The Proceedings of The Computational Mechanics Conference

The kinetics of a solid-liquid interface of iron with a triple point is investigated by performing a large-scale molecular dynamics simulation on a graphics processing unit(GPU). A grain boundary groove evolves at the triple point of a solid-liquid interface with a bccS3(111) tilt grain boundary during solidification, whereas a solid-liquid interface with a twin boundary of small grain boundary energy is almost planar except in the vicinity of the triple point. This agrees with the experimental observation and its conventional interpretation. Moreover, it is found that the equilibrium temperature at which the solid-liquid interface does not move is in close agreement with to the curvature undercooling estimated by the Gibbs-Thomson effect.

View full abstract

The whole process of a prismatic dislocation loop (PDL) formation around a misfitting spherical inclusion embedded in a homogeneous isotropic matrix is studied using level set dislocation dynamics. Two small half loops are first punched out around a spherical particle on a specific cylindrical surface along which the magnitude of the misfit shear stress reaches the maximum among all the homocentric cylinder surfaces. The edge dislocation segments glide away from the inclusion-matrix interface under the influence of the shear stress, while the screw components cross slip around the cylindrical surface. When two ends with opposite orientations of the top and bottom half dislocation loops intersect, the screw segments annihilate and a PDL is finally produced.

View full abstract

Post-impact pedestrian kinematics is complex and depends on various factors such as impact speed, height of the pedestrian, front-end profile of the striking vehicle and pedestrian posture, among others. A detailed study of NASS-PCDS (National Automotive Sampling System - Pedestrian Crash Data Study) showed that the vehicle-pedestrian interaction in frontal crashes could be categorized into four types. Pedestrian-vehicle size ratio and the impact speed are the two most influential factors that determine post crash pedestrian kinematics. The findings from the NASS-PCDS study were also confirmed and verified with the help of numerical simulations performed using two modified JAMA human FE models. An adult model (male, 175cm and 72kg) and a properly scaled child model (6 years old, 120cm and 24.5kg) were effectively utilized to investigate the post-crash kinematics in different conditions. The aim of this study is to investigate the main factors that determine post-crash pedestrian kinematics of 6-year (6YO) old child.

View full abstract

Show abstractHide abstract

The authors presented evaluation results of stress intensity factors and crack propagation rate in 3-dimensional mixed mode loading condition. In the mixed mode condition discontinuous crack surface is generated in some cases. The surface shape is called as factory roof, because its shape has discontinuous shape like a factory roof shape. The discontinuous surfaces sometimes contact each other. In such a complex phenomenon we and several researchers proposed an equation of equivalent stress intensity factor for mixed mode condition. In this study, we have precisely measured the discontinuous crack surface by cross sectional shape of the surface. An FE mesh is generated by using special treatment of node generation which is proposed by the authors. The proposed mesh generation techniques can guarantee no failure of mesh generation. We present evaluation results of stress intensity factors and crack propagation rate. The measurement shows that factory roof shape is very complex and a part of the section shows small fractured pieces. A FE mesh is just modeled according to typical configuration of the shape. The evaluation results show that the factors and the rate largely fluctuate, but its tendency of the rate is similar to the experiment.

View full abstract

Download PDF (511K)

Register with J-STAGE for free!