Kinematic Hardening Parameters Identification with Finite Element Simulation of Low Cycle Fatigue using Genetic Algorithm Approach

This paper deals with finite element (FE) simulation to characterize the low cycle fatigue (LCF) behavior using genetic algorithm (GA) approach. Non linear version of Chaboche’s kinematic hardening material model is used to address the stable hysteresis cycles of the material. Cyclic hardening phenomenon is addressed by introducing exponential isotropic hardening rule in the material model. The elastic plastic FE code ABAQUS is used for finite element simulation of LCF behavior. The plastic modulus formulation is coupled with the isotropic/kinematic hardening rule together with the yield surface consistency condition Incremental plasticity theories is used to study the cyclic plastic stress-strain responses. The GA approach is used to optimize the isotropic/ kinematic hardening parameters of SS 316 steel. The validity of GA method is verified by comparing its simulation results with those of manual parameter determination approach available in the literature. The simulation results confirm the potentiality and efficacy of the Genetic algorithm

Mechanism of Gully-Head Retreat - A Study at Ganganir Danga, Paschim Medinipur, West Bengal

Twenty three gully heads were randomly selected from a representative gully basin at Ganganir Danga, Paschim Medinipore West Bengal for understanding mechanism of gully head retreat. The study was made during June to September, 2011. Height and slope of gully heads, width at top and base of the gully head were monitored. Geotechnical properties of soil like cohesion and angle of internal frication, bulk density were measured to estimate shear stress and shear strength at gully head. Linear retreat of the gully heads was monitored by pegging technique. Depths of tension cracks were measured at regular interval. The study shows that, gully heads retreated at different rates ranging from 13 cm to 121 cm depending on instability factors. Gully heads are few times steeper than angle of internal friction that introduces instability. Alcove structure and plunge pools, developed at the bottom of gully heads, lead to formation of overhanging slope. Near vertical and overhanging slope of considerable height develop tension cracks leading to mass failure and gully head retreat. Number of instability factors is operating at the gully heads and no linear relation can be established between these factors and gully erosion.Key words: Tension crack, Mass failure, Gully head retreat, Geotechnical properties