of elementary units composed of elastic springs and frictional sliding blocks, appears suitable for describing the various aspects of the elastic±plastic behavior of steel bars in standard tensile tests: oscillations in the average stress±strain curve, the distinction between local and global responses, instability due to the transition from an upper to a lower yield point, the spread of plastic deformation, strain-hardening behavior, elastic unloading and the in¯uence of loading-device sti€nes