Preferential alignment of two-dimensional montmorillonite in polyolefin elastomer tube via rotation extrusion featuring biaxial stress field

2021 ◽  
Vol 215 ◽  
pp. 109034
Author(s):  
Changhua Yang ◽  
Qianyang Li ◽  
Min Nie ◽  
Qi Wang
Keyword(s):  
Stress Field ◽  
Biaxial Stress ◽  
Two Dimensional ◽  
Rotation Extrusion ◽  
Polyolefin Elastomer ◽  
Preferential Alignment

Modeling of a Beam and a Rotor with an Edge Crack Using Dissimilar Elements

2003 ◽  
Vol 9 (10) ◽  
pp. 1159-1187 ◽  
Author(s):  
A. Nandi ◽  
S. Neogy
Keyword(s):  
Finite Elements ◽  
Stress Field ◽  
Edge Crack ◽  
Three Dimensional ◽  
Transition Element ◽  
Two Dimensional ◽  
Cracked Beam ◽  
One Dimensional ◽  
Beam Elements ◽  
Dimensional Plane

Vibration-based diagnostic methods are used for the detection of the presence of cracks in beams and other structures. To simulate such a beam with an edge crack, it is necessary to model the beam using finite elements. Cracked beam finite elements, being one-dimensional, cannot model the stress field near the crack tip, which is not one-dimensional. The change in neutral axis is also not modeled properly by cracked beam elements. Modeling of such beams using two-dimensional plane elements is a better approximation. The best alternative would be to use three-dimensional solid finite elements. At a sufficient distance away from the crack, the stress field again becomes more or less one-dimensional. Therefore, two-dimensional plane elements or three-dimensional solid elements can be used near the crack and one-dimensional beam elements can be used away from the crack. This considerably reduces the required computational effort. In the present work, such a coupling of dissimilar elements is proposed and the required transition element is formulated. A guideline is proposed for selecting the proper dimensions of the transition element so that accurate results are obtained. Elastic deformation, natural frequency and dynamic response of beams are computed using dissimilar elements. The finite element analysis of cracked rotating shafts is complicated because of the fact that elastic deformations are superposed on the rigid-body motion (rotation about an axis). A combination of three-dimensional solid elements and beam elements in a rotating reference is proposed here to model such rotors.

Atomistic and Continuum Studies of Diffusional Creep and Associated Dislocation Mechanisms in thin Films on Substrates

2003 ◽  
Vol 779 ◽  
Author(s):  
Markus J. Buehler ◽  
Alexander Hartmaier ◽  
Huajian Gao
Keyword(s):  
Thin Films ◽  
Stress Field ◽  
Grain Boundary ◽  
Large Scale ◽  
Strain Relaxation ◽  
Dislocation Dynamics ◽  
Biaxial Stress ◽  
Diffusional Creep ◽  
Material Transport ◽  
Dynamics Simulations

AbstractMotivated by recent theoretical and experimental progress, large-scale atomistic simulations are performed to study plastic deformation in sub-micron thin films. The studies reveal that stresses are relaxed by material transport from the surface into the grain boundary. This leads to the formation of a novel defect identified as diffusion wedge. Eventually, a crack-like stress field develops because the tractions along the grain boundary relax, but the adhesion of the film to the substrate prohibits strain relaxation close to the interface. This causes nucleation of unexpected parallel glide dislocations at the grain boundary-substrate interface, for which no driving force exists in the overall biaxial stress field. The observation of parallel glide dislocations in molecular dynamics studies closes the theory-experiment-simulation linkage. In this study, we also compare the nucleation of dislocations from a diffusion wedge with nucleation from a crack. Further, we present preliminary results of modeling constrained diffusional creep using discrete dislocation dynamics simulations.

GROWTH HILLOCKS ON THE {100} FACES OF L-ARGININE PHOSPHATE MONOHYDRATE SINGLE CRYSTALS INVESTIGATED BY ATOMIC FORCE MICROSCOPY

2004 ◽  
Vol 11 (01) ◽  
pp. 71-75
Author(s):  
Y. L. GENG ◽  
D. XU ◽  
D. L. SUN ◽  
X. Q. WANG ◽  
G. H. ZHANG ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Stress Field ◽  
Single Crystals ◽  
Liquid Flow ◽  
Two Dimensional ◽  
Characteristic Structure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dislocation Sources ◽  
Extra Stress

Growth hillocks on the {100} faces of L-arginine phosphate monohydrate (LAP) single crystals grown at 25°C and at a supersaturation of 0.32 have been discussed. The typical dislocation growth hillocks are lopsided and elongate along the b direction. The dislocation sources are probably caused by the extra stress field which is introduced by the hollow cavities distributing on the steps and hillocks generated by the two-dimensional nucleus. The elongated shape is due to the characteristic structure of the LAP crystal. Apart from that, the formation of the lopsided growth hillocks is explained by the liquid flow theory.

Stress intensity factors in a biaxial stress field

AIAA Journal ◽  
1981 ◽  
Vol 19 (4) ◽  
pp. 537-538
Author(s):  
A. F. Liu
Keyword(s):  
Stress Intensity ◽  
Stress Field ◽  
Stress Intensity Factors ◽  
Biaxial Stress ◽  
Intensity Factors

Calculation of the effect of polymer additive in a converging flow

1987 ◽  
Vol 178 ◽  
pp. 423-440 ◽  
Author(s):  
G. Ryskin
Keyword(s):  
Stress Field ◽  
Channel Flow ◽  
Molecular Model ◽  
Two Dimensional ◽  
Polymer Additive ◽  
Polymer Molecules ◽  
Conical Channel ◽  
Proposed Model ◽  
Converging Flow ◽  
Good Agreement

The conical-channel flow of a dilute polymer solution is investigated theoretically. The stress field due to polymer additive is calculated using a new molecular model, based on the physical picture of the polymer molecules unravelling in strong flows and Batchelor's theory for the stress in a suspension of elongated particles. Good agreement is obtained with the experimental results of James & Saringer (1980). The absence of a significant polymer effect in a two-dimensional case (the wedge-channel flow), observed by the same authors (James & Saringer 1982a), is also explained. The fundamental differences between the proposed model and the elastic-dumbbell models are discussed.

Fatigue-crack propagation in a biaxial-stress field

1970 ◽  
Vol 10 (12) ◽  
pp. 529-533 ◽  
Author(s):  
S. R. Joshi ◽  
J. Shewchuk
Keyword(s):  
Fatigue Crack ◽  
Stress Field ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Biaxial Stress
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