A criterion to set workability limits for internal ductile fracture (voids and cracks) in the cold heading of dual phase steel is presented. This criterion is based on the damage estimated by the history of the equivalent plastic strain and stress triaxiality as a weighting function. Stress triaxiality is defined by the dimensionless parameter (σ m /σ ) where σ m is the mean stress or the hydrostatic stress and σ is the equivalent stress. The basic mathematical expression for the ductile fracture criterion by voids and cracks is the criterion proposed by Oyane 1). The methodology to determine the parameters in the workability criterion is explained in this work. This methodology employs the drop weight compression test to simulate the cold heading process in conjunction with finite element analysis (implemented within ABAQUS/Explicit). Metallographic inspection of the deformed specimens was performed to locate the failed zones inside the adiabatic shear band. The failure measure in this work is taken to be the appearance of microscopic voids and cracks along the localized adiabatic shear band that exceed 10 μm in length. The presence of these internal defects can result in eventual splitting of the fastener's heads.
|Original language||English (US)|
|Number of pages||8|
|State||Published - May 1 2005|
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering